Miniaturized computational spectrometer enabled by the photoelastic effect with adaptive modulation units selection

Miniature computational spectrometers, distinguished by their compact size and light weight, have shown great promise for on-chip and portable applications in the fields of healthcare, environmental monitoring, food safety, and industrial process monitoring. However, the common miniaturization strategies predominantly rely on advanced micronano fabrication and complex material engineering, limiting their scalability and affordability. Here, we present a broadband miniaturized computational spectrometer (ElastoSpec) enabled by the photoelastic effect, featuring easy-to-prepare and configurable implementation with adaptive modulation units selection for optimized spectral reconstruction. A single computational photoelastic spectral filter, with only two polarizers and a plastic sheet, is designed to be integrated onto the top of a CMOS sensor for snapshot spectral acquisition. The distinct spectral modulation units are directly generated from different spatial locations of the filter, due to the photoelastic-induced chromatic polarization effect of the plastic sheet. We experimentally demonstrate that ElastoSpec offers excellent reconstruction accuracy for the measurement of both simple narrowband and complex spectra. ElastoSpec exhibits a spectral resolution of 2 nm and achieves a full width at half maximum (FWHM) error of approximately 0.2 nm for monochromatic inputs. It also maintains a mean squared error (MSE) value on the order of 10⁻³ with only 10 spectral modulation units. Furthermore, we develop an adaptive strategy for selecting modulation units to enhance spectrum sensing performance through the flexibility in optimizing the modulation effectiveness and the number of spectral modulation units. This work avoids the need for complex micro-nano fabrication and specialized materials for the design of computational spectrometers, thus paving the way for the development of simple, cost-effective, and scalable solutions for on-chip and portable spectral sensing devices.