We study the excitation of luminescence, photoionization, and
laser-induced breakdown in a multi-component silicate
photo-thermo-refractive (PTR) glass, and in fused silica. PTR glass is a high-purity homogeneous photosensitive alkalisilicate
glass with intrinsic absorption edge at 5.8 eV (214 nm). Experiments are conducted with ultrashort laser pulses
(100 fsec< τ < 1.5 psec) at the wavelengths 780 nm, 1430 nm, and 1550 nm. Filaments are observed inside both glasses
and explained by a balance between Kerr self-focusing and free electron defocusing. Keldysh theory is used to model the
formation of filaments and values of about 10<sup>13</sup> W/cm<sup>2</sup> for laser intensity and 10<sup>19</sup> cm<sup>-3</sup> for free-electron density are
estimated. Laser-induced damage by pulses at 1430 nm and 1550 nm is detected in fused silica and PTR glass by third
harmonic generation due to the formation of an interface between a damage site and the surrounding glass matrix. It is
found that there is an intensity range where luminescence and photoionization in both glasses occurs without laserinduced
Three conditions for non-collinear third harmonic generation by a PTR glass volume Bragg grating are demonstrated
using infrared femtosecond pulse illumination. Each condition corresponds to a different angle of grating orientation.
We identify the angles as corresponding to Bragg diffraction at ω, Bragg diffraction at 3ω, and a non resonant Bragg
angle involving three ω photons interacting with a nonlinear grating vector. The generation of non-collinear third
harmonic at each of these angles is modeled with wavevector interactions. Theoretical predictions from the wavevector
equations are obtained and compared to experimental measurements. We discuss the nonlinear grating in the PTR glass
grating as resulting from modulation in the nonlinear refractive index of PTR glass.
It was found that high purity soda lime glass shows a markedly different induced absorption spectra when exposed to different types of ionizing radiation such as UV lamp or femtosecond and nanosecond laser pulses. The following irradiation was used in the experiments: nanosecond pulses at the fundamental and harmonics of a Nd:YAG laser (λ = 1064, 532, 355, and 266 nm), femtosecond pulses of a Ti:sapphire laser operating at λ = 780 nm, ultraviolet rays from a high pressure Xe lamp, X-rays, and Gamma rays. Features of radiation defect generations are discussed.