All-Solid-State Optical-Field-Sensitive Detector for Sub-Nanojoule Pulses Using Metal–Insulator Hybrid Nanostructure

We develop an all-solid-state, metal–insulator hybrid device that is capable of detecting an optical field of sub-nanojoule pulses via optical-field-induced tunneling. The tunneling at a gold/aluminum-oxide (Al2O3) interface is driven by an enhanced near-field of a metal–insulator–metal plasmon. Compared to a conventional device with a metal/air interface, we achieve a substantial increase in the tunneling current because of a reduced barrier height, a reduced effective mass of tunneled electrons, an increased plasmonic near-field enhancement, and a denser array of nanoantennas. The device exhibits a remarkable sensitivity to the optical field, which confirms the optical-field-induced tunneling as an emission mechanism. Furthermore, complete encapsulation of the nanoantennas with dielectric materials, coupled with efficient photocurrent generation, improves the durability against optical irradiation.