Optically actuated nanoelectromechanical oscillators

Excitation of biologically functional micro- and nanomechanical structures using optical fields is a recently emerging arena of research that couples the fields of optics, fluidics, electronics, and mechanics with potential of generating novel chemical and biological sensors. We present experimental and theoretical elucidation of optical excitation of resonant nanoelectromechanical systems (NEMS). The modulated optical fields were coupled directly into the NEMS device layer causing amplified mechanical vibrations. Dynamic detection of vibrational characteristics of nanomechanical resonators, fabricated from low-stress silicon nitride and mono crystalline silicon thin film layers, was accomplished using optical interferrometry. We have analyzed the actuation mechanism using finite element modeling, and we found that the dominant actuation mechanism in close proximity of the clamped end was primarily thermal. In contrast, mechanical traveling waves are attributed as possible excitation mechanisms in the far-field regime.