Novel High‐Resolution and Large‐Bandwidth Micro‐Spectrometer Using Multi‐Input Counter‐Propagating Arrayed Waveguide Grating and Dual‐Wavelength Grating Coupler on Silicon on Insulator

Abstract Miniaturized micro‐spectrometers with high‐resolution and large‐bandwidth are of great importance for on‐site spectroscopic analysis applications. Here, a novel high‐resolution and large‐bandwidth micro‐spectrometer is presented, which operates at dual‐wavelength band by utilizing a ( N + 3) × ( N + 3) arrayed waveguide grating (AWG) and three dual‐wavelength grating couplers on a silicon‐on‐insulator (SOI) platform. The AWG working in a counter‐propagating manner can be viewed as two 3 × N AWGs, and the dual‐wavelength grating coupler acts as a prefilter. Three time‐division‐multiplexing inputs with wavelength spacings of 4/3 times that of N output waveguides are employed to improve the resolution of the micro‐spectrometer. Combining the corresponding outputs of three inputs, a micro‐spectrometer with resolution enhanced to one‐third wavelength spacing of output waveguides and effective channel number enlarged to 3 × ( N − 2) is achieved, only using N output channels at each wavelength band. A micro‐spectrometer with 63 effective channels and resolutions of 0.5 and 0.442 nm at 1550 and 1310 nm bands, respectively, is experimentally demonstrated. The footprint of the fabricated micro‐spectrometer is 2 × 0.81 mm 2 , with measured on‐chip losses of −4.6 to −2.8 dB (−7.0 to −3.1 dB) and crosstalk levels < −18.5 (−16.8) dB at the 1550 (1310) nm band.