Metasurfaces for Enhancing Light Absorption in Thermoelectric Photodetectors

Abstract

Metasurfaces can be used to enhance the absorption in metallic and dielectric thin films. Taking advantage of this property, we experimentally demonstrate the use of a commercially available thermoelectric device as a thermoelectric photodetector by integrating it with a metallic metasurface array operating as an absorption enhancer for both the visible and the short-wave infrared. Electrical measurement shows that the responsivity of the nanostructured region is an order of magnitude higher than the flat film region. The absorption spectrum and correspondingly the spectral response of the device can be tailored by optimizing the metasurface dimensions. As such, the device can be used as a multiband photodetector for diverse applications.

All-dielectric thermonanophotonics

“…In optoelectronics, smart nanostructuring of semiconductors can lead to a breakthrough in the optimization of thermo-electrical effects, [254] where the optimal absorption and temperature distribution at nano-/microscales are highly desirable. Moreover, thermal management is crucial for optimization of nanolasers and nano-LEDs, where overheating is a parasitic effect reducing light-emitting properties.…”

Tunable Metasurface Using Thin-Film Lithium Niobate in the Telecom Regime

“…As the MEMS can work in high frequencies, it still requires mechanical movement in the device. Additional approaches like the thermo-optic effect, , phase changing media, − structural reconfigurations, , and electrochemical or chemical reactions demonstrate a large refractive index shift, yet they typically exhibit a slow response rate and are not applicable for high-speed applications such as LIDAR or communication. Another approach leverages the electro-optic effect (EO), which is appropriate for high-speed modulation, but the modulation strength is usually relatively small …”

Electro-optic metasurface-based free-space modulators

“…24 The fundamentally thin nature of metasurfaces poses daunt-ing challenges to the realization of dynamic metasurfaces, because the interaction length is severely limited. Several approaches do exist, however, to achieve efficient tunability by exploiting phase change materials, [25][26][27] the thermo-optic effect, 28,29 or structural reconfigurations, 30,31 which all exhibit significant refractive index changes, but are inherently slow. Another approach involves the use of microelectromechanical system (MEMS) configurations, that allow one to realize significant tuning of the optical path length or actuate an otherwise static metasurface, with the switching speed being still limited due to the necessity of mechanical movements within the device.…”