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Light Trapping Plasmonic Butterfly Wing-Shaped Nanostructures for Enhanced Absorption and Efficiency in Organic Solar Cells

Kamal Kumar, Uttam Kumawat, Rohan Mital, and Anuj Dhawan

Doc ID: 338805 Received 10 Sep 2018; Accepted 15 Feb 2019; Posted 15 Feb 2019  View: PDF

Abstract: This paper presents organic solar cells (OSCs) containing a one-dimensional (1D) periodic array of plasmonic butterfly wing-shaped nanostructures, where silver butterfly wing-shaped nanostructures are present in the back-region of the active medium PTB7:PC71BM. Finite-difference time-domain (FDTD) modeling was employed to simulate the interaction of light with the plasmonic nanostructures, and it was demonstrated that these plasmonic nanostructures lead to a broadband-enhancement of light absorption in the active medium. These plasmonic nanostructures lead to enhanced scattering and trapping of the incident optical radiation at multiple wavelengths, due to surface plasmon excitation at these wavelengths. This enhanced scattering leads to an increased path-length of light as well as an enhanced intensity of the overall electric field in the active layer of the OSC, which further leads to an increase in absorption. The plasmonic butterfly wing-shaped nanostructures-containing solar cells were also simulated with indium tin oxide (ITO) nano-gratings placed on the top-surface of the solar cells. It was seen that the presence of the ITO nano-gratings leads to a further enhancement in absorption. In these organic solar cells containing both the plasmonic butterfly wing-shaped nanostructures and the ITO nano-gratings, the highest values of enhancements in the absorption and cell efficiency were calculated to be ~ 20 % and ~25 %, respectively.

Dark state atom mirrors based on artificial gauge fields

Vassilis Lembessis, Anwar Al Rsheed, Andreas Lyras, and Omar Aldossary

Doc ID: 349443 Received 31 Oct 2018; Accepted 14 Feb 2019; Posted 15 Feb 2019  View: PDF

Abstract: We propose the construction of an atom mirror for cold three-level atoms ina a dark state where the forces, responsible for the atomic reflection, are provided by artificial gauge fields. These fields are created from the total internal reflection of optical vortex beams with Gaussian intensity profiles at the interface of a dielectric prism and vacuum. We investigate the role of the photon angular momentum in the magnitude of these fields and consequently on the efficiency of atomic reflection.

Tunable magneto-optical linear and circular dichroism spectra for a dimer of core-shell prolate spheroids

Ebrahim Madadi, Atousa Khalilizadeh, and Mojtaba Nasiri

Doc ID: 352791 Received 26 Nov 2018; Accepted 14 Feb 2019; Posted 14 Feb 2019  View: PDF

Abstract: We study the magneto-optical properties of core-shell spheroidal nanoparticles.We apply the coupled dipole method to calculate the absorption, linear and circular dichroism spectra of a single and dimer of nanoparticles. The polarizability tensor of spherical nanoparticles is extended for spheroidal nanoparticles and by utilizing it, we show that the single spheroidalnanoparticle reveals circular dichroism. It is reported that core size and nanoparticles axis direction can be used to engineer the whole spectrum for both configurations.

Dissipative sensing with low detection limit in a self-interference micro-ring resonator

Hongliang Ren, Chang-Ling Zou, Jin Lu, Zichun Le, Yali Qin, Shuqin Guo, and Weisheng Hu

Doc ID: 354948 Received 10 Dec 2018; Accepted 14 Feb 2019; Posted 14 Feb 2019  View: PDF

Abstract: Abstract A dissipative sensing scheme based on a self-interference micro-ring resonator (SIMRR), which is robust against the lasing and micro-cavity frequency noise in the detecting system with a low noise level, is systematically investigated. The dependence of the performance of SIMRR sensor in both dispersive and dissipative sensing schemes on the physical structural parameters, e.g., the waveguide loss coefficient, the power coupling coefficient, the micro-ring radius and the initial sensing arm waveguide length in the SIMRR sensor, are studied. Based on the Cramer-Rao lower bound for parameter estimation, the detection limits of dispersive and dissipative sensing are theoretically and numerically analyzed, which demonstrate that the dissipative approach is immune from the frequency noises with a low noise level. The results show that the detection limit of dissipative sensing has great potential to achieve a better performance than that of dispersive sensing for a practical commercial tunable laser scanning system.

2D-FDTD Simulation of Ultra-compact Multifunctional Devices with Non-linear Photonic Crystal

ali farmani, ali mir, and maryam irannejad

Doc ID: 358170 Received 22 Jan 2019; Accepted 13 Feb 2019; Posted 14 Feb 2019  View: PDF

Abstract: In the present paper, we aim to report a ultra-compact AlGaAsk(3) photonic crystal structure to realize multifunctional logic responses. The properties of the proposed model are numerically investigated with different physical parameters by 2D-FDTD method. For this purpose, the effect of the geometrical parameters and dielectric material including Si and Insb, in near infrared region are studied. To obtain of dynamical tunability of the proposed model, the effect of defects are then utilized. Numerical resultsshow that the proposed devices are able to operate as multifunctional logic device. Moreover, the structure has a compact footprint of 8.85 mm × 8.85 mm × 100 nm. We expect that this theoretical result leads to remarkable applications in photonic integrated circuits, e.g. optical memory.

Ultrafast dynamic wavefront control for light redistribution via optical Kerr effect

Bin Zhang, Zheqiang Zhong, Zenghui Gao, and Zhan Sui

Doc ID: 345730 Received 12 Sep 2018; Accepted 13 Feb 2019; Posted 14 Feb 2019  View: PDF

Abstract: An approach for ultrafast dynamic light redistribution by wavefront control via the optical Kerr effect was proposed. In this approach, an intense pump laser with a temporal profile of a Gaussian pulse train was incident in a bulk Kerr medium to induce a spatiotemporal refractive index of the Kerr medium, and meanwhile a signal laser was propagating through the medium. Due to the spatiotemporal refractive index of the medium, the wavefront of the signal laser was modulated in both spatial and temporal domains. As a result, the Kerr medium functions as a moving microlens array for the pump beam perpendicular to the signal laser, and the Kerr medium functions as a varifocal lens for the pump beam oblique to the signal laser at a small angle. Consequently, the light field on the focal plane can be redistributed rapidly owing to the spatiotemporal wavefront modulation to the signal laser by the Kerr medium. Moreover, the response of the optical Kerr effect is on the order of sub-picosecond, which enables the light redistribution period of the signal laser to be below a few picoseconds. Results indicate that this approach can effectively shape the wavefront of the laser, then redistribute the light field on the focal plane and finally effectively improve the irradiation characteristics of the laser.

