Nearly total optical transmission of linearly polarized light through transparent electrode composed of GaSb monolithic high-contrast grating integrated with gold

Achieving high transmission of light through a highly conductive structure implemented on a semiconductor remains a challenge in optoelectronics as the transmission is inevitably deteriorated by absorption and Fresnel reflection. There have been numerous efforts to design structures with near-unity transmission, yet they are typically constrained by a trade-off between conductivity and optical transmission. To address this problem, we propose and demonstrate a transmission mechanism enabled by a monolithic GaSb subwavelength grating integrated with Au stripes (metalMHCG). Near-unity transmission of polarized light is achieved by inducing low-quality factor resonance in the air gaps between the semiconductor grating stripes, which eliminates light absorption and reflection by the metal. Our numerical simulation shows 97% transmission of transverse magnetic polarized light and sheet resistance of 2.2 Omega Sq(-1). The metalMHCG structure was realized via multiple nanopatterning and dry etching, with the largest transmission yet reported of similar to 90% at a wavelength of 4.5 mu m and above 75% transmission in thewavelength range from 4 to 10 mu m and sheet resistance at the level of 26 Omega Sq(-1). High optical transmission is readily achievable using any high refractive index materials employed in optoelectronics. The design of the metal MHCG is applicable in a wide electromagnetic spectrum from near ultraviolet to infrared.

Automated summary

The study introduces a new transmission mechanism enabled by a metalMHCG structure to achieve near-unity optical transmission, eliminating light absorption and reflection issues typically seen on semiconductors. By inducing low-quality factor resonance in air gaps, the structure can achieve high transmission rates and is applicable for high refractive index materials in optoelectronics.