Resolution-Switchable Silicon-Based On-Chip Spectrometer

We demonstrate the first resolution-switchable on-chip silicon photonic spectrometer achieved through the integration of multimode waveguide gratings (MWGs) and thermally tunable photonic crystal nanobeam cavities (PCNCs). Leveraging a cascaded wide-bandpass MWG, the target spectrum is partitioned into multiple independent sub-bands, enabling a broad operational bandwidth and customizable spectral ranges as required. The PCNCs provide precise filtering for each sub-band and facilitate resolution switching to balance spectral resolution and detection speed efficiently. In this work, a 10-channel spectrometer with switchable resolution is demonstrated, which is fabricated using a standard Multi-Project Wafer (MPW) foundry process with a compact footprint of 0.36 mm². Operating over a spectral range of 1480–1567 nm, the spectrometer offers a high-resolution mode of 0.04 nm for enhanced precision and a low-resolution mode of 0.12 nm for accelerated detection. The effectiveness of this design is further validated through the spectral analysis of Hydrogen Cyanide gas under varying resolutions. This innovative architecture marks a significant advancement in adaptive spectral measurement, showcasing immense potential for diverse applications, including large-scale gas monitoring, multisample pharmaceutical analysis, and other precision-demanding fields.