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Abstract
Photonic quantum information processing and communication demand highly integrated device platforms, which can offer high-fidelity control of quantum states and seamless interface with fiber-optic networks simultaneously. Exploiting the unique quantum emitter characteristics compatible with photonic transduction, combined with the outstanding nonlinear optical properties of silicon carbide (SiC), we propose and numerically investigate a single-crystal cubic SiC-on-insulator (3C-SiCOI) platform toward multi-functional integrated quantum photonic circuit. Benchmarking with the state-of-the-art demonstrations on individual components, we have systematically engineered and optimized device specifications and functions, including state control via cavity quantum electrodynamics and frequency conversion between quantum emission and telecommunication wavelengths, while also considering the manufacturing aspects. This work will provide concrete guidelines and quantitative design considerations for realizing future SiCOI integrated photonic circuitry toward quantum information applications.
© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
1. Introduction
Quantum networks empowering information exchange amongst remote quantum nodes via secure quantum channels are envisioned as the backbone for future pervasive distributed quantum computing and quantum communication [1]. The physical implementation of such networks, especially with scalability, increasingly demands quantum nodes that process quantum states and store them over a significant time period, and quantum channels that distribute quantum information over a long distance with high fidelity and efficiency. Optical photons, as flying qubits, have already been proposed and demonstrated to be among the leading quantum information (qubit) carriers [2,3], because of the unparalleled quantum coherence at room temperature and the compatibility with state-of-the-art fiber-optic communication networks and existing scalable infrastructures. On the other hand, a variety of approaches have been actively pursued toward developing local qubits and quantum nodes, ranging from trapped atoms/ions [4,5,6], superconducting circuits [7,8,9], to linear photonic integrated circuits [10,11]. While remarkable progress has been made in these pursuits, some of these approaches and their systems still face significant engineering and technological challenges, especially in miniaturization and coherent operation at elevated temperatures and in less stringent vacuum or other environments [6,8,10].
Recent advances in materials science and nanotechnology have led to a proliferation of atom-like defect centers (sometimes also called ‘inverted atoms’) in wide-bandgap (WBG) materials [12,13,14], such as nitrogen vacancy (NV) centers in diamond [15], silicon vacancy (VSi) and divacancy (DV) centers in silicon carbide (SiC) [16,17]. These atomic impurities possessing quantized states deep within the bandgap can emit single photons and host optically addressable spin qubits with measured coherence even at room temperature [18,19,20]. The robust quantum coherence, along with the potential in integration and scaling-up, makes them promising candidates as exquisite qubits that can go on-chip. As it is highly desirable to have the quantum emitters, their interfacing transducers, and manipulation mechanisms on the same material platform, considerable effort and advances have been made in the fabrication of such systems [12,13,14]. High-quality wafer-scale device platforms, which permit monolithic integration of solid-state qubits into photonic circuits, coherent quantum control, and efficient quantum frequency conversion to seamlessly interface with the quantum channels, are actively pursued in various relevant materials, including diamond and SiC.
In this work, we propose a cubic SiC-on-insulator (3C-SiCOI) platform, built upon a unique ensemble of important properties that are endowed to 3C-SiC, including the defect quantum emitter (QE) characteristics, excellent nonlinear optical properties, and its wafer-scale, thin-film manufacturability directly on silicon (Si) substrate (the only one amongst the major polytypes of SiC). Different from diamond, which is currently a leading platform for defect-based quantum emitters, SiC (including 3C-SiC) is a non-centrosymmetric crystal that possesses strong second-order nonlinearity [21]. The second-order nonlinear processes, including second harmonic generation (SHG), sum frequency generation (SFG), and difference frequency generation (DFG), are critical schemes toward quantum frequency generation and conversion. While other WBG materials, such as gallium phosphide (GaP) [22], gallium nitride (GaN) [21], and aluminum nitride (AlN) [21], and well known crystalline materials such as lithium niobate (LiNbO3) [23], also have high second-order susceptibilities, they do not readily host suitable quantum emitters with long coherence as those established in diamond or SiC, thus leaving SiC to be a clearly suitable candidate for monolithic integration of quantum emitters with nonlinear photonics on chip.
Fig. 1. Conceptual illustration of 3C-SiCOI integrated photonic circuitry. Cavity quantum electrodynamics (Cavity-QED, Middle) can be explored on this defect-cavity coupled platform. Utilizing the strong second-order optical nonlinearity in 3C-SiC, cavity-enhanced second harmonic generation (SHG, Left) and difference frequency generation (DFG, Right) are proposed to interface the quantum emitters with optical fiber transmission windows for the future quantum network.