Electromagnetic surface waves guided by the planar interface of isotropic chiral materials

Maimoona Naheed, Muhammad Faryad, and Tom Mackay

Doc ID: 358011 Received 16 Jan 2019; Accepted 12 Feb 2019; Posted 13 Feb 2019  View: PDF

Abstract: The propagation of electromagnetic surface waves guided by the planar interface of two isotropic chiral materials, namely materials $\calA$ and $\calB$, was investigated by numerically solving the associated canonical boundary-value problem. Isotropic chiral material $\calB$ was modeled as a homogenized composite material, arising from the homogenization of an isotropic chiral component material and an isotropic achiral, nonmagnetic, component material characterized by the relative permittivity $\eps_a^\calB$. Changes in the nature of the surface waves were explored as the volume fraction $f_a^\calB$ of the achiral component material varied. Surface waves are supported only for certain ranges of $f_a^\calB$; within these ranges only one surface wave, characterized by its relative wavenumber $q$, is supported at each value of $f_a^\calB$.For $\mbox{Re} \lec \eps_a^\calB \ric > 0 $, as $\left| \mbox{Im} \lec \eps_a^\calB \ric \right|$ increases surface waves are supported for larger ranges of $f_a^\calB$ and $\left| \mbox{Im} \lec q \ric \right|$ for these surface waves increases. For $\mbox{Re} \lec \eps_a^\calB \ric < 0 $, as $ \mbox{Im} \lec \eps_a^\calB \ric $ increases the ranges of $f_a^\calB$ that support surface-wave propagation are almost unchanged but $ \mbox{Im} \lec q \ric $ for these surface waves decreases. The surface waves supported when $\mbox{Re} \lec \eps_a^\calB \ric < 0 $ may be regarded as akin to surface-plasmon-polariton waves, but those supported for when $\mbox{Re} \lec \eps_a^\calB \ric > 0 $ may not.

Magnetic-field controlled anomalous refraction in doped semiconductors

Edwin Moncada Villa, Juan Carlos Cuevas Rodríguez, and Antonio Fernández-Domínguez

Doc ID: 351740 Received 12 Nov 2018; Accepted 12 Feb 2019; Posted 12 Feb 2019  View: PDF

Abstract: We predict here that a slab made of a doped semiconductor can exhibit anomalous refraction under the applicationof a static magnetic field. This anomalous refraction takes place in the far-infrared range and it occurs for any angle ofincidence. We show that this effect is due to the fact that a doped semiconductor under a magnetic field can behave,to some extent, as a hyperbolic metamaterial. We also show that the occurrence of this anomalous refraction enables a semiconductor slab under a magnetic field to partially focus the electromagnetic radiation. The remarkable thing in our case is that we deal with naturally occurring materials and the anomalous refraction can be tuned at will with an external field.

Integrated Gbps quantum random number generator with real-time extraction based on homodyne detection

Leilei Huang and Hongyi Zhou

Doc ID: 346888 Received 26 Sep 2018; Accepted 11 Feb 2019; Posted 12 Feb 2019  View: PDF

Abstract: High-speed quantum random number generators are highly demanded in cryptographic systems, whose bottleneck lies in the ease of implementation and the efficiency of real-time post-processing. Based on homodyne detection of a coherent state, we realize a compact Gbps real-time quantum random number generator with a silica planar light circuit. We integrate all the modules onto a chip and simplify the balancing adjustment, which makes the system stable and robust. Real-time Toeplitz hashing extraction is implemented using a FPGA module with a final generation rate of 1 Gbps. Our demonstration shows an economic, compact, robust, and high-speed quantum random number generator available for commercialization.

Integrating machine learning techniques in quantum communication to characterise a quantum channel

Yaseera Ismail, Ilya Sinayskiy, and Francesco Petruccione

Doc ID: 348410 Received 17 Oct 2018; Accepted 11 Feb 2019; Posted 12 Feb 2019  View: PDF

Abstract: Free-space quantum communication technology has made significant advancements over the years. However to achieve a global quantum network there are still obstacles to overcome. To date, free-space quantum communication channels are faced with the challenges related to losses in the quantum channel, security and low data rates. Classical machine learning techniques provides a resourceful method for determining the properties of the free-space quantum channel. In this paper we used supervised machine learning to predict the atmospheric strength of a free-space quantum channel in the form the Strehl Ratio. We show that using the random forest regressor we could make predictions of the Strehl ratio of the quantum channel with a mean absolute percentage error of 4.44%. By adding the feature of the fidelity to the training set before and after the quantum channel we were able to predict the Strehl ratio with an improved mean absolute percentage error of 3.86%.

Effects of spectral filtering on pulse dynamics in carbon nanotube tunable mode-locked fiber laser

Zengrun Wen, Baole Lu, Xinyuan Qi, Chaoyang Zhang, Kaile Wang, Hao-wei Chen, and Jintao Bai

Doc ID: 349599 Received 01 Nov 2018; Accepted 11 Feb 2019; Posted 13 Feb 2019  View: PDF

Abstract: We investigate numerically the impact of spectral filtering on pulse characteristics in anomalous dispersion Erbium-doped fiber laser mode-locked with carbon nanotube based saturable absorber. The mode-locked fiber laser operates only in a single pulse state without filter; while it will transit to bound soliton states once the saturation energy of the gain fiber and the bandwidth of the filter are carefully chosen, respectively. Further analyzation shows that the filter in the cavity can provide the loss and frequency narrowing effects, which affect the laser performances, such as spectrum structure, pulse duration, pulse energy and peak power, both in frequency and time domains.

Hollow waveguide array with sub-wavelength dimensions as space-variant polarization converter

Stefan Belle, Stefan Helfert, Ralf Hellmann, and Jürgen Jahns

Doc ID: 355480 Received 18 Dec 2018; Accepted 08 Feb 2019; Posted 12 Feb 2019  View: PDF

Abstract: A hollow waveguide array with sub-wavelength dimensions is demonstrated as a polarization converter. An individual waveguide in the array has a rectangular cross-section, which leads to an anisotropy of propagation constants and therefore to a phase shift between vertical and horizontal field components upon propagation. The hollow waveguide array was fabricated by a two-photon polymerization process followed by electrochemical deposition of gold. The fabricated array consists of about 2000 x 2500 hollow waveguide cells, each with dimensions of 1150nm x 930nm and a height of 2µm. With these dimensions, the structure can, for example, be used at a wavelength of 1550nm. Other wavelengths and phase shifts are accessible by changing the dimensions of the cross-section and the height. Since the widths of individual waveguides are variable, space-variant operation can be implemented.

Improvement of optical image by measurement reduction technique at parametric multiplexing

Dmitriy Balakin and Anatoly Chirkin

Doc ID: 352935 Received 28 Nov 2018; Accepted 08 Feb 2019; Posted 08 Feb 2019  View: PDF

Abstract: In the process of parametric optical image amplification, images are formed at new frequencies in addition to the amplified original image. We show that the parametric multiplexing of optical images can be used to produce an image with improved quality. As an example, we study the parametric amplification of an optical image at low-frequency pumping in which multiplexed optical images turn out to be quantum-correlated. Additional improvement is made possible by using the information about the object that is available to the researcher, in particular, about sparsity of its image. To take the available information into account, we apply the measurement reduction technique.

