Williams Calum, Hong Nina, Julian Matthew, Borg Stephen, Kim Hyun Jung
Opt Express. 2020 Mar 30;28(7):10583-10594. doi: 10.1364/OE.390538.
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 vibrational-absorption mode (∼4.25 µm), tunable atmospheric CO sensing and dynamic plume visualization of added CO is realized.
我们展示了通过利用相变材料锗锑碲（GST）作为两个（锗：硅）分布布拉格反射器之间的可调谐腔介质，在中波红外波段工作的光谱可调谐法布里 - 珀罗带通滤波器。GST 引起的折射率调制增加了腔的光程长度，使通带发生红移。我们的滤波器具有约 300 nm 的光谱可调性、60 - 75%的传输效率以及 50 - 65 nm 的窄带半高宽（品质因数约为 70 - 90）。我们还展示了多光谱热成像和气体传感。通过将滤波器的初始通带与一氧化碳的振动吸收模式（约 4.25 µm）匹配，实现了可调谐大气一氧化碳传感以及添加一氧化碳的动态羽流可视化。
