Vibration of a Microbeam Under Ultra-Short-Pulsed Laser Excitation Considering Momentum and Heating Effect

In this study, vibration of a microbeam excited by an ultra-short-pulsed laser considering the momentum and heating effect of the laser beam is investigated. When the laser impacts the microbeam, portion of the photons is absorbed by the beam and their energy will be transformed into heat while the others are reflected. The momentum change of the absorbed and reflected laser photons is considered and modeled as a distributed force on the beam. The absorbed thermal energy yields non-uniform thermal stress causing the beam to vibrate. According to short duration of laser pulse, the non-Fourier conduction equation which takes into account the finite propagation speed of thermal energy, is implemented to the problem and Euler-Bernoulli assumption is made for the beam. The coupled partial differential equations for the deflection and temperature are solved implementing the mode summation method and Laplace transform. Effect of reflectivity, pulse duration and absorption depth are investigated. It should be noted that depth of the thermal absorption and reflectivity can be managed to control the vibration amplitude and phase of the beam vibration.