Ultracompact 40-Channel Arrayed Waveguide Grating on Silicon Nitride Platform at 860 nm

Arrayed waveguide gratings (AWG) have been widely used as wavelength multiplexers and demultiplexers in dense wavelength division multiplexing communications. In this letter, we describe a highly compact 40-channel AWG fabricated on the silicon nitride platform for operation with a center wavelength near 860 nm for use in spectral domain optical coherence tomography. The total footprint of the AWG is 910μm × 680μm. The transmission spectrum of the fabricated device was measured. The AWG had a channel spacing of 1.5 nm and optical spectral range of 60 nm, in accord with the design. The measured insertion loss was 1.3 dB for the central channels and 1.8 dB for the outmost channels. The inter-channel crosstalk varied from 17.2 dB to 19.7 dB for the central 20 channels.