Micromachined mirrors for raster -scanning displays and optical fiber switches.

摘要

Micromachines and micro-optics have the potential to shrink the size and cost of free-space optical systems, enabling a new generation of high-performance, compact projection displays and telecommunications equipment. In raster-scanning displays and optical fiber switches, a free-space optical beam can interact with multiple tilt-up micromirrors fabricated on a single substrate. The size, rotation angle, and flatness of the mirror surfaces determine the number of pixels in a raster-display or ports in an optical switch.;Single-chip and two-chip optical raster display systems demonstrate static mirror curvature correction, an integrated electronic driver board, and dynamic micromirror performance. Correction for curvature caused by a stress gradient in the micromirror leads to resolution of 102 by 119 pixels in the single-chip display. The optical design of the two-chip display features in-situ mirror curvature measurement and adjustable image magnification with a single output lens. An electronic driver board synchronizes modulation of the optical source with micromirror actuation for the display of images. Dynamic off-axis mirror motion is shown to have minimal influence on resolution.;The confocal switch, a free-space optical fiber cross-connect, incorporates micromirrors having a design similar to the image-refresh scanner. Two micromirror arrays redirect optical beams from an input fiber array to the output fibers. The switch architecture supports simultaneous switching of multiple wavelength channels. A 2x2 switch configuration, using single-mode optical fiber at 1550 mn, is demonstrated with insertion loss of --4.2 dB and cross-talk of --50.5 dB. The micromirrors have sufficient size and angular range for scaling to a 32x32 cross-connect switch that has low insertion-loss and low cross-talk.