Here we design and fabricate a hybrid surface plasmon polarities (SPP) waveguide on the silicon-on-insulator (SOI) photonics platform. The designed hybrid SPP waveguide is composed of a metal ridge, an air gap, and a silicon ridge. We simulate the mode characteristics in the structure and design the waveguide with a wide air gap that can simplify the fabrication process and maintain the advantages of the hybrid SPP mode. The performance of ultrahigh-bandwidth data transmission through the proposed waveguide is then investigated using 161 wavelength-division multiplexing (WDM) channels, each carrying a 11.2-Gbit/s orthogonal frequency-division multiplexing (OFDM) 16-ary quadrature amplitude modulation (16-QAM) signal. The bit-error rates (BERs) of all 161 channels are less than 1e-3. The favorable results show the prospect of on-chip optical interconnection using the proposed hybrid SPP waveguide.
© 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Integrated plasmonic devices have gained accumulating attentions during the last decade for their great potential for on-chip optical communication and signal processing . Surface plasmon polaritons (SPP), attributed to the interaction between the surface charges and the electromagnetic field at a metal-dielectric interface, can considerably confine light in subwavelength scale and enhance local electric field [2–7]. Compared with traditional dielectric waveguides, SPP waveguides are able to increase integration of devices, but they suffer from inherent tradeoff between metal-induced propagation loss and the optical mode confinement especially when high-permittivity dielectric materials such as semiconductors are involved [8–11]. To deal with the problem, the hybrid SPP waveguides consisting of metal, oxide and semiconductor have been put forward on account of their capabilities of combining sundry superiorities of ultra-small mode volume, relatively low transmission loss, efficient coupling with dielectric waveguides, and complementary metal oxide semiconductor (CMOS) compatibility [12–16]. Owing to those advantages, hybrid SPP waveguides have been studied in many applications such as bends [17–19], lasers [13, 20], polarization beam splitter [21, 22], modulators , couplers , sensors , etc. However, the reported researches of hybrid SPP waveguides mainly focus on the nanometer thickness of oxide layer, which benefits ultra-small mode volume and strong local electric intensity but increases the difficulty of fabrication [26–28]. For instance, air layer or gap is quite effortless to be affected by the roughness introduced in the fabrication process. When the thickness of air gap is small enough, the metal layer may touch silicon layer owing to the roughness [26, 27]. Therefore, it is necessary to design new structure to combine simple fabrication process and superiorities of hybrid SPP waveguide.
Besides, optical interconnection based on photonic integrated circuits (PICs) providing relaxed interconnection latency, wide bandwidth, low energy consumption and immunity to mutual interference effects, is considered as the promising technology to realize high-speed very large scale integration (VLSI) interconnection networks [29–32]. Several interesting and important developments of on-chip optical interconnection have been addressed in these prior art works: 1) transmission of 1.28-Tbit/s data stream (32 wavelengths × 40-Gbit/s) on-off keying (OOK) signals in a silicon waveguide with relatively low penalty ; 2) transmission of 170-Gbit/s OOK signals in an erbium-doped waveguide amplifier ; 3) 40-Gbit/s differential phase-shift keying (DPSK) transmission through a silicon microring switch . However, the present reports rarely pay attention to on-chip high-speed optical interconnections in hybrid SPP waveguide. Considering the numerous advantages of hybrid SPP waveguides, a laudable goal would be to implement ultrahigh-bandwidth data transmission in hybrid SPP waveguides.
