DocumentCode :
1913466
Title :
High-power UV light generation in picosecond pulse trains
Author :
Martyanov, M. ; Divall, Marta ; Gacheva, E. ; Hessler, Christoph ; Fedosseev, Valentin
Author_Institution :
Eur. Organ. for Nucl. Res. (CERN), Geneva, Switzerland
fYear :
2013
fDate :
12-16 May 2013
Firstpage :
1
Lastpage :
1
Abstract :
This paper focuses on the investigation of detrimental UV induced effects during fourth harmonic generation (FHG) in BBO crystals. An accumulation of partly recoverable UV two-photon induced optical defects has been observed in the 140 s train generated by frequency quadrupled 1.5 GHz Nd:YLF laser with about 300 W UV power per train, even for a relatively low peak pulse intensity of about 100 MW/cm2. BBO crystals with length of 4.2, 8.5 and 12 mm have been tested. In a shorter crystal less distortion have been observed for the same UV output power. Although the growth of optical defects is attributed to the UV two-photon absorption, the already accumulated defects lead to a linear absorption of green and UV co-propagating pulses which in turn results in train envelope degradation due to deterioration of a phase-matching and thermal beam distortion. The UV beam exhibited focusing behavior on a short distance (crystal length) which cannot be explained by temperature dependence of BBO refractive indexes. The UV beam focusing is addressed as a strong photo-elastic effect, caused by the stress induced by essentially non-uniform temperature distribution inside the beam propagation volume.
Keywords :
barium compounds; laser beams; light propagation; neodymium; optical distortion; optical focusing; optical harmonic generation; optical phase matching; photoelasticity; refractive index; solid lasers; two-photon processes; ultraviolet radiation effects; BBO; BBO crystals; FHG; UV beam focusing; UV copropagating pulses; UV induced effects; UV two-photon absorption; UV two-photon induced optical defects; YLF:Nd; beam propagation volume; crystal length; focusing behavior; fourth harmonic generation; frequency 1.5 GHz; frequency quadrupled Nd:YLF laser; green pulses; high-power UV light generation; linear absorption; nonuniform temperature distribution; phase-matching deterioration; photoelastic effect; picosecond pulse trains; refractive indexes; size 4.2 mm to 12 mm; thermal beam distortion; train envelope degradation; Crystals; Frequency conversion; Laser beams; Optical distortion; Power lasers; Radio frequency;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Lasers and Electro-Optics Europe (CLEO EUROPE/IQEC), 2013 Conference on and International Quantum Electronics Conference
Conference_Location :
Munich
Print_ISBN :
978-1-4799-0593-5
Type :
conf
DOI :
10.1109/CLEOE-IQEC.2013.6800883
Filename :
6800883
Link To Document :
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