Microdisplay Innovation Driving Optical Switch Development

One of the hottest technology sectors right now is the all-optical switch for fiber-optic communications and data networks. Interestingly, its developers are leveraging technologies produced for microdisplays in a quest to supply components to drive huge increases in network bandwidth.

The idea behind an optical switch is to allow the routing of optical signals from fiber optic to fiber optic by remaining entirely in the optical domain. Currently, optical pulses are converted to electrical signals, analyzed to determine which direction to send them, and converted back to optical pulses. Optical switching avoids these conversions, improving performance and lowering cost.

For example, imagine having to route light from one optical fiber to any of a dozen other fibers. If a moveable mirror was placed opposite the output of the fiber, then the angle of the mirror could be adjusted to redirect the reflected light to the correct fiber.

Cypress Semiconductor Corp., San Jose, Calif., will develop devices for this type of operation by leveraging technology pioneered by Silicon Light Machines (SLM), Sunnyvale, Calif. SLM has developed a device with 1-by-1080 resolution for a high-definition laser projection system that Sony hopes to commercialize. The technology can be used to steer fiber-optic light beams.

Called a Grating Light Valve (GLV), SLM's technology is based on all-silicon microelectromechanical-systems (MEMS) technology. A series of tiny interleaved fingers is moved up or down by applying a voltage to create an optical interference grating. This effect modulates light in a projection system, or steers light in an optical switch.

DigiLens Inc., Sunnyvale, Calif. has developed an electronically switchable Bragg grating (ESBG) technology. With it, the company has demonstrated the first prototype of an optical switch. The device, a two-channel Dynamic Spectral Equalizer (DSE), allows the real-time adjustment of power distribution within a dense wavelength-division multiplexed (DWDM) system. It helps ensure spectral flatness across all wavelengths in the system.

The DSE employs the ESBG technology to fabricate a switchable version of the industry-standard fiber Bragg gratings used to filter hundreds of wavelengths of light within DWDM networks. This technology allows light to be manipulated in many creative ways and provides the foundation for a new family of customizable, low-cost optical switch components.

Also jumping into the optical components market is a new subsidiary of Microvision Inc., Bothell, Wash. The company, Lumera Corp., has obtained an exclusive worldwide license from the University of Washington, Seattle, to build upon theoretical groundwork laid by Larry Dalton and Bruce Robinson. Their new materials system embeds chromophores into a polymer substrate. Applying a voltage changes the polarization state of the molecules, permitting the direction of light through the material to be controlled.

Lumera's polymer materials will enable active components, such as electro-optic modulators, that feature a combination of fast switching speeds with the lowest drive voltages and optical losses. Prototype devices have already achieved record-setting bandwidths in excess of 100 GHz and operating voltages below 1 V in demonstrations at commercial and government research labs. Lumera expects to make prototype devices available to customers for testing this year, with commercial production scheduled to begin in 2002.