A Nano-scale Planar Photodetector Based on Ring form MQWs For FIR Regime

Reza Mobini, MAhdi SOLEYMANI, and soosan Ghafar

Doc ID: 349384 Received 26 Oct 2018; Accepted 07 Feb 2019; Posted 08 Feb 2019  View: PDF

Abstract: In This paper, we proposed a new design for infrared photodetector structure based on ring shape MQWs for LIR and FIR regimes. The absorption coefficient of proposed photodetector that consists of GaAs/Al0.25Ga0.75As QWs with thickness of 4 nm and barrier of 40 nm, has calculated, which a dominant peak at 52 has um located in FIR regime. The proposed device has planar structure with low thickness comparing ordinary rectangular MQW photodetector. Also there is 100% enhancement in typical IR absorption vs these ordinary photodetector. Electronic states and wave functions calculated through solving Schrodinger equation and the effect of QW number in important parameters of photodetector like gain mode and dark current have been investigated. According the results, dark current one order of magnitude decreases with increasing number of QWs from 3 to 4. Also absorption has red shift and increases simultaneously.

Infrared photoreflectance of InSb-based two-dimensional nanostructures

Dmitrii Firsov, Oleg Komkov, Victor Solov'ev, Alexei Semenov, and Sergey Ivanov

Doc ID: 356106 Received 21 Dec 2018; Accepted 07 Feb 2019; Posted 08 Feb 2019  View: PDF

Abstract: Infrared photoreflectance (PR) study of two-dimensional nanoheterostructures based on InSb was performed for the first time by using FTIR photomodulation spectroscopy. The studied structures, including InSb/AlxIn1-xSb quantum wells (QWs), and type-II nanostructures with monolayer-thick InSb insertions within bulk InAs layers, were grown by molecular beam epitaxy on GaAs (001) and InAs (001) substrates, respectively. The PR spectra of InSb/AlxIn1 xSb heterostructures exhibited a series of signals from the QWs, including the spin-orbit split band, as well as the AlxIn1-xSb layers, which enabled control of the barrier height and composition. A comparison of the experimental results with calculations made by the effective mass approximation technique was used to identify several optical transitions observed within the QWs, including those related to the excited states not visible in the photoluminescence spectra. For the InSb/InAs monolayer nanostructures, an analysis of the PR spectra features allowed for determination of their energy spectrum, internal electric field value, and localization energy of holes up to room temperature.

HSD-Correlation beyond entanglement in InAs Nanowire System With Spin-OrbitInteraction and External Electric Field

Abdel-Baset Mohamed, Ali Homid, Mahmmoud Aty, and Hichem Eleuch

Doc ID: 354989 Received 13 Dec 2018; Accepted 06 Feb 2019; Posted 08 Feb 2019  View: PDF

Abstract: A new analytical description is obtained for a ballistic quantum wire under Rashba spin-orbit mechanism with a magnetic field. The system is also analyzed for two different cases with and without an external electric field. Hilbert-Schmidt distance (HSD) and concurrence are employed towitness quantum correlation (QCs) of the electron-harmonic system beyond quantum entanglement (QE). The robustness and stability of the initial maximal correlation are explored. It is shown that the generation and enhancement of quantum correlations can be controlled for particular external electric fields. Furthermore, this study is shown that the HSD-correlation is always present independently of the existence of the magnetic field and the external electric field. The external electric field reduces the effect of the interaction of the electron-harmonic system, therefore it leads to the conservation of the initial quantum correlations.

Photoluminescence decay rate of an emitter layer on an Al nanocylinder array: Effect of layer thickness

Yuki Kawachiya, Shunsuke Murai, Motoharu Saito, Koji Fujita, and Katsuhisa Tanaka

Doc ID: 357464 Received 11 Jan 2019; Accepted 06 Feb 2019; Posted 06 Feb 2019  View: PDF

Abstract: Photoluminescence (PL) of emitters on periodic arrays of plasmonic nanocylinders can be modulated largely by the interaction of the emitter with the plasmonic modes excited on the array. An energy transfer to metal, or non-resonant coupling of the emitters to high-order dark plasmonic modes, works as a nonradiative decay path to decrease the PL intensity. In this study, via PL decay rate measurements, we systematically investigated how the thickness of emitter layer affected the energy transfer. An Eu complex was selected as an emitter, where Eu3+ acts as a light-emitting center with a high quantum yield. Thin layers of Eu complex showed an absorption coefficient of 3.4 × 104 cm-1, corresponding to the absorption length of 290 nm at a wavelength of 325 nm, i.e., the excitation wavelength used in this study. The thickness critically affected the energy transfer ratio, which was reduced as the thickness of the layers increased, and was almost suppressed when the thickness was 1000 nm. The results suggest there is an optimal thickness where PL enhancement is obtained with suppression of energy transfer.

Bi-transmitter coherent-state quantum key distribution

Stephen Barnett, Thomas Brougham, Sarah Croke, and Simon Phoenix

Doc ID: 347077 Received 01 Oct 2018; Accepted 06 Feb 2019; Posted 08 Feb 2019  View: PDF

Abstract: We propose a scheme for quantum key distribution in which the two communicatingparties, Alice and Bob, each send a weak coherent pulse to a third party stationedbetween them. The key bits are generated by interference between these pulses,with the results communicated to Alice and Bob. Optimized strategies for eavesdropping on the communication are built upon state discrimination and quantum non-demolition measurements.

Stored Electromagnetic Field Energies in General Materials

Geyi Wen

Doc ID: 351503 Received 08 Nov 2018; Accepted 05 Feb 2019; Posted 06 Feb 2019  View: PDF

Abstract: The most general expressions for the stored field energies in frequency domain, which are independent of any constitutive relations and microscopic models, are derived from the time-domain Poynting theorem by using complex frequency-domain approach. When the complex frequency-domain approach is applied to Maxwell equations, two energy conservation laws are obtained simultaneously. The first is the well-known Poynting theorem, while the second is new in its general form and contains the newly derived expressions for the stored field energies. In contrast to the well-established Poynting theorem in frequency domain, the real part of the second energy conservation law gives an equation for the sum of stored electric and magnetic field energies; the imaginary part involves an equation related to the difference between the dissipated electric and magnetic field energies. When media are lossless, the new expressions for the stored field energies are shown to agree with all the previous studies; when media are lossy, they include new terms that were not shown in previous reports. These additional terms represent the dispersive part of the stored energies and reflect the influences of the losses on the stored energies.

Transit Ramsey EIT resonances in a Rb vacuum cell

Irina Novikova, Eugeniy Mikhailov, and Ravn Jenkins

Doc ID: 354411 Received 04 Dec 2018; Accepted 01 Feb 2019; Posted 04 Feb 2019  View: PDF

Abstract: We report the observation of a transient spectral feature in a dual-channelarrangement for electromagnetically-induced transparency in a vacuum Rbvapor cell, caused by the consecutive interaction of the atoms traversingboth laser beams while preserving their ground-state spin coherence.Despite a relatively small fraction of atoms participating in this process,their contribution to the overall lineshape is not negligible, and can becontrolled by the adjustment of the relative phases between the opticalfields in the two interaction regions. We also demonstrate that, thanks to the extended spin coherence evolution time, such differential intensity measurements can produce an error signal for the microwave frequency stabilization as strong as single-channel measurements.Additionally, the effective cancellation of the intensity noise, dominatingthe single channel detection, results in more than an order of magnitude higher signal-to-noise ratio.

