Design and fabrication method of the MEMS tunable metasurface thermal emitter with free-standing structures

The emergence of tunable metasurfaces has paved the way for dynamic infrared manipulation and played a crucial role in advancing applications such as biochemical sensing and infrared imaging. In this paper, we present a micromachined tunable narrowband thermal emitter with a wide tuning range and a high quality factor by integrating microelectromechanical system (MEMS) reconfigurable metasurfaces with on-chip micro-heaters. Due to the resonance mode coupling of the metasurface and Fabry–Perot cavity, the emission peak can be modulated from 2–14 μm by continuously altering the thickness of the air gap. A versatile scheme for constructing a MEMS reconfigurable metasurface is proposed by combining free-standing all-metallic metasurfaces and silicon-based MEMS actuators, which can eliminate the intrinsic losses and multiple resonances in substrates, substantially increasing the spectral resolutions. A wafer-scaled MEMS microfabrication process is developed and implemented for the devices, indicating a potential for mass production. We further fabricate miniaturized tunable metasurface thermal emitters, realizing a tuning range covering the long wavelength infrared range and experimentally demonstrating the thermal emission capability as well. Our design provides a practical and effective solution for realizing a real-time thermal emission control with high performance and has a promising prospect in achieving highly integrated, low-cost dynamic infrared meta-devices.