Non-Contact with Photochromism Strong-Coupling Modulation for a Miniaturized Computational Spectrometer

Abstract Miniaturized computational spectrometers capable of high-resolution spectral measurement are increasingly in demand for on-chip and portable systems. Dynamic modulation can improve spectral resolution by increasing the number and diversity of spectral responses without enlarging the filter footprint. However, existing electrical and thermal modulation schemes often require complex electrode structures and multistep fabrication processes, increasing device complexity and limiting integration. Developing a non-contact modulation strategy that simplifies device architecture and eliminates complex electrodes is therefore key to realizing lightweight, highly integrated spectrometers. Here, we exploit strong coupling between photochromic molecules and a Fabry–Pérot cavity mode to achieve non-contact dynamic modulate of the filter’s transmission spectrum, enriching the spectral sampling information and thereby improving the resolution of spectral reconstruction. With optical modulation, the proposed spectrometer reduces the mean FWHM reconstruction error from 0.50 nm to 0.27 nm and resolves spectral features with an FWHM of 3 nm across 400–700 nm. More importantly, we verified the filter’s spatially selective modulation capability. By independently tuning the strong-coupling response in different filter unit through localized illumination, diverse spectral response channels can be dynamically constructed. Even with only four filter units, the system enables spectral reconstruction with good resolution. This non-contact dynamic modulation strategy requires neither structural modification nor complex electrical driving and supports spatially selective control for on-demand spectral channel configuration, enabling compact, low-cost, and reconfigurable spectrometers for on-chip integration, portable sensing, and spectral analysis across diverse applications.