Experimental demonstration of self-aligned InP/InGaAsP polarization converter for polarization multiplexed photonic integrated circuits

Highly efficient, low-loss, and compact InP/InGaAsP polarization converter based on a half-ridge waveguide structure is fabricated and demonstrated experimentally. The device is fabricated by a simple self-aligned process and integrated with a ridge InP waveguide. Using a 150-μm-long device, we obtain the mode conversion of more than 96% and the on-chip loss of less than 1.0 dB over the broad wavelength range from 1510 to 1575 nm. The experimental results are explained quantitatively using the full-vector eigenmode calculation, which also reveals large fabrication tolerance of the demonstrated device.