In this paper, we design and fabricate a hybrid SPP waveguide with wide air gap on the Silicon-on-insulator (SOI) photonics platform . The air gap between metal ridge and silicon waveguide is 100 nm while the width of silicon waveguide is 300 nm, which can simplify the fabrication process and maintain the advantages of hybrid SPP waveguide. Two tapers are used to connect the hybrid SPP waveguide with traditional dielectric waveguides to effectively couple hybrid SPP mode with dielectric mode. The concept of on-chip optical interconnection using hybrid SPP waveguide is shown in Fig. 1 consisting of four primary components: laser source, optical modulator, hybrid SPP waveguide and photo detector . The laser source continuously generates carrier waves coupled to the modulator. The optical modulator is used to modulate the carrier waves and load the signals produced by an electrical logic cell on them. The hybrid SPP waveguide can transmit the modulated carrier waves from optical modulator to photo detector. The photo detector generates current proportional to the intensity of carrier waves and sends the signal to another electrical logic cell, realizing a complete optical interconnection process. Then we experimentally investigate the wavelength division multiplexing (WDM) transmission of 1.8-Tbit/s orthogonal frequency division multiplexing (OFDM) 16-quadrature-amplitude-modulation (QAM) aggregate traffic through the suggested waveguide with 11.2 Gbit/s per 161 channels. The bit-error rate (BER) is measured for comprehensive evaluation of transmission performance. The ultrahigh-bandwidth low penalty transmission of OFDM 16-QAM signals is demonstrated in the experiment.
2. Mode characters in hybrid SPP waveguide
The geometry of the proposed hybrid SPP waveguide shown in Fig. 2(a) consists of a gold ridge near a silicon waveguide with a narrow air gap between them on the top of BOX layer. Figure 2(b) depicts the distributions of electric field x component |Ex| of the modes in hybrid SPP waveguide calculated by the finite-element analysis method with different waveguide width w and air gap g at wavelength λ = 1550 nm. For g in nanometer scale, for example g = 20 nm, the dielectric mode is strongly coupled to the SPP mode, and electric field is mainly confined inside the air gap instead of silicon waveguide regardless of the varying of silicon waveguide width. For large g, for example g = 100 nm, the distribution of electric field is sensitive to the width of silicon waveguide. When w is decreasing from 500 nm to 300 nm, the coupling strength between dielectric mode and SPP mode is rising and the concentration area of electric field is transferring from silicon waveguide to air gap. The strong electric field confinement in the air gap region could be seen as the superposition of discontinuity of electric field x component Ex at the silicon-air interface and electric field at the metal-air interface. Here we define the type of mode whose electric field is confined in silicon waveguide as dielectric mode and the mode whose electric field is concentrated in air gap as hybrid SPP mode. Therefore, hybrid SPP waveguide parameters such as w and g can determine the types of modes in the waveguide, such as dielectric mode or hybrid SPP mode.
In order to further understand the characteristics of modes in hybrid SPP waveguide, we numerically calculate the effective index and transmission loss of the mode depending on silicon waveguide width w and air gap g, plotted in Figs. 3(a) and 3(b), respectively. As w is changing from 500 nm to 250 nm, the disparity of effective index and loss between difference g is increasing. The results indicate that when air gap g is increasing, more electric field is distributed in air especially silicon waveguide is small (w < 350 nm). Moreover, in spite of the rising of transmission loss, the growth rate of loss is decreasing as air gap g is larger. Using a coupled mode theory, the hybrid SPP mode Ψ supported in the waveguide can be approximately seen as a superposition of the dielectric mode Ψd and SPP mode ΨSPP ,12]Fig. 3(a). While nd is mainly influenced by w of dielectric waveguide, a wider w means a larger nd because more electric field is distributed in dielectric waveguide. nSPP is related to the permittivities of metal and air medium near the surface of metal ridge. Figure 3(c) illustrates the mode character |b|2 as functions of silicon waveguide width at different air gap g. When the value of w remains constant, the mode character is increasing with the reducing value of g. While w is decreasing, hybrid SPP mode is becoming more and more SPP-like under the same value of g. Furthermore, for g = 100 nm, w = 500 nm, the value of mode character |b|2 is nearly zero which can be seen only dielectric mode exists in the waveguide. For g = 100 nm, w = 300 nm, mode character |b|2 improves to 0.176 which is even larger than that of g = 20 nm, w = 500 nm. This phenomenon theoretically verify the possibility that hybrid SPP mode of large air gap can be more SPP-like than that of nanoscale g.
