Compact, Broadband Waveguide Two-Mode (De)-Multiplexers based on Rapid Adiabatic Coupling

The concept of rapid adiabaticity is applied to design a mode evolution based two-spatial-mode mux-demux chain, shorter than conventional adiabatic devices by a factor of 4. The 100-µm-long device measures <-26 dB cross-talk over 80 nm bandwidth and IL <0.2dB at 1550 nm.