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Communication Dans Un Congrès Année : 2019

Characterization, Integration and Operation of a 100-W Solid State Amplifier in the Advanced-VIRGO Pre-Stabilized Laser System

Résumé

Summary form only given. VIRGO is a 3-km-arm laser interferometer for gravitational wave detection in the 20 Hz-5 kHz frequency band. Its second-generation version, Advanced VIRGO, aims at reducing the detector noise by a factor of ten compared to the first generation, with the progressive deployment of new technologies and equipment [1]. The first detections of gravitational waves with VIRGO were made in August 2017 [2]. For its next scientific observations with an increased sensitivity, a pre-stabilized laser system twice as powerful has been developed. It comprises a new 100-W solid-state amplifier pumped at 878.7 nm. It is the first time such amplifier is integrated in a gravitational wave detector, LIGO detectors using a 70 W amplifier pumped at 808 nm. Power noise, long term power stability, frequency noise, beam jitter and transverse mode quality have been extensively studied and compared to Advanced VIRGO requirements. The pre-stabilized laser system, emitting a continuous wave at 1064 nm, is based on a 17 W laser oscillator, injection locked onto a low frequency noise 500 mW source, followed by the new 100 W amplifier and a 1.6-mperimetre bow -tie shape Fabry-Perot cavity acting as a spatial and temporal mode cleaner. The optical amplifier, manufactured by neoLASE, is based on four Nd 3+ :YVO 4 crystals pumped longitudinally each with 50 W at 878,7 nm coming from volume Bragg grating diode lasers. The pump light is transported by 20 meters of multi mode fi bers deployed between two separate rooms for acoustic and electromagnetic contamination reasons. The fi rst test and characterization campaign was performed in Nice in 2017 followed by the integration at the VIRGO site. The system has been working continuously for commissioning for more than one year. The amplifier delivers 96 W with 17 W input and reaches 100 W with increased input power. No global decrease of the amplifier output power has been so far observed. The relative intensity noise spectrum (Fig. 1-a) is below 10 -4 x(10 Hz/f) 1 / 2 Hz -1 / 2 in the detection band and limited by 13 mA photocurrent shot noise (5x 10 Hz 1/2 ) in the 5-10 MHz band used for modulation. Further power noise reduction is realized by combining passive fi ltering from Fabry-Perot mode cleaners and active power stabilization with an acousto-optic modulator in transmission to reach 2x 10 -9 Hz -1 / 2 in the detector band. The spectrum of the frequency noise added by the amplifier (Fig. 1-b) was measured with a heterodyne interferometer and is lower than 3x 10 -1 Hz/Hz 1 / 2 , far below the master laser oscillator. Those performances are compliant with Advanced VIRGO specifications [1].

Dates et versions

hal-02483903 , version 1 (18-02-2020)

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Citer

Frédéric Cleva, Jean-Pierre Coulon, Fabien Kéfélian. Characterization, Integration and Operation of a 100-W Solid State Amplifier in the Advanced-VIRGO Pre-Stabilized Laser System. 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference, Jun 2019, Munich, Germany. ⟨10.1109/CLEOE-EQEC.2019.8873060⟩. ⟨hal-02483903⟩
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