A bulk-micromachined electrostatic micromirror has been developed and tested for use in optomechanical microdevices. The silicon micromirror, suspended by two pairs of boron-diffused microbeams, has been fabricated by an anisotropic etching of (110) silicon wafers. The vertical micromirror can be driven parallel to the silicon substrate by the electrostatic force. In a static performance test, stable operation of the micromirror has been observed up to the threshold deflection of 26.5㎛ with the measured threshold voltage of 330V. In a dynamic test, the resonant frequency of the suspended micromirror has been measured as 590Hz, which can be tuned in the ranges of 588~450Hz within the dc bias voltage levels of 50~300V. The present micromirror is applicable to a wide variety of static and dynamic optomechanical microdevices, including optical microswitches, optical shutters, laser-beam choppers, optical filters and optical couplers.