3. Design and fabrication of hybrid SPP waveguide
Figure 4(a) exhibits the schematic diagram of the proposed hybrid SPP waveguide connecting with input/output dielectric waveguides using two coupling tapers. The width of silicon waveguide w is 300 nm and air gap g is 100 nm in consideration of relatively low transmission loss and high mode character according to Fig. 3. Figure 4(b) displays the distribution electric field x component Ex in the propagation direction using finite difference time domain (FDTD) method. One can effortlessly indicate from Fig. 4b that dielectric mode in dielectric waveguide can successfully convert to hybrid SPP mode and experience the reverse process in tapers. The coupling ability can be taken for the changing of taper width driving more electric field distributed in air gap and coupling with SPP mode. To further analyze the coupling loss caused by tapers, Fig. 4(c) shows the simulated transmission of a 10 μm hybrid SPP waveguide depending on the wavelength with different tap length Ltap. As Ltap is decreasing, transmission is becoming worse which manifest an increasing coupling loss of tap. Besides, the transmission loss of long-wavelength region (>1600 nm) is larger than that of short-wavelength region (<1500 nm) in view of more electric field concentrated in air gap coupling with SPP mode as wavelength is increasing. In addition, when Ltap is longer than 2 μm, transmission loss is less than 1 dB from λ = 1500 nm to 1600 nm which is beneficial to data transmission in C-band.
On the basis of theoretically simulation of proposed hybrid SPP waveguide, we fabricate the waveguide on a SOI piece using several simple steps shown in Fig. 5(a). Firstly, two 70 nm thick vertical coupling gratings with period of 620 nm are generated on a silicon-on-insulator (SOI) piece using electron-beam lithography (EBL) followed by induced coupled plasma (ICP) etching. Then a 220 nm thick silicon waveguide connecting the gratings is fabricated using EBL overlay technology and ICP etching. In the end, a 10 nm thick nickel layer and a 210 nm thick gold ridge are evaporated on the top of buried oxide (BOX) layer adjoining the silicon waveguide in succession by electron beam evaporation (EBV) after the metal evaporation window is open using the same EBL overlay technology. Figure 5(b) exhibits the optical micrograph of a fabricated hybrid SPP waveguide device. The hybrid SPP waveguides are in the center of the whole waveguides with two 2.5-μm-long tapers, as displayed in Fig. 5(c). Figure 5(d) depicts the details of air gap in a hybrid SPP waveguide. To coupling light between hybrid SPP waveguides and optical fibers, vertical coupling gratings are added at the ends of the waveguides shown in Fig. 5(e). The measured transmission loss of a 10-μm and a 20-μm long hybrid SPP waveguide are 0.45 dB and 1.85 dB at wavelength λ = 1550 nm respectively. One can see from Fig. 5(d) that the width of silicon waveguide is 270.5 nm and the air gap is 46.6 nm, which are not quite agreement with designed ones. The difference can be considered to be caused by the error in the fabrication process. To support the fabricated hybrid SPP waveguide, structure with fabricated parameters is also simulated, as plotted in Figs. 5(f) and 5(g). One can indicate from Figs. 5(f) and 5(g) that the hybrid SPP waveguide with fabricated parameters can successfully transmit hybrid SPP mode. It is worth mentioning that the simulated transmission loss through the hybrid SPP waveguide in Fig. 5(g) is lower than measured one. This can be explained that the transmission loss is measured by calculating the difference between the power recorded at the output coupling grating side of hybrid SPP waveguide and the reference waveguide. The reference waveguide contains two coupling gratings (width: 12 μm, period: 620 nm), two tapers (length: 250 μm), and a long narrow waveguide (width: 500 nm wide, length: 1250 μm), which are the same as those of samples containing hybrid SPP waveguide. To measure the transmission loss, a light source followed by a coupler and a power meter is connected to a lens fiber at the input coupling grating side. At the output coupling grating side, a lens fiber followed by a power meter is used to record the value of output power. The value on the power meter at the input coupling grating side maintains constant in the course of measurement. The measured total transmission loss of reference waveguide is approximately 12 dB. The fabrication error may induce disturbance on reference waveguide that the measured power at the output coupling grating side may lower than ideal one.
