Stimulated emission cross section at various temperatures based on laser performance

Abstract

The determination of stimulated emission cross sections at various temperatures is reported. Neodymium doped yttrium orthovanadate crystal (Nd:YVO 4 ) was employed as a gain medium. The temperature of the crystal holder varied between 20 and 60 °C. The cross section was determined based on laser performance. The slope efficiency of the diode endpumped Nd:YVO 4 laser system decreased from 40.2% to 31.7%, while the threshold power increased from 0.744 to 1.028 W. The far-field beam diameter increased linearly with the absorbed pump power at a constant temperature. There was no correlation between the rate of change of the beam diameter with temperature due to mechanical stress fluctuation. The stimulated emission cross section was found to decrease at a rate of −0.45% °C−1 , which concurs with previous works. The stimulated emission cross section of various solid-state gain mediums can be determined through this method.

Passively Q-switched Nd:YVO4 laser operating at 914 nm

“…Using a linear fit, the stimulated-emission cross-section decreases with a negative slope of 9.8 × 10 −23 cm 2 K −1 . This is in good accordance to the temperature dependency observed by Krishnan et al25 (−1.39 × 10 −22 cm 2 • C −1 ), while taking different crystal doping concentrations and measurement techniques into account.…”

Anisotropic stimulated emission cross-section measurement in Nd:YVO 4

“…Thus, SE cross-section can be calculated via combining the overlap efficiency between mode beams and pump beams. [7,21] In these studies, the overlap efficiency is invariant because the propagating directions of laser is axial. However, the overlap efficiency is dependent on propagating directions in our study.…”

“…For example, several groups investigated the temperature dependence of SE cross-section on crystals. [3,6,7] For Yb-doped materials, the SE cross-section is dependent on doping concentration in highly doped cases. [8] SE cross-section also has strong relation with polarizations for anisotropic crystals, such as π polarization and σ polarization in uniaxial crystals [9][10][11] and x polarization, y polarization, z polarization for biaxial crystals.…”