Electrically Reconfigurable Nonvolatile Flatband Absorbers in the Mid-Infrared with Wide Spectral Tuning Range

While recent advances in reconfigurable photonics have provided new avenues for manipulating light on the subwavelength scale, on-demand control of infrared absorption remains elusive. Here, we experimentally demonstrate a plasmonic metasurface based on the phase change material Ge₂Sb₂Te₅ with in situ electrically switchable absorption in the 3 - 5 μm wavelength range. Unlike traditional infrared microstructures based on volatile phase-change materials, our device does not require continuous application of external stimuli to maintain its optical state, thus enabling zero static power operation. Furthermore, the 400× deep-subwavelength field localization supported by our device allows robust tuning of its absorptivity and makes it independent of the angle of incidence, thus enabling flatband behavior. We conduct switching of our device by using rapid thermal annealing and reversible switching by using electrical pulses over 26 cycles. Our device provides new avenues for infrared absorption control and serves as a steppingstone for the next generation of midwave infrared photonics.