A novel arc-cantilevers F-P filter with low stress applicated in infrared spectral integrated photodetector chip

Abstract

Infrared spectral detector technology represents a novel detection strategy that combines spatial information with infrared spectral data, expanding the traditional light-intensity image detection in the spatial dimensions (x, y) to include the spectral dimension (x, y, λ). Conventional spectral detection methods often involve system integration grating on the spectrometer, which suffers from drawbacks such as large size and high-power consumption. To overcome these limitations and enable miniaturization application, it is necessary to investigate the development of spectral integrated infrared detector chips, which include a crucial component known as a tunable filter. Our previous experimental work identified an issue with the Fabry-Perot (F-P) filter based on the conventional cantilever beam structure, where excessive surface stress caused tilting of the bridge deck, adversely affecting the filtering quality. In this study, a new tunable F-P cavity filter structure with low surface stress by arc cantilevers was proposed. The Von Mises stress distribution of the bridge surface was analyzed, revealing a 50% reduction in surface stress compared to the traditional right-angle structure. The newly proposed structure demonstrates excellent performance in terms of tunable infrared transmission filtering spectrum. The tunable wavelength range covers 3-5 μm, and the structure achieves a transmission value of 70%. This work establishes valuable theoretical guidance for the fabrication of cantilever microbridge filters in experimental work and their potential future applications in spectrally integrated detector chips.