J. H. Bechtel

Normalization technique for accurate measurements of two‐photon absorption coefficients

A new technique for accurate measurement of the two‐photon absorption (TPA) coefficient relative to the known TPA coefficient of a reference material is presented. It is shown that the ratio between the transmitted energies of two identical laser pulses through the unknown and the reference materials is a constant which is independent of the laser intensity if a filter of an appropriate transmission value F is put in front of the reference material. The ratio between the two TPA coefficients is simply related to F. Using the outlined technique the ratios between the TPA coefficients of three semiconductor samples were measured with an accuracy of ±10%

Laser‐induced breakdown and nonlinear refractive index measurements in phosphate glasses, lanthanum beryllate, and Al2O3

We present results of measurements of the laser‐induced dielectric breakdown threshold in two phosphate composition laser glasses, in lanthanum beryllate:Nd, and in Al2O3. The nonlinear refractive indices for these materials are also presented. The measurements were made with single 30‐psec 1.064‐μm pulses. The results are compared with those for other laser materials in the 1.06‐μm spectral region.

Picosecond laser-induced damage morphology: Spatially resolved microscopic plasma sites

Abstract The morphology just above threshold of damage sites caused by picosecond 1.06 μm laser pulses is shown to consist of a collection of micron-sized, spatially distinct vestiges of individual plasmas. From the observed site density, the density of electrons which may initiate breakdown can be inferred. The morphology is consistent with an avalanche ionization model, but not with absorbing inclusion damage.

Picosecond Laser-Induced Damage in Transparent Media

A high degree of transparency is a material characteristic of great importance for all laser systems. For high-power systems, that characteristic becomes a vital requirement of many solid components.