We describe a new type of high-performance IR sensors based on ultrathin lithium niobate (LN) resonant mechanical resonators. Optimal IR absorption will be achieved by nanometer-thin metal films that are impedance matched to free space; narrowband spectral response will be achieved by metamaterials patterning. LN provides many attractive features as compared to existing IR sensor materials, including strong piezoelectric coupling, large temperature coefficients, and favorable thermal conductance and capacitance. Additionally, recent advances in LN-on-insulator (LNOI) technology now permit exceptional film thickness and stress control, making it feasible to create ultrathin phononic structures that rival SiN-based IR sensors – but promise greatly enhanced sensitivity and temporal resolution.
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