Surface-micromachined microoptical elements and systems

Optical systems are ubiquitous in the present-day societal fabric, from sophisticated fiber-optic telecommunication infrastructure to visual information display, down to mundane chores such as bar-code reading at the supermarket. Most of these existing systems are built from bulk optical components, as they have been for many years. Just as miniaturization and batch-process production have revolutionized electronics, similar advances in optics will certain greatly expand its applications and markets. Production techniques for optical systems that employ the emerging micro-electromechanical systems (MEMS) technologies give promise of achieving this success. Simple micromechanical fabrication techniques are already employed in fiber-optic components to produce what is generally described as silicon-optical-bench systems. New developments, especially those permitting the use of microactuated structures, make substantial increases in system sophistication possible. Surface micromachining, in which microoptical systems are batch-fabricated and placed on top of a silicon wafer, has become a promising approach to this progression. With the demonstration that surface-micromachined elements can be "folded" out from the plane in which they are constructed, an important new degree of design freedom has emerged. This paper examines some of the results obtained and attempts to project possibilities for surface micromachining in future optical systems.