Enhanced sensitivity of sub-THz thermomechanical bolometers exploiting vibrational nonlinearity

Abstract

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 $\mathrm{\sim 30 \, pW/\sqrt{Hz}}$ NEP for electrical read-out, sub-THz detectors with an optimized absorbing layer.