Design of quantum nodes with multiple functionalities requires careful accounting of cavity-QE coupling and dispersion engineering over a wide range of wavelengths, with trade-off considerations among multiple coupling domains. Besides optimizing the performance at conventional telecommunication (telecom) wavelength of 1550 nm, we conduct finite-element method (FEM) simulations and design the device functionalities at wavelength aligned with the quantum emission line from 3C-SiC divacancy center (∼1110 nm) and the frequency conversion between quantum emission and telecom wavelength. Encouraged by the recent experimental demonstrations of Purcell enhancement and cavity-enhanced SHG [24,25,26], we further explore the coupling between 3C-SiC microring cavity and defect center toward cavity quantum electrodynamics (cavity-QED) and propose a cavity-enhanced DFG scheme which may lead to entanglement between local qubits at quantum nodes and flying qubits in optical quantum channels (Fig. 1). This comprehensive design work and engineering strategies herein will serve as an important groundwork for future photonic quantum information processing and communication.
2. Engineering the SiCOI stacking
Thin 3C-SiC layers heteroepitaxially grown on Si conveniently bring a suite of advantages in Si-compatible thin film fabrication at wafer scale. Its natural SiC-on-Si stacking nonetheless engenders a practical limitation toward achieving optimal light confinement in epitaxial 3C-SiC films, since Si has a higher index of refraction than SiC (nSi=3.479, nSiC=2.568 at 1550 nm), which induces leakage of the field to Si. Analogous to the prevailing Si-on-insulator (SOI) wafers, high-quality, single-crystal 3C-SiCOI wafers have been developed, in which low-refractive-index silicon oxide (SiO2, nSiO2=1.444 at 1550 nm) serves as the isolation layer and provides preferable dielectric and refractive index contrast. A high index contrast between the SiC core and the SiO2 cladding/buried oxide layers means that light can be well confined inside the SiC waveguide, permitting compact photonic integrated circuits (PICs) with densely spaced micron-scale photonic devices.
We note that a couple of approaches have been attempted in producing hexagonal SiCOI (6H- or 4H-SiCOI) platforms. One is similar to the ‘smart-cut’ SOI technology, where energetic ions are employed to slice thin films of single-crystal 6H- or 4H-SiC bonded to SiO2 on Si substrate [27,28,29]. Another is to directly bond bulk SiC wafer (hundreds of micrometers thick) to a SiO2-topped handle wafer, and then thin the bulk SiC down to target device-layer thickness (a few hundreds of nanometers) by brute-force grinding or alike [24,30,31]. These have yield ranging from ∼cm-sized chips to portions of wafers limited by the bonding fidelity, and the fraction of resulting 6H- or 4H-SiCOI with uniform SiC thickness may be below 10% [31]. Now turn to 3C-SiC, thanks to the available thin-film epitaxy techniques, the thickness of 3C-SiC device layer can be directly controlled during the growth, resulting in production of 3C-SiCOI with thickness variation of ∼100 nm across a 2×2 inch chip [32]. Recently, implantation-free and wafer-bonding-free 4-inch 3C-SiCOI wafers have been produced via a novel wafer-construction technique with benefits and advantages of low cost, high yield, and minimized the damage of single-crystal layers [33], paving the way toward foundry processing of integrated quantum photonic devices.
