Figure 2

IR Measurements and Characteristic Thermal Response of the Broadband Plasmonic Absorber.

(a) Schematic representation of the experimental set-up for infra-red temperature measurement. The left inset illustrates the emissivity measurement. It contains a picture of the used metallic cylinder (left) with a deep hole and the emissivity map generated by the camera software (right); (b) The upper panel contains a post-processed IR image of an absorber membrane during irradiation (the dashed circle indicates the extension of the absorber membrane). The lower panel is the zoomed view on the laser spot and the 3 × 3 pixel window (black square) around the hottest pixel, which are used to determine ΔT_peak. (c) Peak temperature increase as a function of the absorbed power. The dashed line represents a linear fit with zero intercept ΔT_peak = 2.45 * P_abs. (d) Time evolution of temperature increase at maximum incident power (= 60.3 mW, absorbed power = 51.8 mW). The reached peak temperature determines the steady-state value of ΔT_peak, which is shown in (c). The purple curve shows the time evolution of temperature increase obtained for a lower incident power (= 24.8 mW, absorbed power = 21.3 mW).