Silicon Nitride (Si3N4) (De-)Multiplexers for 1-μm CWDM Optical Interconnects

Abstract

We discuss the design and demonstration of 4-channel coarse wavelength-division (de-)multiplexers based on cascaded Mach-Zehnder interferometer (MZI) lattice filters and arrayed waveguide gratings (AWG) on a 150 nm silicon nitride (Si3N4) platform. The 1 × 4 (de-)multiplexers are designed for a channel separation of 25 nm and operate within 990-1065 nm for bottom emitting vertical cavity surface emitting lasers (VCSEL)-based optical links. For Si3N4 Gaussian AWGs, we demonstrate crosstalk <0.5 dB. Measurements were performed over many dies, and pass-band standard deviations for channel 1-4 are 0.49, 0.66, 0.42, and 0.37 nm, respectively. Results for flat-top AWGs indicate crosstalk <3 dB for the best devices. Flat-top cascaded 2nd order and 3rd order MZI lattice filters show a minimum of crosstalk