An Inversely Designed Reconstructive Spectrometer on SiN Platform

Reconstructive spectrometers, which leverage the compressive sensing technique and computational algorithm, are promising solutions for high‐performance integrated spectrometers. Among the various options for realizing reconstructive spectrometers, stratified waveguide filters (SWFs) have emerged as a particularly attractive choice due to their ultra‐compact size and high performance. However, previous demonstrations of SWFs on silicon substrates have suffered from suboptimal and non‐reproducible spectrometer performance due to the brute‐force random design approach. In this paper, applying a bio‐inspired inverse design algorithm to the system level of multiple correlated SWFs is proposed. The algorithm allows for the precise and optimized design of the SWFs in order for higher spectral resolution of each SWF and lower spectral cross‐correlations between any two SWFs, overcoming the limitations of previous methods. The effectiveness of this approach is demonstrated by implementing a reconstructive spectrometer on a silicon nitride (SiN) platform, which is more thermally stable and can support a wider optical range than silicon.