Flat-Top Eight-Channel Wavelength Division Demultiplexer for L-Band Optical Communication With Low Crosstalk

We have demonstrated an eight-channel wavelength demultiplexer in the L-band based on a cascaded Mach-Zehnder interferometer (MZI) lattice filter fabricated on an 8-inch silicon nitride (SiN) photonics platform. A flat passband is achieved, and channel crosstalk is minimized through a cascaded three-stage MZI structure. The demultiplexing of eight targeted wavelengths within the range of 1580 nm to 1600 nm is successfully accomplished without requiring a thermo-optic phase shifter. For the best-performing device, the experimentally measured device insertion loss is less than 1.8 dB, the channel crosstalk is less than -18 dB, and the 1-dB bandwidth reaches 1.8 nm. On an 8-inch wafer, the average insertion loss and the worst crosstalk of the device are 1.8 dB and −14.8 dB, respectively. The demonstrated passive eight-channel demultiplexer provides a reliable solution for the L-band optical data communication.