A compact and low loss 90° optical hybrid on a silicon-on-insulator platform

We present a compact and low loss 90° optical hybrid on a silicon-on-insulator (SOI) platform for coherent receiving systems. Our 90° optical hybrid uses a novel topology, comprising one Y-junction and three 2x2 multimode interference (MMI) couplers. The geometry of the 90° optical hybrid is fully optimized using particle swarm optimization (PSO). The fabricated 90° optical hybrid has a compact footprint of 21.6 μm x 27.9 μm, with an insertion loss less than 0.5 dB, a common mode rejection ratio (CMRR) larger than 30 dB, and phase error smaller than 3° in the C-band across 22 reticles on one wafer. The measured phase error (< 3°) in a packaged coherent receiver further confirms the excellent performance of the 90° optical hybrid. © 2017 Optical Society of America OCIS codes: (060.1660) Coherent communications; (230.3120) Integrated optics devices; (230.7370) Waveguides. References and links 1. R. W. Tkach, “Scaling optical communications for the next decade and beyond,” Bell Labs Tech. J. 14(4), 3–9 (2010). 2. M. Nakazawa, K. Kikuchi, and T. Miyazaki, High Spectral Density Optical Communication Technologies (Springer, 2010). 3. P. Dong, X. Liu, S. Chandrasekhar, L. Buhl, R. Aroca, and Y.-K. Chen, “Monolithic silicon photonic integrated circuits for compact 100+ Gb/s coherent optical receivers and transmitters,” IEEE J. Sel. Top. Quantum Electron. 20(4), 150–157 (2014). 4. K. Kikuchi, “Fundamentals of coherent optical fiber communications,” J. Lightwave Technol. 34(1), 157–179 (2016). 5. C. Lam, H. Liu, B. Koley, X. Zhao, V. Kamalov, and V. Gill, “Fiber optic communication technologies: what’s needed for datacenter network operations,” IEEE Commun. Mag. 48(7), 32–39 (2010). 6. H. Rohde, E. Gottwald, A. Teixeira, J. D. Reis, A. Shahpari, K. Pulverer, and J. S. Wey, “Coherent ultra dense WDM technology for next generation optical metro and access networks,” J. Lightwave Technol. 32(10), 2041– 2052 (2014). 7. E. Agrell, M. Karlsson, A. R. Chraplyvy, D. J. Rochardson, P. M. Krummrich, P. Winzer, K. Roberts, J. K. Fisher, S. J. Savory, B. J. Eggleton, M. Secondini, F. R. Kschischang, A. Lord, J. Prat, I. Tomkos, J. E. Bowers, S. Srinivasan, M. B. Pearce, and N. Gisin, “Roadmap of optical communications,” J. Opt. 18(6), 063002 (2016). 8. N. Nguyen, P. J. Skahan, J. M. Garcia, E. Lively, H. N. Poulsen, D. M. Baney, and D. J. Blumenthal, “Monolithically integrated dual-quadrature receiver on InP with 30 nm tunable local oscillator,” Opt. Express 19(26), B716–B721 (2011). 9. Y. Sakamaki, H. Yamazaki, T. Mizuno, T. Goh, Y. Nasu, T. Hashimoto, S. Kamei, K. Hattori, and H. Takahashi. "One-chip integrated dual polarization optical hybrid using silica-based planar lightwave circuit technology." in European Conference and Exhibition on Optical Communication (IEEE, 2009), pp. 1-2. 10. F. Gambini, G. Meloni, S. Faralli, G. Contestabile, L. Potì, and J. Klamkin, “Ultra-compact 56-Gb/s QPSK and 80-Gb/s 16-QAM silicon coherent receiver free of waveguide crossings,” in Proceedings of IEEE Conference on Group IV Photonics (IEEE, 2014), pp. 149–150. 11. S. Faralli, G. Meloni, F. Gambini, J. Klamkin, L. Potì, and G. Contestabile, “A compact silicon coherent receiver without waveguide crossing,” IEEE Photonics J. 7(4), 1-6 (2015). 12. K. Voigt, L. Zimmermann, G. Winzer, H. Tian, B. Tillack, and K. Petermann, “C-band optical 90° hybrids in silicon nanowaveguide technology,” IEEE Photonics Technol. Lett. 23(23), 1769–1771 (2011). 13. P. Runge, S. Schubert, A. Seeger, K. Janiak, J. Stephan, D. Trommer, P. Domburg, and M. Nielsen, "Monolithic InP receiver chip with a 90° hybrid and 56 GHz balanced photodiodes," Opt. Express 20(26), B250-B255 (2012). 14. S.-H. Jeong and K. Morito, “Novel optical 90° hybrid consisting of a paired interference based 2×4 MMI coupler, a phase shifter and a 2×2 MMI Coupler,” J. Lightwave Technol. 28(9), 1323–1331 (2010). 15. W. Yang, M. Yin, Y. Li, X. Wang, and Z. Wang, “Ultra-compact optical 90° hybrid based on a wedge-shaped 2 × 4 MMI coupler and a 2 × 2 MMI coupler in silicon-on-insulator,” Opt. Express 21(23), 28423–28431 (2013). 