Pure even and odd harmonics produced in modelled hydrogen molecular ions in single-color strong laser fields

Feng He and Liang Xu

Doc ID: 352850 Received 26 Nov 2018; Accepted 31 Jan 2019; Posted 01 Feb 2019  View: PDF

Abstract: The even and odd high-order harmonic generation in a modeled hydrogen molecular ion in strong laser fields is studied by numerically simulating the time-dependent Schrödinger equation. By applying a linearly polarized laser pulse whose polarization axis is perpendicular to the molecular axis, the pure odd harmonics polarized along the laser polarization direction are produced. Meanwhile, the pure even harmonics polarized along the molecular axis may be produced simultaneously either by adding an extra weak direct-current electric field along the molecular axis, or by artificially setting asymmetric charges for the two nuclei. The Bohmian trajectories reveal that the pure even harmonics are contributed by the dipole formedby the asymmetric expansion of the ionized wave packet along the molecular axis, instead of the asymmetric Coulomb attraction for the rescattering electron as expected. Moreover, the relationship between the symmetry of molecular orbital and the parity of high-order harmonics is also explored.

Remote implementation of single-qubit operations via hyperentangled states with cross-Kerr nonlinearity

Xian-Fang Jiao, Ping Zhou, and Shu-Xin Lv

Doc ID: 355278 Received 13 Dec 2018; Accepted 30 Jan 2019; Posted 01 Feb 2019  View: PDF

Abstract: Quantum information processing via hyperentanglement can improve the quantum channel capacity for long-distance quantum communication and large-scale quantum communication network. Some important works have been presented in quantum remote state preparation with hyperentangled states. However, the protocols for quantum operation remote implementation are based on quantum systems encoded in one degree of freedom. We present a quantum operation remote implementation protocol for arbitrary single-qubit operations with two-photon hyperentangled states via cross-Kerr nonlinearities. Moreover we discuss the scheme for parallel remote implementation of partially unknown quantum operations via two-photon hyperentangled states.

Modeling and optimization of transverse modes in Vertical External Cavity Surface Emitting Laser

Alexandre Laurain, Jorg Hader, and Jerome Moloney

Doc ID: 357560 Received 14 Jan 2019; Accepted 30 Jan 2019; Posted 01 Feb 2019  View: PDF

Abstract: We present a system-oriented model to simulate the dynamics of transverse modes in Vertical External Cavity Surface Emitting Lasers (VECSEL). An analytical expression for the gain as a function of carrier density and temperature is derived from a simulation of the full structure reflectivity, while the field propagation in the cavity is computed with a generalized Huygens-Fresnel integral. The laser rate equations are employed to calculate the field and gain dynamics until a steady state is reached. The optimal cavity mode size for highest output power and brightness is extracted for two of the most commonly employed pump beam shapes. The effect of pump power and output coupler on the steady state solution and mode size optimum are discussed.

Necessary conditions for out-of-plane lattice plasmons in nanoparticle arrays

Gordon Li and Guangyuan Li

Doc ID: 354608 Received 04 Dec 2018; Accepted 29 Jan 2019; Posted 01 Feb 2019  View: PDF

Abstract: Out-of-plane lattice plasmons (OLPs) supported by metallic nanoparticle arrays are promising in diverse applications due to their remarkably narrow linewidths and significant enhancement of local fields. Here we investigate the necessary conditions for metallic nanoparticle arrays to achieve OLPs. Our results show that, besides the prerequisites of large height, oblique incidence, and TM polarization, which have been pointed out by the literature, the array period should be properly designed within a limited range, the dielectric environment should be homogeneous, and the height and the angle of incidence need to be optimized. We expect this work will advance the understanding and engineering of OLPs in metallic nanoparticle arrays and promote their applications in nanolasers, SERS, ultrasensitive biochemical sensors, and nonlinear optics.

Band structure of two-dimensional photonic crystals that include dispersive left-handed materials with rough surfaces in their lattice

Victor Castillo-Gallardo, Luis Puente Díaz, Hector Perez Aguilar, Alberto Mendoza Suárez, and Francisco Villa

Doc ID: 341568 Received 06 Aug 2018; Accepted 29 Jan 2019; Posted 29 Jan 2019  View: PDF

Abstract: In present work, we calculate the photonic band structure in 2D photoniccrystals composed of a dielectric and a dispersive metamaterial withcylindrical inclusions that present rough surfaces by using an integral method. We find that for purely dielectric photonic crystals with a relatively small roughness (compared to the wavelength), the band structures remain unperturbedcompared to those associated to photonic crystals with smooth surfaces. However, when a dispersive left-handed material is included in the lattice, the band structures become strongly affected especially under TM polarization, since new photonic band gaps arise. Moreover, the band gaps present with smooth surfaces, change their position becoming narrower or generating more band gaps in the same region.

Generating Lieb and super-honeycomb lattices by employing the fractional Talbot effect

Hua Zhong, Yiqi Zhang, Milivoj Belic, and Yanpeng Zhang

Doc ID: 349360 Received 26 Oct 2018; Accepted 29 Jan 2019; Posted 12 Feb 2019  View: PDF

Abstract: We demonstrate a novel method for producing optically-induced Lieb and super-honeycomb lattices, by employing the fractional Talbot effect of specific periodic beam structures. Our numerical and analytical results display the generation of Lieb and super-honeycomb lattices at fractional Talbot lengths effectively and with high beam quality. By adjusting the initial phase shifts of the interfering beams, the incident periodic beam structures, as well as the lattices with broken inversion symmetry, can be constructed in situ. A simple experimental 4f-system with two convex lenses and a phase mask can be implemented to construct such lattices. This research suggests not only a possible practical utilization of Talbot effect in the production of novel optically-induced lattices but also in the studies of related optical topological phenomena.

Atomic quadrature squeezing and quantum state transfer in a hybrid atom-optomechanical cavity with two Duffing mechanical oscillators

M. H. Naderi and Farzaneh Momeni

Doc ID: 351169 Received 05 Nov 2018; Accepted 28 Jan 2019; Posted 29 Jan 2019  View: PDF

Abstract: In this paper, we investigate theoretically the quantum state transfer in a laser driven hybrid optomechanical cavity with two Duffing-like anharmonic movable end mirrors containing an ensemble of identical two-level trapped atoms. The quantum state transfer from the Bogoliubov modes of the two anharmonic oscillators to the atomic mode results in the atomic quadrature squeezing beyond the standard quantum limit of 3 dB which can be controlled by both the optomechanical and atom-field coupling strengths. Interestingly, the generated atomic squeezing can be made robust against the noise sources by means of the Duffing anharmonicity. Moreover, the results reveal that the presence of the Duffing anharmonicity provides the possibility of transferring strongly squeezed states between the two mechanical oscillators in a short operating time and with a high fidelity.

Hysteresis in the spontaneous emission induced by $VO_2$ phase-change

Daniela Szilard, W. Kort-Kamp, F Rosa, F Pinheiro, and C Farina

Doc ID: 349909 Received 05 Nov 2018; Accepted 27 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: We investigate the spontaneous emission of a two-level quantum emitter in the vicinity of a vanadium dioxide ($VO_2$) thin film. By taking advantage of effective medium techniques to describe the dielectric constant of the $VO_2$ we demonstrate that, in the near-field regime, the spontaneous emission rate of both electric and magnetic dipole emitters can be maximized at the insulator-to-metal phase transition temperature of the film. We find that $VO_2$'s thermal hysteresis curve produces clear fingerprints in the emitter's decay process, offering a new degree of freedom to dynamically control light emission at the nanoscale. We also find that the spontaneous emission rate is a non-monotonic function of the emitter transition wavelength, presenting a pronounced peak at infrared frequencies. Altogether, our results reveal that $VO_2$ phase-transition is a promising mechanism to achieve on-demand tuning of an emitter's lifetime.

