Ultra-small size arbitrary-port-input reflective arrayed waveguide grating based on a silicon-on-insulator platform

To address the challenge of a large footprint associated with conventional arrayed waveguide gratings (AWG), this study presents an ultra-compact 5-channel reflective AWG based on a silicon-on-insulator (SOI) platform. Unlike traditional AWGs, this design reduces the footprint of the device by reducing its components to just a set of input/output waveguides, a slab waveguide, array waveguides with halved length, and a ring-reflector array, effectively halving the device's physical footprint. Furthermore, to address the issue of spectral discontinuity in reflective AWGs, a systematic approach to optimizing the Free Spectral Range (FSR) is introduced, which permits the device to freely select any input waveguides as the signal input, leading to achieving continuous and uniform output spectra. Importantly, heterogeneous integration or the use of a different thickness etching process compared to the rest of the AWG is not necessary as the reflector section. It consists of just a 1 × 2 multimode interference coupler (MMI) and Bessel-bending waveguide, significantly simplifying the fabrication process. Measurement results demonstrate that the arbitrary-port-input reflective AWG can be prepared by a single etching step. Notably, the device exhibits a compact physical size, measuring only 0.5 mm × 0.14 mm. This designed reflective AWG holds significant promise for applications encompassing wavelength division multiplexing/demultiplexing, wavelength routing, and other functions, making it particularly valuable for high-throughput data transmission links.