Title: Apparatus and method for increasing the bandwidth of a laser beam

Abstract

A method and apparatus using sinusoidal cross-phase modulation, provides a laser pulse having a very broad bandwidth while substantially retaining the input laser's temporal shape. The modulator may be used in a master oscillator system for a laser having a master oscillator-power amplifier (MOPA) configration. The modulator utilizes a first laser providing an output wavelength .lambda. and a second laser providing an output wavelength shifted by a small amount to .lambda.+.DELTA..lambda.. Each beam has a single, linear polarization. Each beam is coupled into a length of polarization-preserving optical fiber. The first laser beam is coupled into the optical fiber with the beam's polarization aligned with the fiber's main axis, and the second beam is coupled into the fiber with its polarization rotated from the main axis by a predetermined angle. Within the fiber, the main axis' polarization defines an interference beam and the orthogonal axis' polarization defines a signal beam. In the interference beam, the first laser beam and the parallel polarized vector component of the other beam interfere to create areas of high and low intensity, which modulates the signal beam by cross phase modulation. Upon exit from the optical fiber, the beams are coupled out and the modulatedmore » signal beam is separated out by a polarization selector. The signal beam can be applied to coherence reducing systems to provide an output that is temporally and spatially incoherent. The U.S. Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory. « less

Inventors:

Wilcox, Russell B ^[1]

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1. Oakland, CA

Issue Date:

Wed Jan 01 00:00:00 EST 1992

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

OSTI Identifier:

868424

Patent Number(s):

5136599

Assignee:

United States of America as represented by Department of Energy (Washington, DC)

Patent Classifications (CPCs):

H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01S - DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT

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H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01S - DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT

H01S3/0057 - {Temporal shaping, e.g. pulse compression, frequency chirping
H01S3/2383 - {Parallel arrangements}
H01S3/2391 - {emitting at different wavelengths}

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DOE Contract Number:  

W-7405-ENG-48

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

apparatus; method; increasing; bandwidth; laser; beam; sinusoidal; cross-phase; modulation; provides; pulse; broad; substantially; retaining; input; temporal; shape; modulator; master; oscillator; oscillator-power; amplifier; mopa; configration; utilizes; providing; output; wavelength; lambda; shifted; amount; delta; single; linear; polarization; coupled; length; polarization-preserving; optical; fiber; aligned; main; axis; rotated; predetermined; angle; defines; interference; orthogonal; signal; parallel; polarized; vector; component; interfere; create; intensity; modulates; phase; exit; beams; modulated; separated; selector; applied; coherence; reducing; systems; provide; temporally; spatially; incoherent; government; rights; pursuant; contract; w7405-eng-48; department; energy; university; california; operation; lawrence; livermore; national; laboratory; output wavelength; power amplifier; modulated signal; laser pulse; laser beam; optical fiber; signal beam; predetermined angle; main axis; master oscillator; broad band; broad bandwidth; phase modulation; livermore national; national laboratory; input laser; output wave; oscillator-power amplifier; modulator utilizes; parallel polarized; lawrence livermore; temporal shape; substantially retain; master oscillator-power; /372/385/