title: All-Silicon Ultra-Broadband Infrared Light Absorbers.
abstract: Absorbing infrared radiation efficiently is important for critical applications such as thermal imaging and infrared spectroscopy. Common infrared absorbing materials are not standard in Si VLSI technology. We demonstrate ultra-broadband mid-infrared absorbers based purely on silicon. Broadband absorption is achieved by the combined effects of free carrier absorption, and vibrational and plasmonic absorption resonances. The absorbers, consisting of periodically arranged silicon gratings, can be fabricated using standard optical lithography and deep reactive ion etching techniques, allowing for cost-effective and wafer-scale fabrication of micro-structures. Absorption wavebands in excess of 15 micrometers (5-20 μm) are demonstrated with more than 90% average absorptivity. The structures also exhibit broadband absorption performance even at large angles of incidence (θ = 50°), and independent of polarization.
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Kazim
authors.initials: K
authors.lastname: Gorgulu
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Gok
authors.affiliation: UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Yilmaz
authors.affiliation: UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.|Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Kagan
authors.initials: K
authors.lastname: Topalli
authors.affiliation: UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.|Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Necmi
authors.initials: N
authors.lastname: Bıyıklı
authors.affiliation: Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey.|UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.|Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey.
authors.forename: Ali K
authors.initials: AK
authors.lastname: Okyay