Design of aluminum-based nanoring arrays for realizing efficient plasmonic sensors

Mehrnoosh Salemizadeh, Fatemeh Fouladi Mahani, and Arash Mokhtari

Doc ID: 351112 Received 05 Nov 2018; Accepted 27 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: In this work, for the first time, an aluminum-based plasmonic nanoring array has been employed to present a practical approach for design of efficient optical sensors. Applying aluminum for this design benefits from cost-effectiveness, CMOS-compatibility, and ease of fabrication while offering tunable and selective optical characteristics. Utilizing surface plasmon resonances of the proposed nanostructure, an effective refractive index sensor at visible wavelengths has been achieved. The simulation results show a high sensitivity up to 408 nm/RIU with a figure of merit of 5.88 which is comparable to those of gold-based plasmonic sensors and even outperforms some of them.

Quadratic detection of an enhanced self-mixing laser Doppler signal with two-photon absorption

Jun Chen, hao lin, Wei Xia, Hui Hao, Dongmei Guo, and Ming Wang

Doc ID: 352398 Received 20 Nov 2018; Accepted 27 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: A new detection scheme is proposed for the enhanced self-mixing laser Doppler velocimeter (SLDV) using two-photon absorption (TPA), which is based on the TPA-induced quadratic photoconductivity dependence of a photodiode on the incident radiance at 1550nm with self-mixing interference (SMI). The harmonics of the SMI signal in the frequency spectrum are enhanced simultaneously as for an FBG-based enhanced SLDV. The quadratic response induced by TPA can suppress the undesirable harmonics, making their amplitude into the same level as the noise. From the experimental results presented in this letter, TPA effect in a commercial Si photodiode implements a sort of ultra-wide bandwidth filter without passively adjusting the cut-off frequencies for an unknown Doppler frequency, which simplifies the Doppler signal processing. The SNR is also improved to a considerable level of 15dB for a Doppler frequency of 4 kHz due to the amplification of an EDFA. This Letter provides guidance for the design of the enhanced SLDV with the optical filtration.

Influence of Raman scattering on quantum noise in dual-pumped phase-sensitive amplification in an optical fiber

Kyo Inoue

Doc ID: 346733 Received 25 Sep 2018; Accepted 26 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: Phase-sensitive amplification (PSA) can provide low-noise signal amplification, and a quantum-limited noise figure of 0 dB, i.e., additional noise free amplification, is achievable theoretically. However, in fiber-based single-pumped PSA systems, it has been reported that Raman scattering in the fiber degrades the noise figure from the ideal 0 dB. In the present study, the influence of Raman scattering on quantum noise in fiber-based dual-pumped PSA is investigated. A quantum mechanical treatment starting from the Heisenberg equation of motion is developed, considering the parametric interaction and Raman interaction simultaneously, and an analytical expression for the noise figure is derived. An example of calculation is also presented, which quantitatively indicates the degradation in the noise figure due to Raman scattering.

Wide-range and self-locking atomic magnetometer based on free spin precession

Pei-Xian Miao, Wenqiang Zheng, Shi-Yu Yang, Bin Wu, Bing Cheng, Jianhui Tu, Hong-Liang Ke, Wei Yang, Ji Wang, Jingzhong Cui, and Qiang Lin

Doc ID: 347282 Received 04 Oct 2018; Accepted 26 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: The magnetic field is one of the most fundamental and ubiquitous physical observables, often conveying rich information about its generation source. Atomic magnetometers have been proven to be a high-potential technique for weak magnetic field measurement with various applications. However, due to the lack of excellent frequency-locking ability to abrupt magnetic field changes, atomic magnetometers are limited to use in the application scenarios, which require both of wide-range and self-locking characteristics. In this paper, theoretical and experimental researches for a wide-range and self-locking rubidium atomic magnetometer based on free spin procession are presented. The rubidium atomic magnetometer can track magnetic field jump of 10000 nT in the measurement range from 500 nT to 100500 nT. Atomic magnetometer with excellent self-locking ability in wide range would develop into new highly sensitive magnetic measuring devices, enabling geomagnetic measurement in real environment and monitoring the magnetic phase transitions or coercive fields of soft magnetic materials.

Exploration of Micro-VCSEL Ultra-low Biasing Scheme for Pulse Generation

Tao Wang, Gaofeng Wang, GianPiero Puccioni, and Gian Luca Lippi

Doc ID: 348515 Received 17 Oct 2018; Accepted 26 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: The generation of optical pulses at ultralow bias level, thus low energy cost, is explored in a commercial microcavity semiconductor laser in view of testing the principle of energy efficientinformation encoding in potential integrated schemes. Sequences of regular, highly nonlinear pulses with acceptable amplitude stability are obtained from a commercial device as potential sources ofbits where the information is added by post-treatment (pulse removal). A discussion on the energy expenditure per bit is offered, together with the optimal frequency for pulse generation, which isfound to lie slightly below the above-threshold value declared by the manufacturer.

Terahertz focusing properties of polymeric zone plates characterized by a modified knife-edge technique

Silvia Tofani, Dimitrios Zografopoulos, Mauro Missori, Renato Fastampa, and Romeo Beccherelli

Doc ID: 353319 Received 04 Dec 2018; Accepted 26 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: The focusing properties of a series of polymeric zone-plate lenses are investigated around the target frequency of 1 THz. Their characterization is performed by means of THz time-domain spectroscopy, employing a modified knife-edge technique that compensates for asymmetries of the impinging THz beam shape of typical photoconductive antenna-based THz sources. The samples are fabricated by a three-axis milling technique on slabs of an ultralow-loss cyclo-olefin polymer. Three different zone plates are studied, a conventional binary zone plate, a conventional four-level zone plate and a recently introduced double-sided zone plate consisting of the stack of two phase-reversal binary zone plate, which is simpler to fabricate and less sensitive to mechanical damage than multilevel zone plates. Experimental results, coupled with finite-element simulations, demonstrate that the double-sided zone plate features a resolution increased by about 3λ with respect to the binary zone plate and comparable with that of the four-level zone plate. The double-sided zone plate has 40% lower focusing efficiency and approximately 7λ shorter depth of field compared to its four-level counterpart. Nevertheless, it outperforms conventional binary zone plates by 25% in power focusing efficiency and features 10λ longer depth of field.

Metasurface based patterned waveplates for VIS applications

Carsten Stock, Thomas Siefke, and Uwe Zeitner

Doc ID: 355470 Received 18 Dec 2018; Accepted 26 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: We present the design and fabrication of metasurface type patterned waveplates for VIS applications. The metasurface consists of a grating structure with periods much smaller than the addressed wavelength. By using character projection e-beam lithography (CP-EBL) for the fabrication, various shapes, orientations, sizes and patterns can be realized within affordable exposure times. For the first demonstration, a pattern with different orientations of the grating ridges of quarter-waveplates for 532 nm wavelength is presented.