4. Data transmission in hybrid SPP waveguide
Then, we investigate the suitability of data transmission through fabricated hybrid SPP waveguide with OFDM 16-QAM signals by generating a 1.8-Tbit/s data stream, composed of 161 11.2-Gbit/s wavelengths. The experimental setup is shown in Fig. 6. At the transmitter side, the outputs of seven external cavity lasers (ECLs) are injected to two polarization maintain optical couplers (PMOC) and then combined by two phase modulators (PM). Each ECL sends out a beam of specific wavelength where it appears 23 sidebands after the beam is modulated by PMs Therefore the number of all channels we need is 161 (7 × 23). The outputs of two PMs are connected with polarization controllers (PC) and then joined the erbium-doped fiber amplifiers (EDFA) whose outputs are collected by a wavelength selective switch (WSS). After transmitting from the WSS and an EDFA, all of 161 channels are modulated by an optical I/Q modulator. 10 GS/s arbitrary waveform generator (AWG) is employed to produce single side band electrical signals, which are subsequently fed into the optical IQ modulator. After the IQ modulator, 1.8-Tbit/s OFDM 16-QAM signal is generated. The OFDM 16-QAM signals which are amplified by an EDFA are coupled from fiber to silicon waveguide by vertical grating coupler. Following the silicon waveguide, the signal is amplified by EDFA. A variable optical attenuator (VOA) is employed to adjust the optical signal-to-noise ratio (OSNR). At the receiver side, a local oscillator is used to mix the received signal in a polarization-diversity coherent receiver. The two RF signals corresponding to I/Q components are injected into a Tektronix real-time scope and processed off-line with a MATLAB program.
The output spectrum after the hybrid SPP waveguide propagation is plotted in Figs. 7(a) and 7(b). Figures 7(c) and 7(d) show the BER performance for all 161 channels through the 10 μm hybrid SPP waveguide. One can clearly see that all 161 channels achieve BER less than 1e-3 (7% forward error correction (FEC) threshold). Figure 7(e) plots the measured BER performance curves for λ1 = 1548.195 nm and λ2 = 1551.801 nm channels. One can indicate from Fig. 7(e) that the observed optical signal-to-noise ratio (OSNR) penalty of 10 μm long hybrid SPP waveguide is 0.9 dB while 20 μm long hybrid SPP waveguide is 3.4 dB at a BER of 1e-3, suggesting the impact of transmission loss on signal quality. Figures 7(f) and 7(j) display the measured 16-QAM constellations of back-to-back (B-to-B), 1533.90 nm, 1549.28 nm, 1552.89 nm and 1565.84 nm respectively.
5. Discussion and conclusion
We have designed and fabricated a vertical metal-air-silicon hybrid SPP waveguide using a wide air gap. Compared with the present hybrid SPP waveguides using thin oxide layers (< 50 nm), there are several conspicuous advantages of the proposed waveguide: 1) replacing the oxide layer with air gap, it does not have to deposit the oxide layer with existing fabrication technology, meaning a simpler fabrication process; 2) as is shown in Fig. 3(a), the effective index of hybrid SPP mode is reducing rapidly with air gap increasing, which is considerably important for on-chip interconnection because the propagation speed of mode in wide-air-gap hybrid SPP waveguide is faster than that in thin-oxide-layer hybrid SPP waveguide and the signals carried in wide-air-gap hybrid SPP waveguide would be arrived in receiver earlier; 3) as is plotted in Fig. 3(b), loss induced by metal absorption is decreasing with air gap increasing, indicating the improvement of signal quality using wide-air-gap hybrid SPP waveguide.
