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Proceedings Paper

High power green lasers for gamma source
Author(s): Magali Durand; Pierre Sevillano; Olivier Alexaline; Damien Sangla; Alexis Casanova; Adrien Aubourg; Abdelhak Saci; Antoine Courjaud
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Paper Abstract

A high intensity Gamma source is required for Nuclear Spectroscopy, it will be delivered by the interaction between accelerated electron and intense laser beams. Those two interactions lasers are based on a multi-stage amplification scheme that ended with a second harmonics generation to deliver 200 mJ, 5 ps pulses at 515 nm and 100 Hz.

A t-Pulse oscillator with slow and fast feedback loop implemented inside the oscillator cavity allows the possibility of synchronization to an optical reference. A temporal jitter of 120 fs rms is achieved, integrated from 10 Hz to 10 MHz.

Then a regenerative amplifier, based on Yb:YAG technology, pumped by fiber-coupled QCW laser diodes, delivers pulses up to 30 mJ. The 1 nm bandwidth was compressed to 1.5 ps with a good spatial quality: M2 of 1.1. This amplifier is integrated in a compact sealed housing (750 x 500 x 150 mm), which allows a pulse-pulse stability of 0.1 % rms, and a long-term stability of 1,9 % over 100 hours (with +/-1°C environment).

The main amplification stage uses a cryocooled Yb:YAG crystal in an active mirror configuration. The crystal is cooled at 130 K via a compact and low-vibration cryocooler, avoiding any additional phase noise contribution, 340 mJ in a six pass scheme was achieved, with 0.9 of Strehl ratio. The trade off to the gain of a cryogenic amplifier is the bandwidth reduction, however the 1030 nm pulse was compressed to 4.4 ps. As for the regenerative amplifier a long-term stability of 1.9 % over 30 hours was achieved in an environment with +/-1°C temperature fluctuations

The compression and Second Harmonics Generation Stages have allowed the conversion of 150 mJ of uncompressed infrared beam into 60 mJ at 515 nm.

Paper Details

Date Published: 15 February 2018
PDF: 7 pages
Proc. SPIE 10511, Solid State Lasers XXVII: Technology and Devices, 105111B (15 February 2018); doi: 10.1117/12.2289670
Show Author Affiliations
Magali Durand, Amplitude Systèmes (France)
Pierre Sevillano, Amplitude Systèmes (France)
Olivier Alexaline, Amplitude Systèmes (France)
Damien Sangla, Amplitude Systèmes (France)
Alexis Casanova, Amplitude Systèmes (France)
Adrien Aubourg, Amplitude Systèmes (France)
Abdelhak Saci, Amplitude Systèmes (France)
Antoine Courjaud, Amplitude Systèmes (France)


Published in SPIE Proceedings Vol. 10511:
Solid State Lasers XXVII: Technology and Devices
W. Andrew Clarkson; Ramesh K. Shori, Editor(s)

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