Single-step creation of polarization gratings by scanning wave photopolymerization with unpolarized light

Kyohei Hisano, Megumi Ota, Miho Aizawa, Norihisa Akamatsu, Christopher Barrett, and Atsushi Shishido

Doc ID: 355502 Received 17 Dec 2018; Accepted 26 Jan 2019; Posted 01 Feb 2019  View: PDF

Abstract: Liquid crystalline materials with a cycloidal molecular orientation pattern are attractive for fabricating diffractive waveplates, diffracting incident light regardless of its polarization state into left and/or right circularly polarized light only in +1st and/or –1st orders, applicable as next-generation optical devices. However, large-area high-speed processing of such molecular orientation is a challenge since even state-of-the-art photoalignment methods require a precise spatial modulation of the polarization states of incident light, e.g. polarization holograms. Here, we propose and demonstrate that unpolarized light could generate cycloidal molecular orientation patterns over large-areas easily in a single step merely by using our recently-developed method of “scanning wave photopolymerization” with a simple optical setup. Importantly, the processing time for fabricating millimeter-scale films was significantly decreased to less than a few minutes. Detailed investigation revealed that the resultant film showed the desired diffraction behavior with a diffraction efficiency of 50%.

Pancharatnam-Berry Optical Lenses

Hao Yu, Ziyuan Zhou, YongLe Qi, Xinfang Zhang, and Qihuo Wei

Doc ID: 356984 Received 07 Jan 2019; Accepted 26 Jan 2019; Posted 01 Feb 2019  View: PDF

Abstract: In this paper, we clarify a few aspects of Pancharatnam-Berry (PB) phase optical lenses. Firstly, we provide theoretical formulae on how the optical efficiency, focal length and point spread functions depend on wavelength and validify them with numerical calculations based on Fresnel diffraction theory. Secondly, we perform numerical studies on how optical efficiency are affected by discretization of the PB phase. We find that phase discretization significantly lowers the optical efficiency for low f-number PB lenses.

Static and dynamic mode instabilities in dual-core fiber amplifiers

Jesper Laegsgaard, Federica Poli, Annamaria Cucinotta, and Stefano Selleri

Doc ID: 354884 Received 11 Dec 2018; Accepted 25 Jan 2019; Posted 25 Jan 2019  View: PDF

Abstract: This paper provides a detailed derivation of coupled-mode equations for thermo-optic nonlinear effects in dual-core fiber amplifiers. The equations predict both static and dynamic modal deformations depending on amplifier design. The prediction of static deformations is confirmed by nonlinear beam-propagation simulations. The dependencies of instabilities and their thresholds on launch conditions are analyzed by numerical simulations and analytical arguments. It is shown that the output stability properties are strongly dependent on the relative phase of the input in the two cores. The instability power threshold for dual-core amplifiers with strongly coupled cores are found to be lower than for a comparable single-core amplifier. However, as the core separation is increased, the dual-core amplifier threshold rapidly increases when light is amplified in the odd supermode.

Applications of frequency locking effect in acousto-optic systems for the optical radiation spectral composition control

Sergey Mantsevich and Vladimir Balakshy

Doc ID: 347353 Received 02 Oct 2018; Accepted 24 Jan 2019; Posted 25 Jan 2019  View: PDF

Abstract: The spectral optoelectronic system combining collinear acousto-optic cell and positive electronic feedback is examined. The operation of this system in the generation mode and the possibilities of system self-oscillations locking effect practical application for controlling the semiconductor lasers optical radiation mode composition are studied. The design and the test results of the new acousto-optic (AO) device that can be treated as time-domain optical demultiplexer are described. This demultiplexer applies frequency locking effect also. The presented demultiplexer model obtain the following characteristics: wavelength spacing between channels is less than 0.6 nm, the channel passband width is 0.4 nm, the crosstalk attenuation between adjacent channels is more than 42 dB, the insertion loss is less than 2 dB and the demultiplexer optical tuning range corresponds to the AO filter tuning range that is not less than one octave.

Mode characteristics analysis of fiber Bragg gratings in large-mode-area double-clad fibers

Di Wang, qinggui tan, xiaojun li, Ge Jinman, wei jiang, Dong Liang, and Haiwen Cai

Doc ID: 354530 Received 04 Dec 2018; Accepted 24 Jan 2019; Posted 25 Jan 2019  View: PDF

Abstract: Fiber Bragg gratings in large-mode-area double-clad fibers (LMA-DCFBGs) are the key components for high power all-fiber lasers. The mode characteristics analysis of LMA-DCFBG is of great significant for mode selection and performance optimization for high power fiber lasers. In this paper, the spectra characteristics of LMA-DCFBG were studied theoretically and experimentally, which confirmed that there is the power conversion between LP01 mode and LP11 mode in LMA-DCFBG. Then the growth curves of coupling coefficients of LMA-DCFBG with increasing irradiation dose of ultraviolet (UV) light were measured. The results demonstrated that coupling efficiency between LP01 mode and LP11 mode is independent of the polarization state of UV lasers. In high power fiber lasers, according to the spectra characteristics of LMA-DCFBGs, it can be considered that mode selection of fiber lasers could be realized by a pair of FBGs inscribed in fibers with different structural parameters, and that the appropriate wavelength matching condition could effectively avoid the laser power conversion from LP01 mode to LP11 mode, which could improve the beam quality of the output laser

Quantum description of a PT-symmetric nonlinear directional coupler

Vlasta Perinova, Antonin Luks, and jaromir krepelka

Doc ID: 352516 Received 20 Nov 2018; Accepted 23 Jan 2019; Posted 29 Jan 2019  View: PDF

Abstract: The dielectric media with balanced gain and loss are called PT-symmetric also by the analogy between the description of light propagation in these media by the paraxial Helmholtz equation and the description of time evolution of a particle's wavefunction by the Schrödinger equation with a PT-symmetric Hamiltonian. This analogy is complicated by considering the nonlinearity of the medium. In this connection, we speak of the PT-symmetric nonlinear directional couplers. First, we replace the classical description of propagation with a quantum description, whose Hamiltonian is also PT-symmetric in a suitable sense. We point out that the quantum characteristics which are usually determined cannot be reduced to observables of the PT-symmetric quantum theory. We then adopt the standard quantum description of a coupler with gain and loss. Through numerical calculation we find that, for lower gain rates, the oscillatory behavior of the coupler changes only a little under the influence of the supplied noise. But for higher gain rates, the noise causes that the coupler behaves like above the threshold of the increase of the photon number in one mode. In the coupler without the cross-Kerr interaction, this behavior is more pronounced. In this connection, the first- and second-order correlation functions exhibit a temporary oscillatory behavior for higher gain rates.

Casimir-Polder forces in inhomogeneous backgrounds

Kimball Milton

Doc ID: 349867 Received 01 Nov 2018; Accepted 23 Jan 2019; Posted 25 Jan 2019  View: PDF

Abstract: Casimir-Polder interactions are considered in an inhomogeneous, dispersive background. We consider both the interaction between a polarizable atom and a perfectly conducting wall, and between such an atom and a plane interface between two different inhomogeneous dielectric media. Renormalization is achieved by subtracting the interaction with the local inhomogenous medium by itself. The results are expressed in general form, and generalize the Dzyaloshinskii-Lifshitz-Pitaevskii interaction between a spatially homogeneous dielectric interface and a polarizable atom.

