Compact polymeric four-wavelength multiplexers based on cascaded step-size MMI for 1G/10G hybrid TDM-PON applications.

A novel polymeric four-wavelength multiplexer based on a new design concept of cascaded step-size multimode interferometer (CSS-MMI) is first presented. It can be fabricated by using planar lightwave circuit (PLC) technology and is highly compatible with both current 1-Gbps and future 10Gbps optical transceivers for applications in next generation 1-Gbps and 10-Gbps coexisting time-division-multiplexed passive optical network (TDM PON). By combining two types of proposed CSS-MMI 1??2 wavelength splitters, a compact 1.5cm-long four wavelength multiplexer is realized without requiring complicated design and tedious calculation. In addition, the upstream wavelength channel at 1310 nm has 0.18 dB low insertion loss and three downstream wavelength channels at 1490 nm, 1550 nm and 1590 nm exhibit insertion losses of 1.21 dB, 1.34 dB and 1.02 dB, respectively, with their extinction ratios ranging from 11.71 dB to 32.07 dB.