Mode multiplexers with tapers based on shortcuts to adiabaticity

Broadband, low-loss and low-crosstalk silicon mode (de)multiplexers with optimized tapers based on shortcuts to adiabaticity (STA) are proposed and experimentally demonstrated. The measured insertion losses and crosstalks are less than 1.1 dB and −24 dB, respectively, for the five two-mode mode-division-multiplexing (MDM) links over wavelengths ranging from 1500 nm to 1600 nm. The four-mode MDM link showed measured insertion losses and crosstalks less than 1.3 dB and −23 dB, respectively, within the same wavelength range. The method paves the way for future adaptation of the STA protocols to various components.