The 9th International Conference on Surface Engineering (ICSE 2024)

There is a significant demand for miniaturized on-chip spectrometers that are compact, lightweight, and cost-effective, for applications such as portable optical sensing and lab-on-chip systems. Typically, these miniaturized spectrometers are based on engineered spectral response units and employ algorithms to reconstruct unknown spectra. However, the limited size of computational on-chip spectrometers restricts the recovered spectral resolution, which is limited by the number of integrated spectral response units/filters. Therefore, it is a challenge to enhance the spectral resolution without increasing the number of utilized filters. In this talk, we introduce a computational on-chip spectrometer that utilizes electrochromic filter-based computational spectral units, which can be electrochemically modulated to increase the effective sampling number for higher spectral resolution. These filters are directly integrated onto the photodetector pixels, and the spectral modulation of the filters is a result of redox reactions during the dual injection of ions and electrons into the electrochromic material. We experimentally show that the spectral resolution of the proposed spectrometer can be effectively improved as the number of applied voltages increases. The average difference between the peak wavelengths of the reconstructed and reference spectra decreases from 14.48 nm to 2.57 nm. We also demonstrate that the proposed spectrometer can operate with only four or two filter units, with the assistance of electrochromic modulation. Additionally, we show that the electrochromic filter is readily adaptable for hyperspectral imaging due to its uniform transparency. This approach provides a new means to improve the performance of miniaturized spectrometers with tunable spectral filters for high-resolution, low-cost, and portable spectral sensing. It also inspires the exploration of other stimulus responses, such as photochromic and force-chromic, on computational spectrometers.

Electrochromic,spectrometer