Page 154 - An Introduction to Microelectromechanical Systems Engineering

CHAPTER 5
MEM Structures and Systems in Photonic

Applications

“Our Technology and Engineering Emmy Awards have always honored the innova-
tors that move our industry forward.”
—Peter O. Price, President of the National Television Academy
®
on the Emmy Award to Texas Instrument’s Digital Light
Processing™ (DLP) Technology, October 2003.

The penetration of MEMS technology in photonic applications is one that evokes in
many minds stories of success. What made MEMS successful is that in many
instances, it enabled new functionality by miniaturizing and arraying optical ele-
ments. Two notable markets and applications have benefited greatly from MEMS:
displays and optical fiber communications. In displays, the Digital Light Processing
(DLP™) technology from Texas Instruments of Dallas, Texas, has become a stan-
dard in small- and large-screen projection of digital images, with the Digital Mirror
Device™ (DMD) at its core. In fiber-optical communications, there are a myriad of
MEMS-based components in tunable lasers, optical switches, and optical attenua-
tors, all key elements in transmitting data through optical fibers. But in hearing
these success stories, one should not forget that the systems that are enabled by these
MEMS-based components are very complex and encompass in their operation a
multitude of technologies, with MEMS being just one of them. It is the convergence
of all of these technologies that makes them collectively a success.
This chapter first describes in detail three commercially available products in
imaging applications: an infrared image sensor and two image-projection devices. It
then provides detailed insight into the operation of four types of products used
in fiber-optical telecommunications: tunable lasers, wavelength lockers, optical
switches, and variable optical attenuators. These components source and manipu-
late light as it travels within an optical fiber carrying information.

Imaging and Displays

Infrared Radiation Imager
Demonstrations of micromachined infrared bolometers and sensors have existed for
many years, but the uncooled two-dimensional infrared imaging array from Honey-
well, Inc., of Minneapolis, Minnesota [1], stands out in the crowd and competes
effectively with traditional designs involving cooled cameras based on group II-VI
compound semiconductors.

133