In addition to the designed hybrid SPP waveguide, another structure called slot waveguide with air gap can also be used to realize data transmission [39, 40]. Those two kinds of waveguides have similar structures and can both confine light in the air gap. Although slot waveguide has lower transmission loss compared to designed hybrid SPP waveguide, the designed hybrid SPP waveguide has some extra features. The designed hybrid SPP waveguide is composed of metal ridge, air gap, and silicon ridge, which takes up less space to confine light than the slot waveguide does. Because light attenuate rapidly inside the metal. In addition, the hybrid SPP waveguide can be used to design waveguide bends with small radius, which can increase the flexibility of photonic circuits design and improve the integration level [18, 19].
In summary, a kind of hybrid SPP waveguide with simple fabrication process and favorable mode character is proposed. The features of designed hybrid SPP waveguide such as subwavelength confinement and local field enhancement in the air gap can be applied in on-chip data transmission, which is then experimentally investigated. The favorable simulated and experimental results show the possibility of establishing a high-speed on-chip optical interconnection using the proposed hybrid SPP waveguides with various advantages discussed above.
National Natural Science Foundation of China (NSFC) (61761130082, 61222502, 11574001, 11774116, 11274131); Royal Society-Newton Advanced Fellowship; National Basic Research Program of China (973 Program) (2014CB340004); National Program for Support of Top-notch Young Professionals; Yangtze River Excellent Young Scholars Program; Program for New Century Excellent Talents in University (NCET-11-0182).
The authors thank Qi Yang, Ming Luo, Chao Li and Dequan Xie at State Key Laboratory of Optical Communication Technologies and Networks and Chengcheng Gui, Shuhui Li, Shi Chen, Jun Liu, Yifan Zhao, Nan Zhou, Andong Wang and Long Zhu at Huazhong University for Science and Technology for their technical supports and helpful discussions in the device fabrication and experiments. The authors thank the Center of Micro-Fabrication and Characterization (CMFC) of Wuhan National Laboratory for Optoelectronics (WNLO) for the support in the manufacturing process on silicon photonics platform. The authors also thank the facility support of the Center for Nanoscale Characterization and Devices of WNLO.
References and links
1. R. Zia, J. A. Schuller, A. Chandran, and M. L. Brongersma, “Plasmonics: the next chip-scale technology,” Mater. Today 9(7), 20–27 (2006).
2. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [PubMed]
3. E. Ozbay, “Plasmonics: merging photonics and electronics at nanoscale dimensions,” Science 311(5758), 189–193 (2006). [PubMed]
4. J. A. Schuller, E. S. Barnard, W. Cai, Y. C. Jun, J. S. White, and M. L. Brongersma, “Plasmonics for extreme light concentration and manipulation,” Nat. Mater. 9(3), 193–204 (2010). [PubMed]
5. H. Raether, “Surface plasmons on smooth surfaces,” in Surface plasmons on smooth and rough surfaces and on gratings (Springer, 1988), pp. 4–39.
6. A. Ishikawa, S. Zhang, D. A. Genov, G. Bartal, and X. Zhang, “Deep subwavelength terahertz waveguides using gap magnetic plasmon,” Phys. Rev. Lett. 102(4), 043904 (2009). [PubMed]
7. H. Choi, D. F. Pile, S. Nam, G. Bartal, and X. Zhang, “Compressing surface plasmons for nano-scale optical focusing,” Opt. Express 17(9), 7519–7524 (2009). [PubMed]
8. D. A. Genov, M. Ambati, and X. Zhang, “Surface plasmon amplification in planar metal films,” IEEE J. Quantum Electron. 43(11), 1104–1108 (2007).
9. S. A. Maier, P. G. Kik, H. A. Atwater, S. Meltzer, E. Harel, B. E. Koel, and A. A. Requicha, “Local detection of electromagnetic energy transport below the diffraction limit in metal nanoparticle plasmon waveguides,” Nat. Mater. 2(4), 229–232 (2003). [PubMed]
10. S. I. Bozhevolnyi, V. S. Volkov, E. Devaux, and T. W. Ebbesen, “Channel plasmon-polariton guiding by subwavelength metal grooves,” Phys. Rev. Lett. 95(4), 046802 (2005). [PubMed]
11. D. F. Pile, T. Ogawa, D. K. Gramotnev, Y. Matsuzaki, K. C. Vernon, K. Yamaguchi, T. Okamoto, M. Haraguchi, and M. Fukui, “Two-dimensionally localized modes of a nanoscale gap plasmon waveguide,” Appl. Phys. Lett. 87(26), 261114 (2005).
