Silicon photonic on-chip spatial heterodyne Fourier transform spectrometer exploiting the Jacquinot's advantage

Silicon photonics on-chip spectrometers are finding important applications in medical diagnostics, pollution monitoring, and astrophysics. Spatial heterodyne Fourier transform spectrometers (SHFTSs) provide a particularly interesting architecture with a powerful passive error correction capability and high spectral resolution. Despite having an intrinsically large optical throughput (etendue, also referred to as Jacquinot's advantage), state-of-the-art silicon SHFTSs have not exploited this advantage yet. Here, we propose and experimentally demonstrate for the first time, to the best of our knowledge, an SHFTS implementing a wide-area light collection system simultaneously feeding an array of 16 interferometers, with an input aperture as large as 90 mu m x 60 mu m formedby a two-way-fed grating coupler. We experimentally demonstrate 85 pm spectral resolution, 600 pm bandwidth, and 13 dB etendue increase, compared with a device with a conventional grating coupler input. The SHFTS was fabricated using 193 nm deep-UV optical lithography and integrates a large-size input aperture with an interferometer array and monolithic Ge photodetectors, in a 4.5mm(2) footprint. (C) 2021 Optical Society of America

Automated summary

Silicon photonics on-chip spectrometers, particularly the spatial heterodyne Fourier transform spectrometers (SHFTSs), have shown potential in various fields such as medical diagnostics, pollution monitoring, and astrophysics. A recent advancement in this technology demonstrated an SHFTS with wide-area light collection and 16 interferometers, achieving high spectral resolution and increased etendue compared to conventional devices.