On-chip reconfigurable mode converter based on cross-connected subwavelength Y-junctions
A novel power-efficient reconfigurable mode converter is proposed and experimentally demonstrated based on cross-connected symmetric Y-junctions assisted by thermo-optic phase shifters on a silicon-on-insulator platform. Instead of using conventional Y-junctions, subwavelength symmetric Y-junctions are utilized to enhance the mode splitting ability. The reconfigurable functionality can be realized by controlling the induced phase differences. Benefited from the cross-connected scheme, the number of heating electrodes can be effectively reduced, while the performance of the device is maintained. With only one-step etching, our fabricated device shows the average insertion losses and cross talks are less than 2.45 and
基金项目：National Natural Science Foundation of China
Deming Liu：School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
Max Yan：Department of Applied Physics, KTH Royal Institute of Technology, Stockholm 11419, Sweden
Minming Zhang：School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China；Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China
备注：National Natural Science Foundation of China
【1】A. Shacham, K. Bergman and L. P. Carloni. Photonic networks-on-chip for future generations of chip multiprocessors. IEEE Trans. Comput. 57, 1246-1260(2008).
【2】D. A. B. MillerD. A. B. Miller. Device requirements for optical interconnects to silicon chips. Proc. IEEE. 97, 1166-1185(2009).
【3】W. Shipeng, F. Xianglian, G. Shiming, S. Yaocheng, D. Tingge and Y. Hui. On-chip reconfigurable optical add-drop multiplexer for hybrid wavelength/mode-division-multiplexing systems. Opt. Lett. 42, 2802-2805(2017).
【4】J. Wang, S. He and D. Dai. On-chip silicon 8-channel hybrid (de)multiplexer enabling simultaneous mode- and polarization-division-multiplexing. Laser Photonics Rev. 8, L18-L22(2014).
【5】L. W. Luo, N. Ophir, C. P. Chen, L. H. Gabrielli, C. B. Poitras, K. Bergmen and M. Lipson. WDM-compatible mode-division multiplexing on a silicon chip. Nat. Commun. 5, (2014).
【6】D. Dai and J. E. Bowers. Silicon-based on-chip multiplexing technologies and devices for peta-bit optical interconnects. Nanophotonics. 3, 283-311(2014).
【7】W. Chang, L. Lu, X. Ren, D. Li, Z. Pan, M. Cheng, D. Liu and M. Zhang. Ultra-compact mode (de)multiplexer based on subwavelength asymmetric Y-junction. Opt. Express. 26, 8162-8170(2018).
【8】D. DaiD. Dai. Silicon nanophotonic integrated devices for on-chip multiplexing and switching. J. Lightwave Technol. 35, 572-587(2017).
【9】L. Yang, T. Zhou, H. Jia, S. Yang, J. Ding, X. Fu and L. Zhang. General architectures for on-chip optical space and mode switching. Optica. 5, 180-187(2018).
【10】D. Dai, J. Wang and Y. Shi. Silicon mode (de)multiplexer enabling high capacity photonic networks-on-chip with a single-wavelength-carrier light. Opt. Lett. 38, 1422-1424(2013).
【11】Y. Ding, J. Xu, F. Da Ros, B. Huang, H. Ou and C. Peucheret. On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer. Opt. Express. 21, 10376-10382(2013).
【12】W. Chen, P. Wang and J. Yang. Mode multi/demultiplexer based on cascaded asymmetric Y-junctions. Opt. Express. 21, 25113-25119(2013).
【13】D. Dai, Y. Tang and J. E. Bowers. Mode conversion in tapered submicron silicon ridge optical waveguides. Opt. Express. 20, 13425-13439(2012).
【14】L. H. Frandsen, Y. Elesin, L. F. Frellsen, M. Mitrovic, Y. Ding, O. Sigmund and K. Yvind. Topology optimized mode conversion in a photonic crystal waveguide fabricated in silicon-on-insulator material. Opt. Express. 22, 8525-8532(2014).
【15】H. Jia, T. Zhou, X. Fu, J. Ding and L. Yang. Inverse-design and demonstration of ultracompact silicon meta-structure mode exchange device. ACS Photonics. 5, 1833-1838(2018).
【16】Q. Zhang, Y. Zhang, J. Li, R. Soref, T. Gu and J. Hu. Broadband nonvolatile photonic switching based on optical phase change materials: beyond the classical figure-of-merit. Opt. Lett. 43, 94-97(2018).
【17】H. Chen, H. Jia, J. Yang, Y. Tian and T. Wang. Ultra-compact switchable mode converter based on silicon and optical phase change material hybrid metastructure. Opt. Commun. 473, (2020).
【18】X. Han, Z. Zhang, J. Yang, H. Xiao and Y. Tian. On-chip switchable and reconfigurable optical mode exchange device using cascaded three-waveguide-coupling switches. Opt. Express. 28, 9552-9562(2020).
【19】C. Sun, Y. Yu, G. Chen and X. Zhang. Integrated switchable mode exchange for reconfigurable mode-multiplexing optical networks. Opt. Lett. 41, 3257-3260(2016).
【20】Q. Huang, W. Jin and K. S. Chiang. Broadband mode switch based on a three-dimensional waveguide Mach-Zehnder interferometer. Opt. Lett. 42, 4877-4880(2017).
【21】L. B. Soldano and E. C. M. Pennings. Optical multi-mode interference devices based on self-imaging: principles and applications. J. Lightwave Technol. 13, 615-627(1995).
【22】R. Liu, L. Lu, P. Zhang, W. Chang and M. Zhang. Integrated dual-mode 3 dB power splitter based on multimode interference coupler. IEEE Photonics Technol. Lett. 32, 883-886(2020).
【23】N. Riesen, S. Gross, J. Love and M. J. Withford. Femtosecond direct-written integrated mode couplers. Opt. Express. 22, 29855-29861(2014).
【24】J. Dong, K. S. Chiang and W. Jin. Mode multiplexer based on integrated horizontal and vertical polymer waveguide couplers. Opt. Lett. 40, 3125-3128(2015).
【25】C. Sun, Y. Yu and X. Zhang. Ultra-compact waveguide crossing for a mode-division multiplexing optical network. Opt. Lett. 42, 4913-4916(2017).
【26】L. Lu, D. Liu, M. Yan and M. Zhang. Subwavelength adiabatic multimode Y-junctions. Opt. Lett. 44, 4729-4732(2019).
【27】T. Uematsu, Y. Ishizaka, Y. Kawaguchi, K. Saitoh and M. Koshiba. Design of a compact two-mode multi/demultiplexer consisting of multimode interference waveguides and a wavelength-insensitive phase shifter for mode-division multiplexing transmission. J. Lightwave Technol. 30, 2421-2426(2012).
【28】G. T. Reed, G. Mashanovich, F. Y. Gardes and D. J. Thomson. Silicon optical modulators. Nat. Photonics. 4, 518-526(2010).
【29】V. Sorianello, M. Midrio, G. Contestabile, I. Asselberghs, J. Van Campenhout, C. Huyghebaert, I. Goykhman, A. K. Ott, A. C. Ferrari and M. Romagnoli. Graphene-silicon phase modulators with gigahertz bandwidth. Nat. Photonics. 12, 40-44(2018).
Longhui Lu, Deming Liu, Max Yan, and Minming Zhang, "On-chip reconfigurable mode converter based on cross-connected subwavelength Y-junctions," Photonics Research 9(1), 43-48 (2021)