12. R. F. Oulton, V. J. Sorger, D. Genov, D. Pile, and X. Zhang, “A hybrid plasmonic waveguide for subwavelength confinement and long-range propagation,” Nat. Photonics 2(8), 496–500 (2008).
13. R. F. Oulton, V. J. Sorger, T. Zentgraf, R.-M. Ma, C. Gladden, L. Dai, G. Bartal, and X. Zhang, “Plasmon lasers at deep subwavelength scale,” Nature 461(7264), 629–632 (2009). [PubMed]
14. H.-S. Chu, Y. Akimov, P. Bai, and E.-P. Li, “Submicrometer radius and highly confined plasmonic ring resonator filters based on hybrid metal-oxide-semiconductor waveguide,” Opt. Lett. 37(21), 4564–4566 (2012). [PubMed]
15. Y. Song, J. Wang, Q. Li, M. Yan, and M. Qiu, “Broadband coupler between silicon waveguide and hybrid plasmonic waveguide,” Opt. Express 18(12), 13173–13179 (2010). [PubMed]
16. Y. Bian and Q. Gong, “Low-loss light transport at the subwavelength scale in silicon nano-slot based symmetric hybrid plasmonic waveguiding schemes,” Opt. Express 21(20), 23907–23920 (2013). [PubMed]
17. H.-S. Chu, E.-P. Li, P. Bai, and R. Hegde, “Optical performance of single-mode hybrid dielectric-loaded plasmonic waveguide-based components,” Appl. Phys. Lett. 96(22), 221103 (2010).
18. S. Zhu, T. Y. Liow, G. Q. Lo, and D. L. Kwong, “Silicon-based horizontal nanoplasmonic slot waveguides for on-chip integration,” Opt. Express 19(9), 8888–8902 (2011). [PubMed]
19. M. Z. Alam, J. Meier, J. S. Aitchison, and M. Mojahedi, “Propagation characteristics of hybrid modes supported by metal-low-high index waveguides and bends,” Opt. Express 18(12), 12971–12979 (2010). [PubMed]
20. R. M. Ma, R. F. Oulton, V. J. Sorger, G. Bartal, and X. Zhang, “Room-temperature sub-diffraction-limited plasmon laser by total internal reflection,” Nat. Mater. 10(2), 110–113 (2011). [PubMed]
21. X. Guan, H. Wu, Y. Shi, L. Wosinski, and D. Dai, “Ultracompact and broadband polarization beam splitter utilizing the evanescent coupling between a hybrid plasmonic waveguide and a silicon nanowire,” Opt. Lett. 38(16), 3005–3008 (2013). [PubMed]
22. F. Lou, D. Dai, and L. Wosinski, “Ultracompact polarization beam splitter based on a dielectric-hybrid plasmonic-dielectric coupler,” Opt. Lett. 37(16), 3372–3374 (2012). [PubMed]
23. Y. A. Akimov and H. S. Chu, “Plasmon-plasmon interaction: controlling light at nanoscale,” Nanotechnology 23(44), 444004 (2012). [PubMed]
24. J. Tian, Z. Ma, Q. Li, Y. Song, Z. Liu, Q. Yang, C. Zha, J. Åkerman, L. Tong, and M. Qiu, “Nanowaveguides and couplers based on hybrid plasmonic modes,” Appl. Phys. Lett. 97(23), 231121 (2010).
25. R. Wan, F. Liu, and Y. Huang, “Ultrathin layer sensing based on hybrid coupler with short-range surface plasmon polariton and dielectric waveguide,” Opt. Lett. 35(2), 244–246 (2010). [PubMed]
26. F. Lou, Z. Wang, D. Dai, L. Thylen, and L. Wosinski, “Experimental demonstration of ultra-compact directional couplers based on silicon hybrid plasmonic waveguides,” Appl. Phys. Lett. 100(24), 241105 (2012).