The 3C-SiCOI platform designed in this work possesses a stacking order of SiO2/SiC/SiO2/Si from top to bottom, as illustrated in the insets of Fig. 2(a) & 2(b). To minimize the leakage to the high-refractive-index Si substrate and facilitate large optical confinement in the SiC waveguide, the thickness of the buried SiO2 layer tBOX has been optimized based on two-dimensional (2D) simulations performed in COMSOL Multiphysics. When tBOX is significantly smaller than the working wavelength λ, the light leakage can be clearly visualized from the simulated electric-field distribution of the fundamental quasi-transverse-electric (quasi-TE00) mode inside the SiC waveguide (Fig. 2(a)). The complex effective refractive index neff and attenuation constant
which are associated with the propagation loss, have been calculated to further evaluate the influence of the SiO2 layer quantitatively. As shown in Fig. 2(c), the propagation loss decreases rapidly as the thickness of the SiO2 layer increases, and less loss is expected for the modes at a shorter wavelength. For a SiO2 BOX with thickness greater than 0.6 µm, the attenuation constant is less than 1.6 cm−1 for both λ=1110 nm and 1550 nm, corresponding to an experimental value from a previous report on 4H-SiCOI waveguide [28]. A similar analysis has been conducted to investigate the influence of SiO2 cladding thickness tclad. A 3C-SiCOI stacking with tBOX=tclad=3 µm is employed for the following device design (Fig. 2(b)), of which attenuation constant is calculated to be as small as 10−6 cm−1 (Fig. 2(d) & 2(e)), to exclude the leakage to the Si substrate as a primary source of loss. With advances in micro/nanofabrication, sub-nanometer roughness on top surface and low nanometer sidewall roughness have been achieved on 3C-SiC films; therefore, the loss from interface scattering is expected to be mitigated [32]. The remaining loss sources in practical devices may arise from the scattering and absorption of defects and unintentional doping in the 3C-SiC thin films.Fig. 2. Design of 3C-SiCOI stacking. Electric-field distribution for quasi-TE00 mode at 1550 nm of a rectangular-cross-section 3C-SiC waveguides with the same cross-sectional dimension wwg×tSiC=750 nm×475 nm but on (a) A 500nm-thick and (b) A 3µm-thick SiO2 ‘BOX’ (buried oxide) layer, respectively. The SiO2 cladding thickness tclad is set as 3µm, and the yellow step curves inserted in panels (a) and (b) represent the relative refractive index profile of each material layer (nSi>nSiC>nSiO2). (c) Plots of attenuation constant α as a function of SiO2 thickness tBOX for the quasi-TE00 (Square) and quasi-TM00 (Triangle) modes of SiC waveguides with a fixed cross-sectional dimension of 750 nm×475 nm at 1110 nm (Orange and Olive) and 1550 nm (Red and Wine). Black dashed line: α=1.6 cm−1, equal to an experimental value from a previous report [28]. 2D color maps and contour lines of attenuation constant α as (d) A function of tBOX and tSiC and (e) A function of tclad and tSiC, respectively.
3. Mode confinement and cavity-QED
Among the discovered defect-based quantum emitters in SiC, neutral divacancy (DV0) center, consisting of a silicon vacancy adjacent to a carbon vacancy, is considered a promising qubit candidate for quantum communication technologies, due to the optically addressable spin states, long-lived electron spin coherence, and available defect engineering techniques [34,35]. Particularly, DV0 in 3C-SiC associated with a single photon emission of 1.12 eV (λ∼1110 nm in wavelength) is reported to have a millisecond Hahn-echo spin coherence time, which is among the longest measured in naturally isotopic solids [35]. In a cavity-QED system, photonic cavities with high quality (Q) factor and small effective mode volume (Veff) are desirable to increase the rate of photon emission, to enhance the ratio of single photon emission into zero-phonon line (ZPL), hereby to achieve strong coherent interaction between the optical transition from defect center and the cavity modes at the single quantum level. Extensive attention has been attracted to develop 3C-SiC nano/microcavities over the past decade [32,36,37,38,39,40,41]; however, most state-of-the-art demonstrations are focused on cavity resonance in the telecom band, which are not aligned with the ZPL wavelength of defect states in SiC.