16. H. Yagi, N. Inoue, R. Masuyama, T. Kikuchi, T. Katsuyama, Y. Tateiwa, K. Uesaka, Y. Yoneda, M. Takechi, and H. Shoji, “InP-Based pin-Photodiode Array Integrated With 90o Hybrid Using Butt-Joint Regrowth for Compact 100 Gb/s Coherent Receiver,” IEEE J. Sel. Top. Quantum Electron. 20(6), 374–380 (2014). 17. Y. Sakamaki, T. Kawai, T. Komukai, M. Fukutoku, T. Kataoka, T. Watanabe, and Y. Ishii, “Experimental demonstration of multi-degree colorless, directionless, contentionless ROADM for 127-Gbit/s PDM-QPSK transmission system,” Opt. Express 19(26), B1–B11 (2011). 18. D. Hoffman, H. Heidrich, G. Wenke, R. Langenhorst, and E. Dietrich, “Integrated optics eight-port 90° hybrid on LiNbO3,” J. Lightwave Technol. 7(5), 794–798 (1989). 19. M. Seimetz and C. M. Weinert, “Options, feasibility and availability of 2×4 90° hybrids for coherent optical systems,” J. Lightwave Technol. 24(3), 1317–1322 (2006). 20. S. Jeong and K. Morito, “Simple analytical calculation and experimental demonstration of optical 90° hybrids based on tapered 2×4 and 2×2 multimode interference couplers,” J. Opt. Soc. Am. B 28(1), 159-164 (2011). 21. R. Halir, G. Roelkens, A. Ortega-Moñux, and J. G. Wangüemert-Pérez, “High-performance 90° hybrid based on a silicon-on-insulator multimode interference coupler,” Opt. Lett. 36(2), 178–180 (2011). 22. M. Bachmann, P. Besse, and H. Melchior, “General self-imaging properties in NxN multimode interference couplers including phase relations,” Appl. Opt. 33(18), 3905–3911 (1994). 23. L. B. Soldano, and C. M. Pennings, “Optical multi-mode interference devices based on self-imaging: Principles and Applications,” J. Lightwave Technol. 13(4), 615–627 (1995). 24. M. R. Paiam and R. I. Macdonald, “Design of phased-array wavelength division multiplexers using multimode interference couplers,” Appl. Opt. 36(21), 5097–5108 (1997). 25. R. Adar, C. H. Henry, M. A. Milbrodt, and R. C. Kistler, “Phase coherence of optical waveguides,” J. Lightwave Technol. 12(4), 603–606 (1994). 26. Y. Yang, Y. Ma, H. Guan, Y. Liu, S. Danziger, S. Ocheltree, K. Bergman, T. Baehr-Jones, and M. Hochberg, “Phase coherence length in silicon photonic platform,” Opt. Express 23(13), 16890–16902 (2015). 27. L. Chrostowski, X. Wang, J. Flueckiger, Y. Wu, Y. Wang, and S. T. Fard, “Impact of fabrication nonuniformity on chip-scale silicon photonic integrated circuits,” in Optical Fiber Communication Conference (OSA, 2014), paper Th2A–37. 28. Y. Zhang, S. Yang, A. E.-J. Lim, G.-Q. Lo, C. Galland, T. Baehr-Jones, and M. Hochberg, “A compact and low loss Y-junction for submicron silicon waveguide,” Opt. Express 21(1), 1310–1316 (2013). 29. Y. Ma, Y. Zhang, S. Yang, A. Novack, R. Ding, A. E.-J. Lim, G.-Q. Lo, T. Baehr-Jones, and M. Hochberg, “Ultralow loss single layer submicron silicon waveguide crossing for SOI optical interconnect,” Opt. Express 21(24), 29374–29382 (2013). 30. H. Guan, Y. Ma, R. Shi, A. Novack, J. Tao, Q. Fang, A. E.-J. Lim, G.-Q. Lo, T. Baehr-Jones, and M. Hochberg, “Ultracompact silicon-on-insulator polarization rotator for polarization-diversified circuits,” Opt. Lett. 39(16), 4703–4706 (2014). 31. Y. Vlasov and S. McNab, “Losses in single-mode silicon-on-insulator strip waveguides and bends,” Opt. Express 12(8), 1622–1631 (2004). 32. W. Bogaerts and S. K. Selvaraja, “Compact single-mode silicon hybrid rib/strip waveguide with adiabatic bends,” IEEE Photonics J. 3(3), 422–432 (2011). 33. T. Fujisawa, S. Makino, T. Sato, and K. Saitoh, "Low-loss, compact, and fabrication-tolerant Si-wire 90° waveguide bend using clothoid and normal curves for large scale photonic integrated circuits," Opt. Express 25(8), 9150-9159 (2017). 34. A. Novack, Y. Liu, R. Ding, M. Gould, T. Baehr-Jones, Q. Li, Y. Yang, Y. Ma, Y. Zhang, K. Padmaraju, K. Bergman, A. E.-J. Lim, G.-Q. Lo, and M. Hochberg, “A 30 GHz silicon photonic platform,” in Proceedings of IEEE Conference on Group IV Photonics (IEEE, 2013), pp. 7–8. 35. “Implementation Agreement for CFP2-Analogue Coherent Optics Module,” OIF.2014.75.13, Working Group: PLL, October 2013.