Enhanced polarization photodetection of metallic cavity ensemble through spontaneously configured lateral electrodes.

Metallic cavities show substantial advantages in light confinement, providing opportunities to modulate the optical resonances and absorption. Here, we report on the configuration of horizontally aligned ZnO-nanowires-based metallic cavity ensemble with a light to dark current ratio of similar to 1000. An enhanced polarization photodetection ratio of transverse electric (TE) to transverse magnetic (TM) was experimentally observed compared to the single ZnO nanowire photodetector. Finite difference time domain simulation was performed on the metallic cavities, showing the distinct resonance behaviors under TE and TM light. The confinement by the multi-reflection and optical resonances between the metallic claddings contribute to the high anisotropy ratio. Furthermore, the polarized light absorption in the metallic cavity was studied as well as in the naked nanowire, which reveal a significant dependence on the cavity diameter and wavelength. For the metallic cavities, the absorption ratio of TE to TM show an enhanced value in the range of 300-500 nm wavelength and 85-150 diameter and a reversed value in the range of 400-500 nm wavelength and 17-50 diameter. While for the naked nanowires, the ratio show an apparently opposite value in these two regions. The presented metallic cavities demonstrate a specific paradigm of optical engineering in nanoscale and potentially helps the development of optoelectronic devices.