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Method of Fabricating Waveguide using Sacrificial Spacer Layer

(patent has issued: 7,599,594)


Fabricating Waveguide and Integrating it into a Laser, Photonic Logic Research, Gain Quenched Laser Logic, Optically Controlled Laser (OCL), and Mode Transition-Discrimination (MTD) Photonic Logic

Technical Challenge:

To provide a controlled integration of active (laser) optical components to passive (waveguide) devices. This technology should be applicable to any application requiring integration of these active and passive devices and is considered multi-use.


This technology provides the ability to change the mirror reflectance of semiconductor lasers that are coupled to integrated waveguides. The laser mirror reflectance is changed in a manner that does not require the use of patterned etch processes, but is compatible with standard microelectronics processes. When reflectance modification of the optical components is required, this method makes use of a sacrificial spacer layer (S2L) to create a gap between optical components, where the width of the gap is resonant with the optical signal present in the optical components. The S2L is also used to create a gap at the edge of the waveguide that provides optical confinement at that waveguide interface. This method offers a simpler, less expensive, and faster process than existing methods today.

Demonstration Capability:

Test devices have been fabricated, which use this method and demonstrate the fabrication of precise gaps using sacrificial spacer layers.

Potential Commercial Application(s):

Provides for the fabrication of semiconductor lasers that are shorter length, lower turn-on power, higher integration density, and a higher modulation rate, compared to semiconductor lasers that do not use S2L resonant gaps. Internal development of these S2L resonant gap integrated lasers is for photonic integrated circuits applied to encryption and could have many industrial/commercial uses.

Patent Status:

A patent application has been filed with USPTO.

Reference Number: 1424-1

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: Apr 20, 2010 | Last Reviewed: Apr 20, 2010