Study of the response behaviour of micromechanical optical modulator with a square wave driving

In this paper we present a micromechanical optical modulator fabricated by surface micromechanical technique. The modulator provides an ideal tool to investigate the dynamic process of the micromechanical device. The modulator has a series of resonant frequencies determined from the device structure. When the modulator is driven by a square wave, the response waveform depends on the driving frequency. When the driving signal is far less than the resonant frequencies, the response is a damping vibration: a response to the up and down step driving. When the driving signal is close to the main intrinsic frequency, the response is a sinusoidal signal: a response to the first frequency component.