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

• Published in: Optics letters Vol. 46; no. 6; p. 1341
• Main Authors: Dinh, Thi Thuy Duong, González-Andrade, David, Montesinos-Ballester, Miguel, Deniel, Lucas, Szelag, Bertrand, Le Roux, Xavier, Cassan, Eric, Marris-Morini, Delphine, Vivien, Laurent, Cheben, Pavel, Velasco, Aitor V, Alonso-Ramos, Carlos
• Format: Journal Article
• Language: English
• Published: United States 15.03.2021
• ISSN: 1539-4794
• DOI: 10.1364/OL.418278

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 (étendue, 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 90µ ×60µ formed by a two-way-fed grating coupler. We experimentally demonstrate 85 pm spectral resolution, 600 pm bandwidth, and 13 dB étendue 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 4.5 footprint.