Controlling IR Thermal Emission with Metasurfaces

In order to shape an Infrared (IR) beam, a number of optical components have to be used. These include a IR source on the first place, a filter to control the spectrum, a polarizer and a retardation plate to control the polarization state and a lens to collimate the beam. Each component is bulky and has a transmission factor smaller than one. It is thus difficult to envision a lighting system within a micrometer thin device that could fit in any handheld device. Such an achievement can be done using light emitting metasurfaces.<br/>In this talk, we will first explain what are metasurfaces and what can be achieved with them. We will describe some examples of metasurfaces operating in transmission by diffracting an incident beam. They can be used to steer an incident beam, modify its polarization or focus it.<br/>Incandescent metasurfaces merge metasurfaces to control phase fronts and thermally excited random current densities emitting IR radiation. They are inherently different from metasurfaces as they are not illuminated by an incident coherent beam. We will discuss the operating principle of incandescent metasurfaces and their application to control the directivity, emission spectrum, polarization and intensity modulation beyond 10 MHz [1-2].<br/><br/>1. L. Wojszvzyk, A. Nguyen, Anne-Lise Coutrot, C. Zhang, B. Vest, J.J. Greffet, An incandescent metasurface for quasimonochromatic polarized Mid-Wave Infrared emission modulated beyond 10 MHz, Nat. Commun <b>12</b>, 1492 (2021).<br/>2. A. Nguyen, J.-P. Hugonin, A.-L. Coutrot, E. Garcia-Caurel, B. Vest, J.-J. Greffet, Large circular dichroism in the emission of an incandescent metasurface, Optica <b>10</b>, 232 (2023).