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

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) x (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 x 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 x (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 x 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.