Abstract
The signal-to-noise ratio of infrared photodetectors can be improved by using resonant cavities, whereas the enhancement effect usually occurs in a narrow wavelength range. Here, we propose a dual-mode plasmonic resonant cavity which can enhance the performance of infrared photodetectors in a wide range of wavelengths from 3.5 \(\mu\)m to 5.5 \(\mu\)m. The optical cavity consists of an Au grating, an ultrathin (310 nm) detective layer of mercury cadmium telluride, and an Au film, which can exhibit nearly perfect absorption at resonant wavelengths with using optimal parameters. For wavelengths from 3.5 \(\mu\)m to 5.5 \(\mu\)m, the wavelength-averaged absorption in the detective layer can also be 62%, about 12 times of that without the resonant cavity. Such a high enhancement of absorption can occur for incident light in a broad range of angle (\(\theta <45^{0}\)) and with different polarizations.
Highlights
Infrared photodetectors and imaging systems are important in applications including night vision, environmental monitoring, and astronomy research [1]
We propose a plasmonic resonant cavity which can enhance the performance of infrared photodetectors in a broad range of wavelengths from 3.5 μm to 5.5 μm
The optical cavity consists of an Au grating, an ultrathin (310 nm) detective layer of mercury cadmium telluride (MCT) [4], and an Au film, where the metal regions serve as electric contacts
Summary
Infrared photodetectors and imaging systems are important in applications including night vision, environmental monitoring, and astronomy research [1]. The photonic structure under study is an MCT layer with thickness t, which is in the x-y plane and sandwiched between an Au grating and an Au film, as shown in Fig. 1a and b.
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