Therefore, we perform finite-element eigenfrequency simulations to explore the whispering-gallery modes (WGMs) in 3C-SiC microring cavity at both quantum emission (1110 nm) and telecom (1550nm) wavelengths. By assuming azimuthal symmetry of the microring structures, only a 2D cross-section of the microring is simulated, via employing the 2D axisymmetric space dimension in COMSOL. Figure 3(a) presents the electric-field distribution for quasi-TE00 mode of a microring cavity, with radius rring of 3 µm, width wring of 750 nm, and thickness tSiC of 500 nm. The submicron cross-sectional dimension investigated here is beneficial to both strong light confinement for cavity-QED and efficient dispersion engineering for frequency conversion (discussed in the section below). With the same geometric settings, the microring can provide better confinement for the modes at 1110 nm, compared to the ones at 1550 nm. Radiation loss due to sharp bending can be revealed in electric-field distribution of quasi-TE00 mode at 1550 nm, for a microring with a relatively small radius of 3 µm (Fig. 3(a), Bottom). Further analysis of radiation-limited quality factor
where k is the complex wave number of the resonant cavity mode, helps to determine the minimum radius to be 1.5 µm and 3 µm for a microring to support fundamental modes (both quasi-TE00 and quasi-TM00) with Qrad∼105 at 1110 nm and 1550 nm, respectively (Fig. 3(b)). Such a Q factor is comparable with the record high experimental values measured from 3C-SiC microring or microdisk cavities [32]. When the ring radius exceeds 6 µm, the simulated Qrad gradually saturates around 1017 for the fundamental modes at 1110 nm. The corresponding effective mode volume is calculated asFig. 3. Whispering-gallery modes of 3C-SiC microring cavity at quantum emission and telecom wavelengths. (a) Electric-field distribution for quasi-TE00 mode of a microring cavity (rring=3 µm, wring=750 nm, tSiC=500 nm) around 1110 nm (Top) and 1550 nm (Bottom), respectively. The inserted yellow step curve represents the relative refractive index profile of SiO2/SiC/SiO2 layers (nSiC>nSiO2). (b) Radiation-limited quality factor Qrad and (c) Effective mode volume Veff as functions of microring radius rring for the quasi-TE00 (Square) and quasi-TM00 (Triangle) modes around 1110 nm (Orange and Olive) and 1550 nm (Red and Wine), calculated for microrings with a fixed cross-sectional dimension wring×tSiC=750 nm×500 nm. Black dashed lines: Qrad=105, 106, 107, corresponding to the record high Q factors measured from 3C-SiC [32], 4H-SiC [24], and a value at which the radiation loss will not be the dominant loss mechanism, respectively. (d) Purcell factor as a function of Q and Veff for cavity modes around 1110 nm (Yellow to Orange) and 1550 nm (Pink to Red).
A critical challenge towards realizing efficient enhancement and strong coupling between the emission from a defect center and a cavity photon lies in coinciding the dipole moment and the maximum electric field both spatially and spectrally. The microring cavities studied in this work possess submicron cross-sections, and the optical modes cover nearly the entire volume of the ring (Fig. 3(a)). Recent advances in density and spatial control of DV0 defects in 3C-SiC via ion implantation permit isolated single defect within the microring cavity [34,35]. The degree of freedom in mode families, which offers a variety of electric field distributions, can facilitate good overlap between the point defect and a certain optical mode. Moreover, the unique whispering-gallery characteristics of microring design support multiple cavity resonances within each mode family and empower broad-range tunability with azimuthal mode numbers, which cannot be attained in photonic crystal cavities. Figure 4(a) illustrates a DV0 center embedded inside a 3C-SiC microring cavity. The cavity resonance can be flexibly engineered around the quantum emission wavelength by finely tuning the device radius rring and azimuthal index m (mλ=2πrringneff). As shown in Fig. 4(b), the resonance condition at 1110 nm can be matched by a number of cavity modes with different device radii (7 matching points within a 400 nm radius range for quasi-TE00 mode, and even more for quasi-TM00 and higher-order modes). It suggests that the microring design can offer considerable dimensional tolerance against the microfabrication imperfections.
Fig. 4. Coupling between divacancy defect DV0 and microring cavity. (a) Schematic illustration of DV0 center embedded in a 3C-SiC microring, lattice representation and energy level diagram of the DV0 center (not in scale). (b) 2D color map and lines of effective refractive index ℜe(neff) as a function of ring radius rring and azimuthal mode index m for the quasi-TE00 mode, based on microrings with a fixed cross-sectional dimension wring×tSiC=750 nm×500 nm. Brown lines: Solutions for resonance condition mλ=2πrringneff. Orange dashed line: Resonance wavelength λ=1110nm. Black dashed lines and arrow: Free spectral range FSR=12 nm. Plots of (c) Cavity decay rate κ/2π, (d) Coherent coupling rate g/2π, and (e) Ratio between the calculated coupling rate g and the maximum decay rate of the defect-cavity system max(γ,κ), as a function of ring radius rring for the quasi-TE00 (Orange Square) and quasi-TM00 (Olive Triangle) modes around 1110 nm, calculated by assuming the spontaneous emission lifetime of DV0 center τsp=19ns [35]. Black dashed line: κ/2π=2 GHz, equal to the dephasing rate of DV0 center γ/2π as the benchmark value.
