Single-crystalline silicon micromirrors actuated by self-aligned vertical electrostatic combdrives with piston-motion and rotation capability
ABSTRACT We present micromirrors actuated by self-aligned, high aspect ratio, vertical electrostatic combdrives with multi-level electrical isolation that allows bi-directional and dual-mode (independent rotation and piston motion) operation. The fabrication process, which requires only front-side processing, is based on self-aligned deep-reactive ion etching (DRIE) of silicon-on-insulator (SOI) wafers with two device layers. The two oxide layers between the device layers provide electrode isolation and etch stops for thickness control. Self-alignment of electrostatic combs in the two device layers is accomplished by creating masking features in the upper layer that are transferred into the lower layer. The masking features are typically removed, but in some cases they remain as an integral part of the completed device. SEM pictures show perfectly aligned vertical combteeth both with and without removal of the masking features. We demonstrate micromirrors of this type with ±9° of optical scanning and 7.5 μm of piston motion under static actuation. Micromirrors designed for resonant scanning have optical scan angles up to ±25° at 13.5 kHz.
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ABSTRACT: This letter describes a free-space optical fiber cross-connect that uses a pair of micromirror arrays to redirect optical beams from an input-fiber array to an output array. This confocal switch architecture is well suited for simultaneous switching of multiple wavelength channels. We show that confocal switches with low insertion loss, low crosstalk, and large port counts can be implemented with surface-micromachined mirror arrays, and we demonstrate a 2/spl times/2 single-mode (1550 nm) switch configuration with insertion loss of -4.2 dB and crosstalk of -50.5 dB. Our micromirror design has sufficient size and angular deflection for scaling to 32/spl times/32 ports.IEEE Photonics Technology Letters 08/2000; · 2.04 Impact Factor
Article: Coherent micromirror arrays.[show abstract] [hide abstract]
ABSTRACT: A one-dimensional, spatial light phase modulator consists of a coherent array of programmable micromirrors. Each micromirror has rotation as well as elevation control to permit high-fidelity, piecewise linear approximations to a desired spatial phase profile. We demonstrate programmable, coherent spatial modulation by configuring a four-micromirror array to act as a blazed diffraction grating, showing five diffraction orders. In sharp contrast, adjustment of each mirror elevation converts the grating into the equivalent of a single, large tilted mirror that reflects only in a new specular direction. Higher-order diffraction is effectively suppressed.Optics Letters 04/2002; 27(5):366-8. · 3.39 Impact Factor
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ABSTRACT: An endoscopic optical coherence tomography (OCT) system based on a microelectromechanical mirror to facilitate lateral light scanning is described. The front-view OCT scope, adapted to the instrument channel of a commercial endoscopic sheath, allows real-time cross-sectional imaging of living biological tissue via direct endoscopic visual guidance. The transverse and axial resolutions of the OCT scope are roughly 20 and 10.2mum, respectively. Cross-sectional images of 500x1000 pixels covering an area of 2.9 mmx2.8 mm can be acquired at ~5 frames/s and with nearly 100-dB dynamic range. Applications in thickness measurement and bladder tissue imaging are demonstrated.Optics Letters 01/2002; 26(24):1966-8. · 3.39 Impact Factor