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Diagnostic techniques and UV-induced degradation of the mirrors used in the Orsay storage ring free-electron laser

Journal Article · · Appl. Opt.; (United States)
DOI:https://doi.org/10.1364/AO.24.002762· OSTI ID:5382749
Due to its low gain, the Orsay storage ring free-electron laser necessitates the use of high reflectivity mirrors. Three techniques for measuring the mirror losses are presented, based on cavity decay time measurements using either an external laser, the synchrotron radiation stored in the cavity, or the free-electron laser itself. The high signal-to-noise ratio allowed the detection of loss variations as low as 10/sup -7//sec/sup 1//sup ///sup 2/. From these diagnostics three distinct processes of UV-induced degradation of TiO/sub 2//SiO/sub 2/ dielectric mirrors were identified. One was a surface absorption of the upper SiO/sub 2/-air interface; it was not affected by annealing. The other two corresponded to a volume absorption of the layers which completely recovered after annealing.
Research Organization:
Service de Photophysique, Departement de Physico-Chimie, Centre d'Etudes Nucleaires de Saclay, 91191 Gifsur-Yvette, France
OSTI ID:
5382749
Journal Information:
Appl. Opt.; (United States), Journal Name: Appl. Opt.; (United States) Vol. 24:17; ISSN APOPA
Country of Publication:
United States
Language:
English