Spectral and thermal management of hexagonal resonant structures for flexible opto-electronic transducers

Efficient on-chip optoelectronic devices in sensing and energy harvesting rely on the combination of subwavelength designs and multiphysical effects. In this contribution, we experimentally analyze and computationally model the optical performance of a hexagonal two-dimensional cluster placed over a silicon substrate and separated by a dielectric layer. Its reflectance has a dip in the long wavelength infrared band. This resonance is due to the generation of localized surface plasmons at the hexagonal surface. Our experimental results validate the multiphysics computational model which can be used to improve its performance as thermal detectors on flexible substrates. In this case, the model combines computational electromagnetism and heat transfer analysis to obtain the temperature distribution in the device. From this analysis, we have designed a thermal transducer based on a metasurface. It consists of a stacked arrangement made of a periodic hexagonal metallic array, a semiconductor ultra-thin layer, a metallic mirror, and a flexible substrate made of polyimide. The structure presented in this work behaves as a spectral selective surface with a resonant wavelength determined by the size of the hexagonal elements and the configuration of the multilayer. Our results show that this device has a time constant in the order of a few milliseconds (2.3 ms). This fast response can be useful in a wide variety of applications such as high speed thermal sensing and energy harvesting.