Abstract
Controlling thermal emission with resonant photonic nanostructures has recently attracted much attention. Most of the work has concentrated on the mid-infrared wavelength range and/or was based on metallic nanostructures. Here, we demonstrate the experimental operation of a resonant thermal emitter operating in the near-infrared (≈1.5 μm) wavelength range. The emitter is based on a doped silicon photonic crystal consisting of a two dimensional square array of holes and using silicon-on-insulator technology with a device-layer thickness of 220 nm. The device is resistively heated by passing current through the photonic crystal membrane. At a temperature of ≈1100 K, we observe relatively sharp emission peaks with a Q factor around 18. A support structure system is implemented in order to achieve a large area suspended photonic crystal thermal emitter and electrical injection. The device demonstrates that weak absorption together with photonic resonances can be used as a wavelength-selection mechanism for thermal emitters, both for the enhancement and the suppression of emission.
Highlights
Controlling thermal emission with resonant photonic nanostructures has recently attracted much attention
Afterwards, the photonic crystal was inspected with an optical microscope and no surface defects or any other degradation of the device was visible, except for a small colour change at the very centre of the photonic crystal strips where the temperature reaches its highest point
We demonstrate that by controlling the doping concentration in silicon and resonantly enhancing the absorption, accurate control over the material’s absorption coefficient is achieved, which allows engineering of the thermal emission peaks of photonic structures without adding additional absorption features into the material
Summary
Controlling thermal emission with resonant photonic nanostructures has recently attracted much attention. The device demonstrates that weak absorption together with photonic resonances can be used as a wavelength-selection mechanism for thermal emitters, both for the enhancement and the suppression of emission. Reference [3] reports a metallic gold structure with an emission peak at 3.85 μ m with a Q factor of approximately 10; reference [7] illustrates a three dimensional (3D) metallic PhC with a peak emission at 1.5 μ m but with a Q factor ≈ 1.7 These examples highlight the utility of photonic resonances for thermal emission control, but for many applications, a narrower emission line is desirable. We show that by introducing a PhC structure into the doped silicon layer, enhanced resonant absorption occurs at the photonic modes of the structure, which generates narrow emission peaks when heated. The image shows the deposited aluminium contact pads at both sides of the PhC structure along with the isolation trench around the entire device
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