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Pump-probe method for investigating laser ablation and optical damage threshold mechanisms in optical materials

Conference ·
OSTI ID:144790
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 for 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.
Research Organization:
Lawrence Livermore National Lab., CA (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
144790
Report Number(s):
UCRL-JC--114770; CONF-9309259--5; ON: DE94008291
Country of Publication:
United States
Language:
English