High-precision three-dimensional atom localizationvia Kerr nonlinearity

yin hong, Zhiping Wang, and Yu Benli

Doc ID: 346747 Received 25 Sep 2018; Accepted 23 Jan 2019; Posted 25 Jan 2019  View: PDF

Abstract: Recently, there are many schemes for achieving high-dimensional atom localization viameasuring the first-order linear susceptibility. Here, we present a new scheme for high-precisionthree-dimensional (3D) atom localization in a three-level atomic system based on the Kerrnonlinearity, which refers to the real part of the third-order nonlinear susceptibility. Due to thespace-dependent atom-field interaction, the position information of the atom can be determined bymeasuring Kerr nonlinearity in 3D space. Interesting, by properly varying the parameters of thesystem, we find that there is only a small sphere in 3D space, which means the probability offinding the atom at a particular position can be 100%. Our scheme not only shows a new way toachieve high-precision and high-efficiency 3D atom localization, but also provides some potentialapplications in high-dimensional atom nanolithography.

Tuning of longitudinal plasmonic coupling in graphene nanoribbon arrays / sheet hybrid structures at midinfrared frequencies

Jigang Hu, Xiaohang Wu, Hong-Ju Li, Enxu Yao, weiqiang xie, Wei Liu, Yonghua Lu, and Changjun Min

Doc ID: 345800 Received 01 Oct 2018; Accepted 21 Jan 2019; Posted 24 Jan 2019  View: PDF

Abstract: Coupling and hybridization of the plasmon polaritons can commonly occur in graphene plasmonic nanostructures, providing new possibilities for developing many novel plasmonic optoelectronic devices. Here we have theoretically investigated the longitudinal plasmonic coupling between the localized and the delocalized surface plasmon polaritons in a graphene nanoribbon arrays and monolayer composite structure at mid-infrared region. It has been demonstrated that vertical plasmonic coupling can be actively controlled by either the geometric parameters or the Fermi energy in graphene, allowing for the strong light-matter interaction. Thanks to the strong plasmon coupling, a dual-band perfect absorption with A≈100% and a large Rabi splitting exceeding 17.2 meV have been observed in absorption spectra of this hybrid system. More intriguingly, we found, by varying the distance between graphene sheet and metallic substrate, periodic spectral nodes can emerge in absorption response of the hybrid mode, which was explained by mechanism of longitudinal microcavity resonance in this coupled system. The controllable plasmonic coupling and ultrahigh dual-band absorption capability offered by this hybrid coupled structure opens new avenues for designing the tunable multi-channel graphene optoelectronic devices with high performance.

Q-plate technology: a progress review

Andrea Rubano, Filippo Cardano, Bruno Piccirillo, and Lorenzo Marrucci

Doc ID: 356888 Received 04 Jan 2019; Accepted 21 Jan 2019; Posted 25 Jan 2019  View: PDF

Abstract: Since their first introduction, in 2006, q-plates have found a constantly increasing number of uses in diverse contexts, ranging from fundamental research on complex structured light fields to more applicative innovations of established experimental techniques, passing through a variety of other emerging topics, such as, for instance, quantum information protocols based on the angular momentum of light. In this manuscript we present a bird's-eye view of the progress of this technology in recent years, and offer some educated guesses on the most likely future developments.

Polarization effects in optical microresonators

Mohd Narizee Mohd Nas, Shahab Bakhtiari Gorajoobi, Ganapathy Senthil Murugan, and Michalis Zervas

Doc ID: 349363 Received 26 Oct 2018; Accepted 20 Jan 2019; Posted 24 Jan 2019  View: PDF

Abstract: Polarization effects in different types of optical microresonators namely, a microsphere, a cylindrical microresonator (MR), a milled MR and a microbottle resonator (MBR), are studied in detail. A polarimetric set-up was utilized to investigate the evolution of the transmission dips, polarization cross-coupling (PXC) peaks and scattered light as the input polarization is varied. It is shown that the transmission dip and PXC minima are shifted with respect to the ideally expected input polarization angle. A theoretical model based on Jones matrix calculus was developed in order to identify the root cause of the observed effects. The modelling has attributed the observed shifts to the residual birefringence of the output part of the micro-taper fiber, used for evanescent coupling into the MRs.

Numerical Simulation of Ultrashort Laser Pulse Amplification

Ramon Springer, Johannes Heberle, Ilya Alexeev, and Christoph Pflaum

Doc ID: 349627 Received 01 Nov 2018; Accepted 19 Jan 2019; Posted 24 Jan 2019  View: PDF

Abstract: Within this work, the numerical solution of the photon transport equation forpulse amplification is presented. Several discretization schemes are introduced that enable the calculation of the coupling between the transport equation and population inversion. It is demonstrated that the presented discretization schemes are convergent with respect to the analytic Frantz-Nodvik solution. Specifically, the application of a prediction-correction approach based on Heun’s method leads to a significant improvement in accuracy compared to the pure explicit approach. Finally, the novel discretization schemes were applied to simulate a Ti:Sapphireregenerative amplifier. The well agreement of simulated results with experimental measurements qualifies the presented discretization schemes to simulate ultrashort pulse amplification.

Effect of the thermally excited lower laser level in a neodymium-doped fiber

Jean-Francois Bisson, Mitsuhiro Iyoda, Yuta Yasumatsu, Masamori Endo, and Taizo Masuda

Doc ID: 351677 Received 12 Nov 2018; Accepted 19 Jan 2019; Posted 24 Jan 2019  View: PDF

Abstract: The neodymium-doped optical fiber operated at 1.1 μm is a very promising material for the solar-pumped laser without concentrator because of its strong absorption bands in the visible region and its extremely low optical losses. It is generally considered a true four-level system owing to the large energy gap of the lower level of the laser transition to the ground level. In this study, the exquisitely small thermally excited population in the 4I11/2 Stark level is shown to be primarily responsible for the absorption losses at the laser wavelength at room temperature. Thanks to its long geometry, the absorption cross-section and linestrength of the laser transition could be directly measured, allowing easier estimate of the emission cross-section than with usual methods relying on fluorescence decay time and quantum efficiency measurements, or a Judd-Ofelt analysis. Our measurements are validated by using McCumber’s reciprocity principle. The small-signal gain spectrum measured in an amplifier experiment matches well the emission cross-section. Order-of-magnitude loss reduction is demonstrated by lowering the temperature to -34°C, implying substantial reduction of the laser oscillation threshold in cold solar-pumping environments.

Device for Real-Time Measuring of Circular Dichroism at Specific Wavelength

Hacob Margaryan, Nelson Tabiryan, Tigran Sargsyan, Petros Gasparyan, Nune Hakobyan, Valeri Abrahamyan, Hakob Chilingaryan, and David Pokhsraryan

Doc ID: 352019 Received 14 Nov 2018; Accepted 19 Jan 2019; Posted 24 Jan 2019  View: PDF

Abstract: We show the opportunity of fabricating device for measuring circular dichroism (CD) in real time, the key element of which is liquid crystal cycloidal diffractive waveplate (CDW). We pay attention that using two charge coupled devices (CCDs) it is basically impossible to measure CD spectra with an accuracy of a few millidegrees. We propose a device for CD measurement on one wavelength, where for light registration two photodetectors are used. This approach allows precise measuring CD with high stability in time. We suppose that developed CD meter can be promising for investigation of fast running processes in bio-objects.

