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All-fiber Tunable Bandpass Filter



Technical Challenge:

To provide an all-fiber means for passing one or more selected optical wavelength bands while blocking all others. This filter can be turned on/off, is tunable over a desired optical bandwidth, and has low insertion loss.


This all-fiber tunable bandpass filter is a novel acousto-optic filter fabricated from standard SMF-28 optical fiber. It has a tunability range of about 100 nm and requires less than 5 mW of electronic power. The filter has an insertion loss of < .1 dB and an out-of band transmission loss of 35 dB. Additionally, the transmission power of the selected band is tunable and the back reflection < 60 dB. The band-pass filter can also be reconfigured to operate as a band-stop filter, whereby the transmission of selected optical channels can be reduced or eliminated.

Demonstration Capability:

The technology can be easily demonstrated.

Component(s) Available for Transfer:

The filter can be custom made to meet customer requirements and delivered for trial testing. The only operating requirement is a tunable RF frequency generator that will provide sinusoidal frequencies from 1-40 MHz.

Potential Commercial Application(s):

High performance fiber-optic systems requiring switching, equalization, and tuning; Telecommunication Networks; Integrated Circuit Component Devices.

Patent Status:

Issued: United States Patent Numbers 6580841 and 6647159 (Updated)

Reference Number: 1215-1; 1215-2

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