Abstract
Here we combined experiments and theory to study the optical properties of a plasmonic cavity consisting of a perforated metal film and a flat metal sheet separated by a semiconductor spacer. Three different types of optical modes are clearly identified-the propagating and localized surface plasmons on the perforated metal film and the Fabry-Perot modes inside the cavity. Interactions among them lead to a series of hybridized eigenmodes exhibiting excellent spectral tunability and spatially distinct field distributions, making the system particularly suitable for multicolor infrared light detections. As an example, we design a two-color detector protocol with calculated photon absorption efficiencies enhanced by more than 20 times at both colors, reaching ~42.8% at f1 = 20.0THz (15μm in wavelength) and ~46.2% at f2 = 29.5THz (~10.2μm) for a 1μm total thickness of sandwiched quantum wells.
Highlights
Infrared (IR) technology is developing rapidly in recent decades due to numerous application requests from sciences, health, security and industry [1,2,3,4,5,6]
The spectroscopic features of the target’s emission are completely neglected. These characteristics restrict single-color quantum well infrared photodetectors (QWIPs) from wider applications such as remote sensing where accurate temperature sensing of the target with unknown emissivity is needed or gas monitoring in which the spectroscopic fingerprints are crucial [8]
In the imaging applications, simultaneous detection at several wavelengths is highly desired to obtain the full message of a target [9]
Summary
Infrared (IR) technology is developing rapidly in recent decades due to numerous application requests from sciences, health, security and industry [1,2,3,4,5,6]. The spectroscopic features of the target’s emission are completely neglected These characteristics restrict single-color QWIPs from wider applications such as remote sensing where accurate temperature sensing of the target with unknown emissivity is needed or gas monitoring in which the spectroscopic fingerprints are crucial [8]. For a recently proposed multicolor detector, photo-coupler consisting of multiple independently optimized gratings was designed [9,11] It appeared rather complicated and its performance seemed to be still restricted by its low light coupling efficiencies. Stimulated by the discovery of extraordinary optical transmission in periodically perforated metallic plate a decade ago, plasmonic structures began to draw intensive attention in designing high-efficiency photo-couplers for optoelectronic applications [13,14,15], thanks to their strong capabilities of coupling far-field light to near field and controlling the light in a nano-scale. We design a realistic two-color infrared detector by combining our cavity with two quantum-well (QW) layers, and show that the detection performances of the device can be enhanced significantly with respect to the nonplasmonic case
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