To further translate the cavity mode analysis performed above to the standard parameters studied in cavity-QED, we calculate the cavity decay rate ${\kappa / {2\pi = {\omega / {4\pi Q}}}}$ and the coupling rate between quantum emission and cavity mode
4. Second-order nonlinear frequency conversion
In solid-state-qubit-based quantum photonic circuits, it is advantageous to be able to arbitrarily convert the frequencies of photons, for interfacing QEs of different wavelengths and for interfacing them with the maximum detection/transmission efficiency windows. For instance, the telecom wavelength inputs (1550 nm) need to be up-converted to visible wavelength photons via second harmonic generation (SHG) or sum frequency generation (SFG) to pump the defect centers in SiC. A shorter wavelength photon (1110 nm) emitted from the defect center will interact with other single photons to fulfill certain computational or sensing functions. The resulting photons need to be converted back to telecom wavelengths via difference frequency generation (DFG) for transmission over the fiber-optic network. Finally, SHG/SFG can be used to up-convert the photons for efficient detection on Si avalanche photodetectors, of which the maximum detection window is around 700 nm. Here, we propose to exploit second-order nonlinear processes to achieve the aforementioned frequency conversion on the SiCOI platform, considering the exceptional quadratic (χ(2)) nonlinearity possessed by SiC [21], which is absent in centrosymmetric crystals such as Si and diamond. Furthermore, the quantum nature of photons can be preserved during second-order nonlinear processes theoretically [43].
To realize efficient second-order frequency conversion, frequency and phase matching have been performed on microring cavities, following the dispersion engineering scheme proposed in previous work [44]. The geometric dispersion of the optical modes in a device is fully determined by the SiC thickness tSiC, ring width wring, and ring radius rring, which can balance the intrinsic material dispersion and allow for phase matching across a wide frequency separation. To minimize the computation power consumed in the parametric sweeps, we first carry out the simulations on a straight waveguide model with the first two parameters to estimate the frequency mismatch. Submicron tSiC and wring chosen here are beneficial to achieving high confinement (as discussed above) and enhancing the effective nonlinearity, which is highly dependent on the effective mode volume. With the estimated range of tSiC and wring, we then run full simulations on a microring model with the radius fixed at 6 µm, of which radiation loss is not expected to be the dominant loss mechanism, to resolve the possible optical modes around the targeted wavelengths (within one FSR).
For the cavity-enhanced SHG process, the energy conservation condition can be satisfied by setting the input as 1550 nm and the output as 775 nm (ω775=2ω1550, Fig. 5(a)). However, due to the sizable dispersion in the intrinsic refractive index of the material, it is impracticable to accomplish the conversion between fundamental modes. The mode matching between quasi-TE00 at 1550 nm and quasi-TE20 (or quasi-TM20) at 775 nm has been explored, because the favorable complex electric-field profiles can lead to relatively large overlap integral that quantifies the coupling efficiency (Fig. 5(b))
The frequency mismatch is calculated as
and the phase matching condition Δω=0 can be translated into the effective refractive index matching n775=n1550. The possible sets of waveguide geometric parameters that meet such requisite are indicated in Figs. 5(c) and 5(d) for quasi-TE20 and quasi-TM20 at 775 nm, respectively. For the microring geometry, additional phase matching of the azimuthal momentum is required. Figure 5(e) exhibits the frequency mismatch between quasi-TE00 at 1550 nm and quasi-TE20 at 775 nm calculated based on the microring model, of which mode numbers are set as m775=2m1550=102. It is noted that the bending effect yields additional geometric dispersion and offsets the targeted geometry settings from the ones determined in straight waveguide simulations. For instance, at a SiC thickness tSiC=400 nm, the targeted waveguide width is ∼815 nm, but the corresponding microring width is ∼843 nm for quasi-TE20 at 775 nm.Fig. 5. Frequency and phase matching for cavity-enhanced second harmonic generation (SHG). (a) Scheme for cavity-enhanced SHG with ω=2πc/(1550 nm) and 2ω=2πc/(775 nm). (b) Electric-field distribution for quasi-TE00 mode at 1550 nm and quasi-TE20 at 775 nm of a 3C-SiC waveguide (wwg=875 nm, tSiC=475 nm), and the spatial overlap of these two modes prior to integrating over the volume. Dispersion engineering for frequency and phase matching, where frequency mismatch Δω=2n1550ω1550/n775−ω775 is plotted as a function of SiC thickness tSiC and (c) & (d) Waveguide width wwg or (e) Microring width wring. The simulations in (c) & (d) are based on a straight waveguide model (no bending effect) for conversion (c) From quasi-TE00 mode at 1550 nm to quasi-TE20 at 775 nm and (d) From quasi-TE00 mode at 1550 nm to quasi-TM20 at 775 nm, respectively. The simulation in (e) is based on a microring model (rring=6µm), and the azimuthal mode numbers are fixed to be m1550=51 for quasi-TE00 mode at 1550 nm and m775=102 for quasi-TE20 at 775 nm. Black dashed lines: Δω=0.
