Comparison between S/1 and R/1 tests and damage density vs. fluence (ρ(Φ)) results for unconditioned and sub-nanosecond laser-conditioned KD2PO4 crystals

We present S/1 and R/1 test results on unconditioned and 355 nm (3ω), 500 ps laser conditioned DKDP. We find up to ~2.5X improvement in fluence in the S/1 performance after 3ω, 500 ps conditioning to 5 J/cm2. For the first time, we observe a shift to higher fluences in the R/1 results for DKDP at 3ω, 7 ns due to 500 ps laser conditioning. The S/1 results are compared to ρ(Φ) results previously measured on the same DKDP crystal [1]. A consistent behavior in fluence was found between the S/1 and ρ(Φ) results for unconditioned and 500 ps conditioned DKDP. We were successful at using Poisson statistics to derive a connection between the S/1 and ρ(Φ) results that could be tested with our data sets by trying to predict the shape of the ρ(Φ) curve. The value for the power dependence on fluence of ρ(Φ) derived from the S/1 data was ~11 ± 50%. The results presented and discussed here imply a strong correlation between the damage probability (S/1) test and ρ(Φ). We find a consistent description of the two test types in terms of a power law ρ(Φ) and that this basic shape held for all cases, i.e. the shape was invariant between unconditioned and conditioned results.