Microscale Photoelasticity Engineering in PETG Polymer for Spectroscopic Applications

ABSTRACT Miniaturization of spectral response components is pivotal for achieving high integrability of computationally augmented spectroscopic systems. However, as the physical size of such components shrinks, their response bandwidth tends to narrow progressively. This trade‐off necessitates the integration of numerous structurally differentiated response units to compensate for the reduced sampling number. Here, we introduce a straightforward photoelasticity‐engineered spectral response strategy to address this challenge. This design employs ultrafast laser‐induced micro‐vortex structures in polyethylene terephthalate glycol (PETG) to achieve high‐efficiency spatiotemporal encoding through their frequency‐dependent stress birefringence. A single encoding unit can operate across the wavelength range from 400 to 1550 nm with compact physical dimensions, with its spectral characteristics being adjusted via polarization, delivering rich, pixel‐wise tunable spectral responses for reconstructive spectroscopy. We demonstrate the potential of this structure in linear‐polarization‐orientation analysis, spectral imaging, and dual‐modal biometric authentication applications. This method opens the possibility for efficient spectral encoding within thermoplastic media, paving the way for versatile and cost‐efficient integrated spectroscopic systems.