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Laser system Laser system for LCGTfor LCGT

Norikatsu MIONorikatsu MIO

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Power requirement for LGCT Power requirement for LGCT laser laser

780 W

G=11

75 W150 W

50 %

Laser

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Laser system for LCGTLaser system for LCGT

• 150W Output ： Injection locking + MOPA

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Design conceptDesign concept• Injection-locked laser: Stable optical mode

• Power amplifier: Easy operation, Cascadable for higher power operation

Intensity control element

Frequency control element

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Injection locked laserInjection locked laser• Maser laser ：２ -W NPRO

– Innolight Mephisto• Slave ： 100-W ring laser

– Laser module ： Mitsubishi– Resonator and Controller ： U-Tokyo

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Laser module Laser module （（ MitsubishiMitsubishi ））

Two rods and rotator Diffusive reflector +LD

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Slave laserSlave laser• Ring laser with two laser modules

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Output power of the slave Output power of the slave laserlaser

• １２１ W by bidirectional oscillation

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100-W Power laser100-W Power laser

• Injection locking with 2-W master laser (NPRO)

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Realization of single Realization of single frequency oscillationfrequency oscillation

• Scanning Fabry-Perot output

Free

Injection Locking

100-W Single Frequency oscillation by injection locking

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Long term stabilityLong term stability

Continuous operation for more than 6 hours

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MOPA and intensity MOPA and intensity stabilization (test bench)stabilization (test bench)

MasterNPRO

AmplifierFR

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Intensity stabilization Intensity stabilization performanceperformance

Unity Gain freq.30kHz

Loop Gain at 100 Hz 100db

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Ongoing experimentsOngoing experiments• Frequency stabilization of the 100-W laser.• EOM test for high-power laser light.

– MgO-doped Stoichiometric LiNbO3

• Final stage amplifier (50W) will be tested soon.

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Frequency stabilization Frequency stabilization experimentexperiment

• Triangular reference cavity (kHz)• Transmission intensity curve

Feedback system is being developed

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SummarySummary• Basic components for the LCGT laser

have been completed.– 100-W single frequency operation has

been achieved.– Wide range intensity control has been

done by the current-shunt method.• Further experiments for frequency

and intensity control are being performed.