Laser damage thresholds of CdSiP2 have previously been measured at wavelengths of 1064 nm and 2090 nm using nanosecond durations lasers1,2 and at 1940 nm using a continuous wave laser3. In the continuous wave measurement attempted in the past3, the CdSiP2 sample was found to withstand an irradiance of 150 kW/cm2 for over 60 seconds without any damage to the sample, whereas earlier grown samples of CdSiP2 exposed to the same irradiance level damaged in 5 seconds or less. In that work, or in any other work to our knowledge, the samples were not exposed to millisecond or longer duration lasers at 1064 nm or 1550 nm. Because of the importance of CdSiP2 in nonlinear frequency conversion of lasers in the 1000 to 2000 nm spectral range, this study was performed to measure the damage thresholds at wavelengths in this spectral regime. Results of the damage threshold at different laser spot sizes will be presented.
μA 760 μm thick GaAs crystal was grown using HVPE. Transmission spectrum of this sample showed minimal
absorption for light having photon energy below the bandgap energy, indicating the absence of the EL2 defects
commonly found in Bridgman grown samples. Irradiance dependent absorption measured at 1.535 μm using
100 ns duration laser pulses showed increased nonlinear absorption in the HVPE grown GaAs compared to
Bridgman grown samples. The dominant nonlinear absorption process in both samples was absorption due to
free carriers generated by two-photon absorption. The HVPE grown sample showed higher nonlinear absorption
due to longer carrier lifetimes.