Experimental demonstration of an optical quantizer with ENOB of 3.31 bit by using a cascaded step-size MMI

We experimentally demonstrated an optical phase shifted quantizer using a cascade step-size MMI (CS-MMI), which was fabricated on a commercially available 220-nm SOI platform via multi-project wafer (MPW) process. An experimental setup was built to test the ability of the CS-MMI acting as a quantizer. The experimental results show that the proposed CS-MMI-based quantizer has an effective number of bit (ENOB) of 3.31bit, which is a little slighter than the ideal ENOB of 3.32bit. The operation range is 12 nm for ENOB≥3 bit. Moreover, the insertion loss of the CS-MMI is -1.26 dB at 1560 nm, the performance of the fabricated device agrees well with simulation results.