Transparent conducting oxides (TCOs) based gratings for light absorption in near infrared spectrum

The present work examines the absorption enhancement of Transparent Conducting Oxides (e.g., Aluminum doped Zinc Oxide (AZO), Gallium doped Zinc Oxide (GZO), and Indium doped Tin Oxide (ITO) for widely used telecom spectral window around lambda = 1550 nm. This is by virtue of the fact that the silica-based optical fiber exhibits minimum loss in this window. It is well established that one-dimensional metallic lamellar grating can significantly enhance light absorption through diffraction and excitation of surface plasmon polaritons (SPPs) at the metal-dielectric interface. This results in subwavelength confinement and hence, enhanced optical absorption in the absorbing layer near the grating. The absorption enhancement can be tuned in different spectral regions by controlling grating parameters, such as grating period, grating height, and grating aspect ratio. The present work focused on establishing Transparent Conducting Oxides (TCOs) as effective plasmonic materials for metallic grating to optimize optical absorption in the near-infrared (NIR) spectral region. The role of TCOs and the grating parameters in fine-tuning the optical absorption enhancement is investigated. Moreover, TCO grating-based designs optimized for absorption enhancement in and around the telecommunication wavelength are proposed.