Thermo-Mechanical Coupling Mechanism in NEMS Resonators

An optically thin resonator suspended over a substrate and illuminated with a laser forms an interference field that couples deflection of the resonator to absorption within it. For high enough laser powers, such resonators have been shown to be interferometrically transduced to stable oscillations due to the feedback between heating and deflection. The coupling between thermal stresses, deflection, and absorption is the driving mechanism of such oscillations. In this work we study the deflection of doubly supported micro-beams under steady state heating, and illustrate the role of thermal strains and deformation of the beam supports on deflection and ultimately on the laser power level needed to induce stable oscillations.