Pancharatnam-Berry optical elements for head-up and near-eye displays [Invited]

Tao Zhan, Yun-Han Lee, Guanjun Tan, Jianghao Xiong, Kun Yin, Fangwang Gou, Junyu Zou, Nannan Zhang, Dongfeng Zhao, Jilin Yang, Shin-Tson Wu, and Sheng Liu

Doc ID: 353161 Received 29 Nov 2018; Accepted 19 Jan 2019; Posted 24 Jan 2019  View: PDF

Abstract: Liquid-crystal (LC) based Pancharatnam-Berry phase optical elements (PBOEs), also known as diffractive wave plates (DWPs), geometric phase optics (GPO) or geometric phase holograms (GPHs), are functional planar structures with patterned orientation of anisotropy axis. Several scientifically interesting yet practically useful electro-optical effects, such as focusing, beam splitting, waveguide coupling, and wavelength filtering, have been realized with PBOEs. Due to high degree of optical tunability, polarization selectivity, nearly 100% diffraction efficiency and simple fabrication process, PBOEs have found widespread applications in emerging display systems, especially virtual/augmented/mixed reality displays and head-up displays. In this review paper, we will describe the basic operation principles, present the device fabrication procedures, discuss the numerical modeling methods, and finally address applications of PBOEs in emerging display systems.

Shaping Airy beams by using tunable polarization holograms

Ulises Ruiz, Teresa Cerda, Gabriella Cipparrone, and Pasquale Pagliusi

Doc ID: 353168 Received 04 Dec 2018; Accepted 19 Jan 2019; Posted 28 Jan 2019  View: PDF

Abstract: The optical beam shaping has emerged as an important tool in optics and photonics applications. Here we present the generation of Airy beams by means of the spatial light modulator (SLM) assisted polarization holography technique. The polarization holograms (PHs) are recorded in a polarization sensitive nematic liquid crystal (NLC) cell. By exploiting advantage of the PHs diffraction properties, such as the achromatic behavior and the high diffraction efficiency, polarization dependent, we generated experimentally Airy beams with diffraction efficiency of 91 % at a wavelength of 633 nm.

Double V-groove dielectric loaded plasmonic waveguide for sensing applications

Amir Habibzadeh-Sharif and Farnaz Jabbarzadeh

Doc ID: 340625 Received 24 Jul 2018; Accepted 14 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: In this study, a novel double V-groove dielectric loaded plasmonic waveguide (DVG-DLPW) structure suitable for sensing applications is proposed and simulated. Two symmetrical V-grooves are cut into the vertical surfaces of the dielectric ridge to increase the interaction of analyte with the waveguide surface and increase sensing depth of surface plasmon polaritons while increasing propagation length of guided modes. Double V-groove dielectric ridge is placed on a graphene surface to take the advantages of using graphene as a sensitivity enhancing material for plasmonic biosensors. A detailed analysis of the sensing and propagation properties of this structure is performed under different device parameters. The results show that under optimal conditions, the proposed plasmonic waveguide demonstrates not only longer propagation length but also a higher sensitivity as compared with conventional dielectric loaded plasmonic waveguide (DLPW) counterpart.

Continuous variable quantum key distribution with multi-mode signals for noisy detectors

Rupesh Kumar, Xinke Tang, Adrian Wonfor, Richard Penty, and Ian White

Doc ID: 348540 Received 17 Oct 2018; Accepted 14 Jan 2019; Posted 15 Jan 2019  View: PDF

Abstract: This paper proposes a multi-mode Gaussian modulated continuous variable quantum key distribution (CV-QKD) scheme able to operate at high bandwidth despite using conventional noisy, coherent detectors. We demonstrate enhancement in shot noise sensitivity as well as reduction in the electronic noise variance of the coherent receiver of the multi-mode CV-QKD system. A proof of concept simulation is presented using multiple modes. This demonstrates an increase in signal to noise ratio (SNR) and secure key rate at various transmission distance with increasing signal modes.

Study of dielectric coatings for broad band operation of surface-emitting semiconductor lasers

Christopher Head, Theo Chen Sverre, Jonathan Woods, Alexander Hein, Markus Polanik, Andrew Turnbull, Edward Shaw, Peter Unger, Anne Tropper, and Vasilis Apostolopoulos

Doc ID: 354725 Received 18 Dec 2018; Accepted 12 Jan 2019; Posted 15 Jan 2019  View: PDF

Abstract: We investigate anti-reflection coating materials for two different operation lasingregimes requiring broad spectral bandwidth. We characterize high-power continuous-wave (CW) wavelength-tunable vertical-external-cavity surface-emitting semiconductor lasers and their passive mode-locking capabilities when using semiconductor saturable absorber mirrors.One laser gain design was investigated with different single dielectric layers as AR-coatings. The dielectric coating materials used were SiO₂, Al₂0₃, Ta₂O₅ and TiO₂. The AR-coating wasdesigned to reduce pump reflection and increase the confinement factor of the micro-cavity.Average power of 4.6 W in CW and a total wavelength-tuning range of 42 nm has been observedwith the SiO₂-coated structure. The shortest pulse of 708 fs was also observed for the SiO₂-coatedstructure, with corresponding CW wavelength-tuning range of 36 nm.

Wavelength Assignment in Quantum Access Networks with Hybrid Wireless-Fiber Links

Sima Bahrani, Osama Elmabrok, Guillermo Curras Lorenzo, and Mohsen Razavi

Doc ID: 347304 Received 02 Oct 2018; Accepted 03 Jan 2019; Posted 03 Jan 2019  View: PDF

Abstract: We propose a low-complexity near-optimal wavelength allocation technique for quantum key distribution access networks that rely on wavelength division multiple access. Such networks would allow users to send quantum and classical signals simultaneously on the same optical fiber infrastructure. Users can be connected to the access network via optical wireless or wired links. We account for the background noise present in the environment, as well as the Raman noise generated by classical channels, and calculate the secret key generation rate for quantum channels in the finite-key setting. This allows us to examine the feasibility of such systems in realistic scenarios when the secret key exchange needs to be achieved in a limited time scale. Our numerical results show that, by proper choice of system parameters for this noisy system, it is possible to exchange a secret key in tens of seconds. Moreover, our proposed algorithm can enhance the key rate of quantum channels, especially in high noise and/or high loss regimes of operation.

Comment on “Research on third-harmonic generation with position-dependent mass in a quantum well” [Journal of the Optical Society of America B, Vol. 35, pages 1408-1414 (2018)]

Emmanuel Paspalakis and Dionisis Stefanatos

Doc ID: 346657 Received 25 Sep 2018; Accepted 15 Nov 2018; Posted 25 Jan 2019  View: PDF

Abstract: We show that the results and conclusions of the paper “Research on third-harmonic generation with position-dependent mass in a quantum well” [Journal of the Optical Society of America B, Vol. 35, pages 1408-1414 (2018)] are incorrect.

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