27. S. Zhu, G. Lo, and D. Kwong, “Experimental demonstration of horizontal nanoplasmonic slot waveguide-ring resonators with submicrometer radius,” IEEE Photonics Technol. Lett. 23(24), 1896–1898 (2011).
28. D. Dai and S. He, “Low-loss hybrid plasmonic waveguide with double low-index nano-slots,” Opt. Express 18(17), 17958–17966 (2010). [PubMed]
29. A. Shacham, K. Bergman, and L. P. Carloni, “Photonic networks-on-chip for future generations of chip multiprocessors,” IEEE Trans. Comput. 57(9), 1246–1260 (2008).
30. M. Haurylau, G. Chen, H. Chen, J. Zhang, N. A. Nelson, D. H. Albonesi, E. G. Friedman, and P. M. Fauchet, “On-chip optical interconnect roadmap: Challenges and critical directions,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1699–1705 (2006).
31. J. W. Goodman, F. J. Leonberger, S.-Y. Kung, and R. A. Athale, “Optical interconnections for VLSI systems,” Proc. IEEE 72(7), 850–866 (1984).
32. D. A. Miller, “Optical interconnects to silicon,” IEEE J. Sel. Top. Quantum Electron. 6(6), 1312–1317 (2000).
33. B. G. Lee, X. Chen, A. Biberman, X. Liu, I. W. Hsieh, C. Y. Chou, J. I. Dadap, F. Xia, W. M. J. Green, L. Sekaric, Y. A. Vlasov, R. M. Osgood, and K. Bergman, “Ultrahigh-Bandwidth Silicon Photonic Nanowire Waveguides for On-Chip Networks,” IEEE Photonics Technol. Lett. 20(6), 398–400 (2008).
34. J. D. Bradley, M. Costa e Silva, M. Gay, L. Bramerie, A. Driessen, K. Wörhoff, J. C. Simon, and M. Pollnau, “170 Gbit/s transmission in an erbium-doped waveguide amplifier on silicon,” Opt. Express 17(24), 22201–22208 (2009). [PubMed]
35. L. Xu, W. Zhang, Q. Li, J. Chan, H. L. Lira, M. Lipson, and K. Bergman, “40-Gb/s DPSK data transmission through a silicon microring switch,” IEEE Photonics Technol. Lett. 24(5), 473 (2012).
36. J. Du, C. Gui, C. Li, Q. Yang, and J. Wang, “Design and fabrication of hybrid SPP waveguides for ultrahigh-bandwidth low-penalty 1.8-Tbit/s data transmission (161 WDM 11.2-Gbit/s OFDM 16-QAM),” in Lasers and Electro-Optics (CLEO),2014Conference on, (IEEE, 2014), 1–2.
37. G. Chen, H. Chen, M. Haurylau, N. A. Nelson, D. H. Albonesi, P. M. Fauchet, and E. G. Friedman, “Predictions of CMOS compatible on-chip optical interconnect,” Integration 40(4), 434–446 (2007).
38. A. D. Rakić, A. B. Djurišić, J. M. Elazar, and M. L. Majewski, “Optical properties of metallic films for vertical-cavity optoelectronic devices,” Appl. Opt. 37(22), 5271–5283 (1998). [PubMed]
39. C. Gui, C. Li, Q. Yang, and J. Wang, “Demonstration of terabit-scale data transmission in silicon vertical slot waveguides,” Opt. Express 23(8), 9736–9745 (2015). [PubMed]
40. C. Gui, C. Li, Q. Yang, and J. Wang, “Experimental demonstration of silicon vertical slot waveguides for ultra-wide bandwidth 1.8-Tbit/s (161 WDM 11.2-Gbit/s OFDM 16-QAM) data transmission,” in Optical Fibre Technology, 2014 OptoElectronics and Communication Conference and Australian Conference on, (IEEE, 2014), 514–516.