Metal-oxides based plasmonics for the mid-IR

Speaker: D. Eduardo Martínez.
Organization: Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), de la E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid.

Data:  October 8th, 2021.
Hours: 9.30 hours.
Place: Room B-222 of the ETSI of Telecommunications of the UPM [Cómo llegar]


IR photonics is currently a well stablished field with a wide range of commercial and experimental applications including medicine, biosensing, solar cells, astronomy and surveillance. Despite the huge advances in IR detection, commercial devices must struggle with unavoidable issues emerging from the low-energy range of the spectrum they target. IR photodetectors use materials and systems with low energy transitions for an effective optical absorption. When operating at room temperature, thermal energy of the carriers (kT) become comparable to the energy of the optical transition, resulting in an increased thermal noise.

In the last few decades, the field of plasmonics has provided an innovative approach to this problem, based on the field-enhancement properties of metallic nanostructures. Plasma oscillations in a metal-photodetector interface allow sub-wavelength light confinement that drives to improved absorption efficiency. However, due to their high plasma frequency noble metals are better suited for UV or visible-range photonics.

In this work we introduce CdZnO as a perfect substitute of metals for the mid-IR. Different plasmonic coatings and systems are presented for enhanced mid-IR detection, including gratings and nanoparticle systems. Here, we computationally study the potential gains in power absorption when different photodetectors are coupled with these coatings. In addition to that, experimental gains as high as 2.5x are reported in experimental plasmon-intersubband coupled systems.