Optical Micro-Electro-Mechanical Systems for Add/Drop Multiplexing and Infrared Spectroscopy

Abstract

Wide ranging efforts in development of various Micro-Electro-Mechanical (MEM) devices over the past twenty years have created a vast collection of novel devices that can be fabricated in numerous ways. As the MEMS field matures it is important to remember the systems aspect the name implies and ensure useful and complete systems are constructed utilizing these wonderful devices. This thesis focuses on two different areas of application for optical MEM systems. The first is a system for optical telecommunications networks that enables an optical add/drop multiplexer, also frequently called a wavelength selective switch. Wavelength selective switches anticipate the need for inexpensive optical switching components with the extension of the optical domain of telecommunications to the end user through fiber to the home. The wavelength selective switch studied is based on the hybridization of a MEMS based optical switch with a particular type of planar lightwave circuit, or on-chip waveguiding device, called an Arrayed Waveguide Grating (AWG). Three separate MEMS switches were implemented into this type of system: a lateral fiber actuator, a scanning micro-mirror, and a binary micro-mirror array. The binary micro-mirror array displayed the greatest performance and is additionally advantageous because of the possibility of further integration. This implementation of a wavelength selective switch provides excellent optical networking properties and performance at low power and with a small device area compared to other switch implementations. Additionally, the system is scalable as the network increases in port count and channel density. The second system studied is an optical gas spectrometer. A scanning MEMS mirror was used with various additional optical components to create a Non- Dispersive Infra-Red (NDIR) gas detector. The MEMS mirror is used in conjunction with a Linear Variable Filter (LVF) to scan a particular range of IR radiation. By detecting the transmission spectrum within the IR radiation band, detection of gases based on their unique radiation absorption pattern can be carried out. Detection of CO2 in concentration ranges from 400ppm to a few percent was performed. Simultaneous detection of multiple species is possible. The system offers a potentially portable and inexpensive gas spectrometer with accuracy necessary for various commercial needs.