Spatial light modulators for applications in coherent communications, adaptive optics and optical maskless lithography.

摘要

Optical MEMS (micro-electro-mechanical systems) devices have been used in a variety of applications including fiber-optic communications, projection TVs and in biomedical imaging. MEMS-based spatial light modulators (SLM) provide a compact, large scale, and cost-effective solution to these and other applications. In this dissertation, we introduce the design and fabrication of SLMs for three such applications.; Free-space coherent communications between ground based stations and space-based aircraft or satellites, and imaging/targeting of these objects at large distances (>1000km) require wavefront control to correct for aberrations due to the atmosphere in addition to very fast scanning ability. We introduce a scalable prototype of a tip-tilt-piston electrostatic combdrive micromirror array with the ability of the individual mirrors to do 2-dimensional angular deflection for scanning as well as piston deflection for wavefront control.; In NASA's program to search for earth-like planets (ELPs), an optical system with the wavefront corrected to lambda/3000 at the detector is required to resolve very faint ELPs next to very bright stars. In contrast to atmospheric distortion degrading the images for ground-based telescopes, image degradation is mainly due to the polishing errors of the large primary mirror in a space-based telescope. To correct for the polishing errors without introducing additional aberrations, we present a SCS (single-crystal-silicon) continuous facesheet deformable mirror with very good optical quality.; In the IC industry, as masks become prohibitively expensive, there is motivation to use a programmable mask to reduce time and cost in the development and production stage in IC manufacturing. For our third application, we present a piston-type dual-lever actuator mirror array as a programmable mask for optical maskless lithography. We demonstrate the various capabilities of the SLM in optical pattern generation such as sub-grid patterning, line-width modulation, checkboard generated lines and spaces, and vortices. In addition, we experimentally demonstrate the use of a calibration method to improve the sensitivity of the maskless system.; Finally, we present a MEMS scanner with a high reflectivity broadband photonic crystal mirror. 2-D Photonic crystals made from a single dielectric material can achieve higher reflectivity and allow higher processing temperatures than metals and are simpler to fabricate than multi-layer dielectric stacks. These characteristics show potential for wafer-scale encapsulation and simpler integration of these mirrors with optical MEMS devices.