Mode Division Multiplexing Based on Supermodes in Densely Packed Uniform Waveguide Array (DPUWA)

Abstract

A multimode bus structure consisting of densely packed uniform waveguide array (DPUWA) with a narrow gap of 150 nm is proposed. A compact and robust mode converter between DPUWA and a conventional wide multimode waveguide is designed with an insertion loss of <0.05 dB and crosstalk of <−20 dB in a wide wavelength range for three TE and three TM modes. Supermodes in the DPUWA can be routed and processed just like the mode in a single-mode waveguide by simply expanding the gap without any mode (de)multiplexer. Based on such ideas, compact DPUWA crossing/bending structures with losses of <0.2/0.09 dB and crosstalks of <−34/−30 dB for three TE modes are achieved.

Silicon Mode (de)Multiplexer Based on Cascaded Particle-Swarm-Optimized Counter-Tapered Couplers

“…For realizing a densely integrated MDM system, mode (de)multiplexers are one of the key functional components. Up to now, various approaches have been developed to experimentally demonstrate mode (de)multiplexers on the silicon-on-insulator (SOI) platform, such as grating assisted couplers (GACs) [6], [7], adiabatic couplers (ACs) [8][9][10][11][12], densely packed multimode waveguide arrays (DPMWAs) [13], [14], inverse design [15][16][17], asymmetric directional couplers (ADCs) [18][19][20][21], asymmetric Y-junctions [22][23][24], and tapered directional couplers (TDCs) [25], [26]. Although the fabricated GAC-based mode (de)multiplexers can realize low crosstalk, their bandwidths are limited.…”