Enhanced Sensitivity of Sub-THz Thermomechanical Bolometers Exploiting Vibrational Nonlinearity

A common approach to detecting weak signals or minute quantities involves leveraging the localized spectral features of resonant modes, whose sharper lines (i.e., high Q-factors) enhance transduction sensitivity. However, maximizing the Q-factor often introduces technical challenges in fabrication and design. In this work, we propose an alternative strategy to achieve sharper spectral features by using interference and nonlinearity, all while maintaining a constant dissipation rate. Using far-infrared thermomechanical detectors as a test case, we demonstrate that signal transduction along an engineered response curve slope effectively reduces the detector's noise equivalent power (NEP), achieving <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>∼</mml:mo> <mml:mn>30</mml:mn> <mml:mspace></mml:mspace> <mml:mi>pW</mml:mi> <mml:mo>/</mml:mo> <mml:msqrt><mml:mi>Hz</mml:mi></mml:msqrt> </mml:math> NEP for electrical read-out, sub-THz detectors with an optimized absorbing layer.