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Title: Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1261084
Report Number(s):
SLAC-PUB-16691
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Journal Name: Conf.Proc.C110328:277-279,2011; Conference: Particle Accelerator, 24th Conference (PAC'11) 28 Mar - 1 Apr 2011, New York, USA
Country of Publication:
United States
Language:
English
Subject:
Accelerators,ACCSYS

Citation Formats

Soong, K., Byer, R.L., McGuinness, C., Peralta, E.A., Colby, E., and /Stanford U. /SLAC. Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials. United States: N. p., 2016. Web.
Soong, K., Byer, R.L., McGuinness, C., Peralta, E.A., Colby, E., & /Stanford U. /SLAC. Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials. United States.
Soong, K., Byer, R.L., McGuinness, C., Peralta, E.A., Colby, E., and /Stanford U. /SLAC. 2016. "Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials". United States. doi:. https://www.osti.gov/servlets/purl/1261084.
@article{osti_1261084,
title = {Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials},
author = {Soong, K. and Byer, R.L. and McGuinness, C. and Peralta, E.A. and Colby, E. and /Stanford U. /SLAC},
abstractNote = {},
doi = {},
journal = {Conf.Proc.C110328:277-279,2011},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 7
}

Conference:
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  • The accelerating gradient in a laser-driven dielectric accelerating structure is often limited by the laser damage threshold of the structure. For a given laser-driven dielectric accelerator design, we can maximize the accelerating gradient by choosing the best combination of the accelerator's constituent material and operating wavelength. We present here a model of the damage mechanism from ultrafast infrared pulses and compare that model with experimental measurements of the damage threshold of bulk silicon. Additionally, we present experimental measurements of a variety of candidate materials, thin films, and nanofabricated accelerating structures.
  • High reflecting mirrors for the wavelength of 514nm were produced with ion-beam sputtering using different process parameters. The optical characteristics were determined by cavity decay time measurement, laser calorimetry and total integrated scatter measurements. The results for single layers of SiO{sub 2} and Ta{sub 2}O{sub 5} were evaluated with respect to an optimisation of the deposition process. Furthermore, coatings were investigated by infrared spectroscopy and RBS. Laser induced damage thresholds of coatings were measured with a pulsed Nd:YAG-laser. Mirrors produced with optimised parameters show absorption values less than 5ppm, and the scatter losses are in the range of 6ppm atmore » 514nm. Adding the transmission loss of the mirrors, this is in good agreement with the results of the cavity decay time measurement. The damage threshold values and the optical losses are discussed and compared to the results of conventional coatings.« less
  • A problem of a laser induced damage to dielectric coatings due to thermal explosion of the absorbing inclusions is investigated. It is shown that major parameters governing damage characteristics of the coatings are band gaps of coating and substrate materials. In particular, damage threshold dependences on a coating thickness and a position of the inclusion in the coating or on the coating-substrate interface are connected with an effect of this fundamental parameter. Experimental data are in qualitative agreement with theoretical predictions.
  • The method developed for investigating laser-surface interactions by measuring the ratio of ablation threshold fluence for a pair of picosecond or subpicosecond laser pulses to the single-pulse ablation threshold, was applied to ZnS (wurtzite)and to the borosilicate glass BK-7. Each sample was exposed to 1000 pulse pairs of 580-nm dye laser radiation. For ZnS, linear absorption was found to be the cause of the cumulative optical damage mechanism; the linear absorption is probably caused by defects states (such as color centers) near the surface. The nonlinear behavior of BK-7 suggests that avalanche ionization could be the damage mechanism. Results formore » both materials show that intrinsic multiphoton absorption mechanisms may not be significant indicators of optical damage mechanisms even when they lead to very high free-carrier densities and energy absorption.« less
  • Theory of pulswidth dependence of laser induced damage threshold (LIDT) in transparent solids is presented. The damage is supposed to be initiated by thermal explosion of absorbing inclusions. The investigation of thermal explosion is based on an analysis of the heat transfer equation and a new approach to solving this equation is developed allowing to study kinetics of thermal explosion without any modeling presentation of an absorption mechanism. It is shown that the key parameter determining a dependence of LIDT upon a laser pulsewidth, {tau}{sub p}, is the heat transfer time, {tau}, from an inclusion to a surrounding medium. Atmore » {tau}{sub p} {much_gt}{tau} a damage threshold is characterized by a laser radiation intensity, whereas at {tau}{sub p}{much_lt}{tau} - by an energy density. The pulsewidth dependence of the LIDT has been investigated for rectangular and gaussian shapes of laser pulses and it has been established that the dependencies considerably differ in these two cases in a range of {tau}{sub p}{approximately}{tau}. An effect of damage statistics, connected with a random spatial distribution of inclusions in a material, is also investigated. For the case of one-type inclusions it is shown: the statistics does not change a functional form of the pulsewidth dependence of the LIDT and correct only the LIDT value by a spot-size factor. Theoretical results are compared with experimental data published by different research groups for the laser damage in a nanosecond-picosecond region.« less