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Study on laser-induced damage characteristics of optical gain material

Laser amplification is one of the key links to achieve high-power laser output. With the increasing of the energy inside the gain material, the damage properties of the material become the primary issues for the power improving. In this paper, the optical field amplification characteristic of Neodymium glass (Nd:glass) is investigated under the high gain condition. A theoretical analysis model of field damage properties is established. The light field distribution inside the material is calculated by using the fast Fourier transform algorithm. Based on the electron proliferation theory, the changes of impact ionization rate and multi-photon ionization rate inside the material are studied. Finally, the change law of damage threshold with laser pulse width and optical field is analyzed. Results show that as the optical field increases, the onset position that the damage occurs should forward lead progressively in the material. Especially, when the incident optical field is 109 V/m, the damage position of the material occurs at 32mm from the incident plane.