Efficient conversion of long-wavelength light into direct current represents a great potential for photodetection, photocatalyst, and photovoltaics, with a variety of applications in sensing, security, defense, and emissive infrared energy harvesting. We propose here a new type of plasmo-electronic nanodevice, engineered as the hyperbolic metamaterial (HMM), to efficiently trap and nonlinearly rectify the incoming infrared radiation. These HMM-based nanodevices are constituted by the periodic, dissimilar metal-insulator-metal (MIM) heterojunctions, whose homogenized material properties enable the perfect absorption of infrared radiation and the localization of optical fields. The nonlinear optical rectification driven by the multiphoton-assisted tunneling in the MIM heterojunctions can efficiently convert the infrared radiation into the DC electricity (photocurrent). Most interestingly, the wideband or frequency-selective photon-to-electron conversion can be controlled via the design of HMM nanostructures. Our theoretical and numerical results demonstrate that the zero-bias responsivity of the HMM-based nanodevices can be up to ~100 mA/W in the mid-infrared regime.
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