Energy-transfer upconversion and thermal lensing in high-power end-pumped Nd:YLF laser crystals

Abstract

Thermal lensing in an end-pumped Nd:YLF rod, under lasing and non-lasing conditions, has been investigated. Under lasing conditions a weak thermal lens, with dioptric power varying linearly with pump power, was observed. Under non-lasing conditions where higher inversion densities are involved, hence relevant to Q-switched operation or operation as an amplifier, a much stronger thermal lens was measured, whose power increased non-linearly with pump power. This difference has been attributed to the increased heat deposition due to the subsequent multiphonon decay following various interionic upconversion processes, which increase strongly under non-lasing conditions, and is further exacerbated by the unfavourable temperature dependencies of heat conductivity and rate of change of refractive index with temperature. A strategy for reducing upconversion and its associated thermal loading, without degrading laser performance, is discussed.

More information

Identifiers

Catalogue record

Export record

Altmetrics