Excited state absorption of pump and laser radiations in NYAB non-linear crystal operating at 1.3 µm for visible laser light generation

¹ Departamento de Física de Materiales, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid, Spain
² Laboratoire de Physico-Chimie des Matériaux Luminiscents (UMR CNRS 5620), Université Claude Bernard-Lyon, 69629 Villeurbane, France
³ Fujian Institute of Research on The Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P.R. China

Corresponding author: Jose.Garcia_Sole@uam.es

Received: 20 September 1999
Revised: 19 January 2000
Accepted: 14 February 2000
Published online: 15 April 2000

Abstract

Excited state absorption of laser (≅ 1.3 µm, corresponding to the laser channel) and pump (790-860 nm) radiation have been investigated in Nd doped YAl₃(BO₃)₄ non-linear laser crystal. Laser gain slope efficiency measurements as a function of pump wavelength have been used to estimate the excited state absorption of pump radiation. On the other hand, excited state absorption cross-section in the 1300−1400 nm wavelength range has been measured by using two beam spectroscopy. We have obtained that excited state absorption cross-section for pump radiation is negligible whereas around 1.3 µm it is comparable to the stimulated emission cross-section from ⁴F_3/2 state, so that the net gain cross-section becomes negative for certain wavelengths.