Optigain, Inc.

Mala Krishnan

Shijun Jiang

Steven P Bastien

Tariq Manzur

An ultra-wide bandwidth optical amplifier for the 1.5 &mgr;m optical band divides the 1520 nm-1610 nm bandwidth into three narrow bandwidths, i.e. C,(1520 nm-1541 nm), C,(1541 nm-1565 nm) and L (1565 nm-1610 nm), and uses three separate erbium doped fiber amplifier blocks, configured in parallel relation and individually optimized to separately amplify the respective bandwidth. Multipath interference is controlled by constructing all three amplifier blocks with the same optical transmission length. The C,and C,band amplifier blocks, which include shorter erbium doped fibers than the L band amplifier block, are physically lengthened using lengths of single mode fiber so that the total length of the optical transmission path of each amplifier block is generally equal. Fiber lengths are controlled to within 500 microns. Selected amplifier blocks further include delay control devices which selectively delay signals passing through the respective amplifier block to provide fine adjustment to signal recombination.

Ultra-wide bandwidth fiber based optical amplifier

A DFB fiber laser comprises a single-mode, rare-earth doped optical fiber having a uniform Bragg grating with a reflectivity of about 90%, and a single-mode, hi-birefringent optical fiber having a uniform Bragg grating with a reflectivity of near 100%. The output end of the hi-bi fiber is coupled to the input end of the doped fiber to form an asymmetrical fiber laser cavity. The input end of the hi-bi fiber is pumped by a light source (laser diode) having a wavelength in the absorption range of the doped fiber. Pump light entering the hi-bi fiber is passed into the doped fiber to produce a stimulated output. The hi-bi fiber provides single polarization operation, acts as an end reflector to provide single longitudinal mode operation in the laser cavity while also providing single sided output.

Asymmetrical distributed feedback fiber laser

A fiber optic transmitter provides integrated creation and amplification of a fiber optic signal from a single pump source. A fiber laser is utilized to produce a signal output and a remnant pump output from a single pump source. The remnant pump output is divided out of the signal path while the signal output is modulated and then recombined with the modulated signal output and passed through an erbium doped fiber which absorbs the pump output to amplify the modulated signal output. The output from the fiber laser is input into a first wavelength division multiplexer (WDM) which divides the pump output from the signal output. The first WDM outputs the signal output on a first output trunk and the pump output on a second output trunk. A modulator is connected to the first output trunk of the first WDM for modulating the signal output. A second WDM having a first input connected to the output of the modulator and a second input connected to the second output trunk (pump output) of the first WDM recombines the signal output and the pump output after modulation of the signal output. The recombined signal and pump outputs are then passed through a rare-earth doped fiber to amplify the modulated signal output.

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Wakefield, RI, United States of America

Mala Krishnan