Tunable hyperspectral filter based on rotated chirped volume Bragg gratings.

Abstract

Spectral filtering of the transverse profile of hyperspectral beams is essential in various areas of optics, from multimode photonics and hyperspectral imaging to optical communications. An optimal hyperspectral filter requires flexible tuning capabilities, both in central wavelength and spectral bandwidth. Currently available filters-such as thin-film, acousto-optic, and liquid crystal tunable filters (TFTFs, AOTFs, and LCTFs)-exhibit limitations such as restricted tuning ranges, compromised image quality, or relatively low damage thresholds. Here, we propose and demonstrate a novel, to our knowledge, tunable hyperspectral filter based on rotated chirped volume Bragg gratings. Our filter enables continuous and independent tuning of the central wavelength and full-width at half-maximum (FWHM) bandwidth, steep spectral edges, and high out-of-band rejection. Furthermore, it offers higher damage threshold compared to existing alternatives. Its compact, passive architecture eliminates the need for external power, making it a robust and efficient alternative to current tunable filtering technologies.