Silicon photonic spectrometer with multiple customized wavelength bands

Abstract

A silicon photonic spectrometer with multiple customized wavelength bands is developed by introducing multiple channels of wideband optical filters based on multimode waveguide gratings (MWGs) for pre-filtering and the corresponding thermally tunable narrowband filter for high resolution. For these multiple customized wavelength bands, the central wavelengths, bandwidths, and resolutions are designed flexibly as desired, so that the system is simplified and the footprint is minimized for several practical applications (e.g., gas sensing). A customized silicon photonic spectrometer is designed and demonstrated experimentally with four wavelength bands centered around 1310 nm, 1560 nm, 1570 nm, and 1930 nm, which is, to the best of our knowledge, the first on-chip spectrometer available for sensing multiple gas components like HF, CO, H2S, and CO2. The spectral resolutions of the four wavelength bands are 0.11 nm, 0.08 nm, 0.08 nm, and 0.37 nm, respectively. Such a customized silicon photonic spectrometer shows great potential for various applications, including gas monitors, wearable biosensors, and portable spectral-domain optical coherence tomography.