In parallel, the frequency and phase matching conditions have been engineered for cavity-enhanced DFG, by assuming the pump, idler, and signal wavelengths as 647 nm, 1110 nm, and 1550 nm, respectively (ω647-ω1110=ω1550, Fig. 6(a)). Such DFG scheme is proposed and investigated here rather than the regular conversion process among 1110 nm, 1550 nm, and 3910 nm (ω1110=ω1550-ω3910) [24], given the availability of high-power laser diode and better optical confinement at 647 nm. More importantly, this scheme may initiate parametric down-conversion and the signal (1550 nm) and idler (1110) photons are naturally entangled. The mode matching among quasi-TE00 modes at 1550 nm and 1110 nm and quasi-TM20 at 647 nm is simulated based on a microring model with radius rring=6 µm and mode numbers m647=m1110+m1550=79 + 51 = 130 (Fig. 6(b)). The frequency mismatch is calculated as
Fig. 6. Frequency and phase matching for cavity-enhanced difference frequency generation (DFG). (a) Scheme for cavity-enhanced DFG with ωp=2πc/(647 nm), ωi=2πc/(1110 nm), and ωs=2πc/(1550 nm). (b) Electric-field distribution for quasi-TE00 modes at 1550 nm and 1110nm and quasi-TM20 at 647 nm of a 3C-SiC microring cavity (rring=6 µm, wring=685 nm, tSiC=475 nm), and the spatial overlap of these three modes prior to integrating over the volume. Dispersion engineering for frequency and phase matching, where frequency mismatch Δω=(n647ω647-n1110ω1110)/n1550−ω1550 is plotted as a function of SiC thickness tSiC and (c) & (d) Waveguide width wwg or (e) Microring width wring. The simulations in (c) & (d) are based on a straight waveguide model (no bending effect) for conversion (c) From quasi-TE20 at 647 nm to quasi-TE00 modes at 1110 nm and 1550 nm and (d) From quasi-TM20 at 647 nm to quasi-TE00 modes at 1110 nm and 1550 nm, respectively. The simulation in (e) is based on a microring model (rring=6 µm), and the azimuthal mode numbers are fixed to be m1550=51 for quasi-TE00 mode at 1550 nm, m1110=79 for quasi-TE00 mode at 1110 nm, and m647=130 for quasi-TM20 at 647 nm. Black dashed lines: Δω =0.
The cavity-enhanced SHG and DFG schemes proposed above are based on waveguides and microring resonators with rectangular cross-sections. Similar design guidelines can be derived for devices with less-vertical, tilted sidewalls due to fabrication imperfections of low-anisotropic reactive ion etching (RIE).
5. Conclusions
In this design work, we have introduced integrated design on a single-crystal 3C-SiCOI wafer that is Si-compatible and currently available in 4-inch wafer size, as an emerging platform for enabling large-scale integrated quantum photonic circuits. By performing a series of FEM simulations, the material stacking of 3C-SiCOI has been optimized, and the propagation loss due to leakage to the high-refractive Si substrate can be efficiently suppressed by applying a buried oxide layer thicker than 3 µm. Considering the excellent defect-based quantum emitter (QE) characteristics of SiC and the technical readiness to achieve high-Q optical cavities, cavity-QED has been explored in a microring cavity-QE coupled system. A maximum Purcell factor approaching 103 and strong cavity-QE coupling can be predicted as the Q factor of the microring with submicron cross-section exceeds 105. Furthermore, taking advantage of the substantial χ(2) susceptibility and wide transparency window over the visible and near-infrared spectral range, cavity-enhanced SHG and DFG schemes have been proposed and numerically investigated for implementing quantum frequency conversion and interfacing the quantum emitters in 3C-SiC with the maximum fiber-optic transmission window. The methodology and quantitative design metrics developed in this paper will facilitate the realization of wafer-scale multifunctional integrated SiC quantum photonic circuits that form the fundamental building blocks to construct a scalable quantum photonic network.
Funding
National Science Foundation (NSF) via the EFRI ACQUIRE program (EFMA-1641099) and its supplemental funding through the Research Experience and Mentoring (REM) program.
Acknowledgments
We thank Dr. Xiyuan Lu from NIST for helpful discussions.
Disclosures
The authors declare no conflicts of interest.
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