A Polarization Multiplexing Optical Circuit for Efficient Phase Tuning

The high efficiency on-chip optical phase shifters are required in almost every photo-electronic integration systems. In this work, we present a novel silicon optical circuit for the efficient phase shifiting. A polarization multiplexing scheme is proposed to improve the effective phase tuning length. The circuit is fabricated and in depth analyzed, exhibiting a 3.57 times effective group optical length enhancement compared with the traditional design. Moreover, A thermal-tuning phase shift based on such polarization multiplexing structure was experimentally demonstrated. Within the size of $75 \times 320~\mu \text{m}^{2}$ , a 63.8% power saving for thermal phase shift was measured in the proposed circuit. With considerable efficiency, such circuit is expected to serve as a general underlying structure for the silicon based integrated phase tuning.