Chorum Technologies Announces Issuance of Four Patents for Optical Networking Technologies.

Business Editors

RICHARDSON, Texas--(BUSINESS WIRE)--May 21, 2001

Optical Cross-Connect Network Patent Protects Fundamental Technology

in Chorum PolarWave(R) Optical Slicer(R) Filter Products

Chorum Technologies, a leading provider of all-optical processors and subsystems, today announced that the U.S. Patent and Trademark Office has issued four U.S. patents for its proprietary optical networking technologies.

U.S. Patent No. 6,175,432, "Multi-Wavelength Cross-Connect Optical Network," is directed to wavelength routing of optical channels in an optical network to support multiplexing and demultiplexing of WDM optical signals. The patent's co-inventors are founders of Chorum Technologies: Dr. Kuang-Yi Wu is vice president of technology and Dr. Jian-Yu (J.Y.) Liu is CTO.

"The '432 patent protects core technologies common to many PolarWave(R) optical Slicer(R) Filter products," said Dr. J.Y. Liu, Chorum Technologies CTO. "In this respect, this is a fundamental patent that transcends our multi-product optical filter offerings."

Chorum Technologies also received three additional patents:

1. U.S. Patent No. 6,208,442, entitled "Programmable Optical

Multiplexer," is directed to a device for multiplexing or

demultiplexing a WDM optical signal.

2. U.S. Patent No. 6,201,593, entitled "Optical Communication

System Having a Liquid Crystal Routing Switch," is directed to

a hybrid analog/binary electro-optical modulator using a

twisted nematic liquid crystal structure that achieves both a

high extinction ratio and a rapid switching speed.

3. A reissued patent, U.S. Patent No. RE37,044, entitled "Tunable

Add/Drop Optical Filter," is directed to a tunable add/drop

filter that utilizes the unique operational characteristics of

a non-reciprocal optical setup and a reciprocal optical setup

for wavelength routing, and a tunable filter for wavelength

selection.

Chorum Technologies has a patent portfolio of 27 issued U.S. patents and more than 30 pending patent applications directed to its proprietary optical networking technologies.

About Chorum Technologies

Chorum Technologies is a leading provider of all-optical processors and subsystems in the fast-growing fiber-optics market. Chorum Technologies' PolarWave(TM) family of optical filtering, switching, routing and processing technologies enables networks that are faster, more flexible and more cost effective than today's networks. Chorum Technologies was founded in 1996 and is based in the Telecom Corridor(R) of Richardson, Texas. For more information, visit www.chorumtech.com.

PolarWave, PolarModule and PolarTune are trademarks of Chorum Technologies. Telecom Corridor(R) is a registered trademark of the Richardson Chamber of Commerce.