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Mode Transition-Discrimination Photonic Logic Device



Technical Challenge:

Prior semiconductor laser photonic logic devices using single-mode lasers and gain quenching suffered from low gain, high power consumption, and relatively large size. Cross-talk between the input signals and the logic device outputs have been a problem; output signal contrast has also been a problem.


This invention is a semiconductor laser that performs logic functions by using a multimode region (mode transition region) configured with mode discriminating outputs (using spatial filtering) and optical input regions. The logic function performed (NAND, NOR, XOR, latch, etc.) is a function of CW bias currents supplied to electrical contacts on the laser and the optical signals present on the optical inputs of the device. The essence of this device is that there is one region where mode transitions can occur in response to an input optical signal and a second region where the modes are discriminated (or isolated). The discrimination function allows the cascade of specific modes to other devices and is an important part of the execution of the logic function. The fabrication of the device uses standard microelectronics processing tools. The device uses the same wavelengths and polarizations for the input and output signals. Compared to previous laser logic devices, this invention is designed to be smaller, faster, more readily integrated, and having lower power consumption.

Demonstration Capability:

Test devices have been fabricated and are being evaluated.

Potential Commercial Application(s):

This device can be employed in optical network switching and routing applications and in high-speed, all optical data processing applications.

Patent Status:

Issued - United States Patent number 7,010,187

Reference Number: 1391

If you are interested in exploring this technology further, please express your interest in writing to the:

National Security Agency
NSA Technology Transfer Program
9800 Savage Road, Suite 6541
Fort George G. Meade, Maryland 20755-6541


Date Posted: Jan 15, 2009 | Last Modified: Jan 15, 2009 | Last Reviewed: Jan 15 2009