Title: High power, high beam quality regenerative amplifier

Abstract

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct themore » beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced. « less

Inventors:

Hackel, Lloyd A ^[1]; Dane, Clifford B ^[1]

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+ Show Inventor Affiliations

1. Livermore, CA

Issue Date:

Fri Jan 01 00:00:00 EST 1993

Research Org.:

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

OSTI Identifier:

868898

Patent Number(s):

5239408

Assignee:

Regents of University of California (Oakland, CA)

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

H01S3/06 - Construction or shape of active medium
H01S3/08095 - {Zig-zag travelling beam through the active medium}
H01S3/093 - focusing or directing the excitation energy into the active medium
H01S3/10076 - {using optical phase conjugation, e.g. phase conjugate reflection}
H01S3/2341 - {Four pass amplifiers}
H01S3/235 - {Regenerative amplifiers}

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DOE Contract Number:  

W-7405-ENG-48

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

power; beam; quality; regenerative; amplifier; laser; generates; peak; energy; pulse; output; beams; enabling; generation; x-rays; x-ray; lithography; manufacturing; integrated; circuits; shaped; optical; path; limited; components; including; polarizer; passive; 90; degree; phase; rotator; plurality; mirrors; relay; telescope; medium; placed; close; image; plane; reduce; diffraction; perturbations; limit; intensity; spiking; makes; passes; transit; increase; loss; ratio; input; diverted; sbs; conjugator; proceeds; equal; opposite; direction; reducing; master; oscillator; inputs; isolation; cell; faraday; pockels; transmits; polarization; rotation; rotates; proceeding; direct; preserved; nearly; produced; sbs phase; beam quality; pulse output; output beams; shaped optical; image plane; input beam; x-ray lithography; opposite direction; power output; output beam; optical path; laser amplifier; integrated circuits; integrated circuit; peak power; diffraction limited; master oscillator; components including; regenerative amplifier; regenerative laser; peak intensity; phase conjugator; degree phase; enabling generation; /359/372/