Tunable mid-wave infrared Fabry-Perot bandpass filters using phase-change GeSbTe

Abstract

We demonstrate spectrally-tunable Fabry-Perot bandpass filters operating across the MWIR by utilizing the phase-change material GeSbTe (GST) as a tunable cavity medium between two (Ge:Si) distributed Bragg reflectors. The induced refractive index modulation of GST increases the cavity's optical path length, red-shifting the passband. Our filters have spectral-tunability of ~300 nm, transmission efficiencies of 60-75% and narrowband FWHMs of 50-65 nm (Q-factor ~70-90). We further show multispectral thermal imaging and gas sensing. By matching the filter's initial passband to a CO${}_2$ vibrational-absorption mode (~4.25 $\mu$m), tunable atmospheric CO${}_2$ sensing and dynamic plume visualization of added CO${}_2$ is realized.

arXiv comment13 pages, 5 figures

References in corpus (2)

• Extreme Broadband Transparent Optical Phase Change Materials for High-Performance Nonvolatile Photonics
• Grayscale-to-color: Single-step fabrication of bespoke multispectral filter arrays

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