A Polarization-Insensitive Dual-Wavelength Multiplexer Based on Bent Directional Couplers

An on-chip polarization-insensitive wavelength (de-)multiplexer based on cascaded bent directional couplers (DCs) is demonstrated. With the proper design of the bent DCs, the device can separate the two wavelength bands for TE and TM polarizations simultaneously. The characterization of the fabricated device shows slow polarization dependent loss and crosstalk less than 1 dB and -15 dB, respectively. The footprint of our polarization-insensitive dual-wavelength multiplexer is 40 x 25 mu m(2), which is the smallest among the reported (de) multiplexers in the silicon-on-insulator platform at the telecom wavelength range.