| Abstract |
We have demonstrated a simple experimental technique that can be used to measure the nonlinear absorption coefficients in glasses. We determine BK7, UG1, and UG11 glasses to have linear absorption coefficients of 0.0217(+-) 10% cm(sup -1), 1.7(+-) 10% cm(sup -1), and 0.82(+-) 10% cm(sup -1), respectively, two-photon absorption cross-sections of 0.025(+-) 20% cm/GW, 0.035(+-) 20% cm/GW, and 0.047(+-) 20% cm/GW, respectively, excited-state absorption cross-sections of 8.0 x 10(sup -18)(+-) 20% cm(sup 2), 2.8 x 10(sup -16)(+-) 20% cm(sup 2), and 5 x 10(sup -17)(+-) 20% cm(sup 2), respectively, and solarization coefficients of 8.5 x 10(sup -20)(+-) 20% cm(sup 2), 2.5 x 10(sup -18)(+-) 20% cm(sup 2), and 1.3 x 10(sup -19)(+-) 20% cm(sup 2), respectively. For our application, nonlinear effects in 10-cm of BK7 are small ((le) 2%) for 355-nm fluences less than 0.2 J/cm(sup 2) for flat-top pulses. However, nonlinear effects are noticeable for 355-nm fluences at 0.8 J/cm(sup 2). In particular, we determine a 20% increase in the instantaneous absorption from linear, a solarization rate of 4% per 100 shots, and a 10% temporal droop introduced in the pulse, for 355-nm flat-top pulses at a fluence of 0.8 J/cm(sup 2). For 0.5-cm of UG1 absorbing glass the non-linear absorption has a similar effect as that from 10-cm of BK7 on the pulse shape; however, the effects in UG11 are much smaller. |
