Some optical properties of Cr 4+-doped crystals Academic Article uri icon

abstract

  • We summarize briefly some of our past studies, and report of preliminary recent new results concerning the optical properties of Cr 4+ -doped crystals that are important for utilization as passive Q-switching devices in Nd:YAG laser systems. The host crystals involved are YAG, YSGG, GGG, LuAG and forsterite. Excited-state lifetimes of 4.0, 1.0 and 1.7 μs were measured by the Cr 4+ fluorescence decay (1.3–1.7 μm) following pulsed excitation at 1064 nm in YAG, YSGG and GGG, respectively. The ground- and excited-state absorption (ESA) cross-sections at λ =1064 nm were estimated from transmission saturation measurements. For [Cr 4+ ,Mg 2+ ]:YAG the respective results were σ gs =(3.25±0.15)×10 −18 cm 2 and σ es =(6.25±0.5)×10 −19 cm 2 . In the orthorhombic forsterite, the cross-sections were polarization dependent. We got σ gs −19 cm 2 for E ‖ a , σ gs =(23±2)×10 −19 cm 2 and σ es =(9.0±0.7)×10 −19 cm 2 for E ‖ b , and σ gs =(16±1)×10 −19 cm 2 and σ es =(5.7±0.4)×10 −19 cm 2 for E ‖ c . Polarised ESA spectra were measured between 680 and 960 nm using the pulsed pump/probe technique. At 750 nm we got σ gs =(110±10)×10 −19 cm 2 and σ es =(25±3)×10 −19 cm 2 for E ‖ b . Passive Q-switching performance of a flashlamp-pumped Nd:YAG laser using an intracavity [Cr 4+ ,Ca 2+ ]:GGG sample is also demonstrated.

publication date

  • January 1, 1999