Hybrid Micro-Electro-Mechanically Tunable Optical Filter

Air Force Research Laboratory

Wednesday, October 01 2008

Potential applications include optical communications, detection of chemicals, signal processing, and sensing.

A prototype hybrid micro-electro- mechanically tunable optical filter (MEM-TF) based partly on an electrostatic-actuation principle has been built and tested as an essential component needed for the further development of a prototype micro-electro- mechanically tunable vertical- cavity surface emitting laser (MT-VCSEL). In turn, MT-VCSELs are needed as essential controllable-wavelength sources in diverse advanced optoelectronic devices and systems including, for example, wavelength-division multiplexers in fiber-optic communication systems; lightweight, compact, portable spectroscopic instruments for detecting chemical and biological warfare agents; holographic memory devices; fiber-optic sensors; optoelectronic signal-processing systems; and remote-sensing systems. The development of the prototype MEM-TF also has additional significance in that it demonstrates the merit of the hybrid approach (in comparison with the monolithic-integration approach) to design and fabrication of some advanced optoelectronic devices.

As used here, “hybrid” refers to the design and fabrication of a MEM-actuated optoelectronic device as an assembly, in contradistinction to a monolithic unit: In the hybrid approach the optical component(s) and the micro-electro-mechanical actuation component(s) of a device are first fabricated as separate units, then bonded together. The hybrid approach makes it possible to overcome limitations on design, fabrication, and function inherent in the monolithic-integration approach. In the hybrid approach, there is greater design flexibility in that designs of different components can be optimized separately and the components can be made from different materials that are not amenable to fabrication of the device a monolithic unit. Moreover, in the hybrid approach, unlike in the monolithic-integration approach, defective components identified in wafer-level pre-testing can be discarded prior to completing fabrication of devices.