title: Ultra-broadband light trapping using nanotextured decoupled graphene multilayers.
abstract: The ability to engineer a thin two-dimensional surface for light trapping across an ultra-broad spectral range is central for an increasing number of applications including energy, optoelectronics, and spectroscopy. Although broadband light trapping has been obtained in tall structures of carbon nanotubes with millimeter-tall dimensions, obtaining such broadband light-trapping behavior from nanometer-scale absorbers remains elusive. We report a method for trapping the optical field coincident with few-layer decoupled graphene using field localization within a disordered distribution of subwavelength-sized nanotexturing metal particles. We show that the combination of the broadband light-coupling effect from the disordered nanotexture combined with the natural thinness and remarkably high and wavelength-independent absorption of graphene results in an ultrathin (15 nm thin) yet ultra-broadband blackbody absorber, featuring 99% absorption spanning from the mid-infrared to the ultraviolet. We demonstrate the utility of our approach to produce the blackbody absorber on delicate opto-microelectromechanical infrared emitters, using a low-temperature, noncontact fabrication method, which is also large-area compatible. This development may pave a way to new fabrication methodologies for optical devices requiring light management at the nanoscale.
authors.affiliation: Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: José V
authors.initials: JV
authors.lastname: Anguita
authors.affiliation: Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ahmad
authors.affiliation: BAE Systems, Advanced Technology Centre, Sowerby Building (20R), FPC 267, P. O. Box 5, Filton, Bristol BS34 7QW, UK.
authors.forename: Sajad
authors.initials: S
authors.lastname: Haq
authors.affiliation: Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: Jeremy
authors.identifier: 0000-0002-4495-5517
authors.initials: J
authors.lastname: Allam
authors.affiliation: Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: S Ravi P
authors.initials: SR
authors.lastname: Silva
keywords: Broadband light absorption; Optical nanomaterials; blackbody absorber; decoupled multilayer graphene; graphene; high emissivity of infrared radiation; light management; nano-optoelectronics; nanoscale nanomaterials; subwavelength optical absorption