Tunable mid-infrared laser radiation sources are of interest for many applications in spectroscopy, ranging, remote-sensing, medical diagnosis and treatment and also for pumping nonlinear (OPO) and laser materials. The ZnSe:Cr²⁺ is a promising laser active material for lasing in the range of 2-3 μm. Up to now number of sources have been used for pumping ZnSe:Cr²⁺ active medium: Er-fibre laser, color-center laser, Co:MgF₂ laser, Tm lasers, and Raman-shifted Nd:YAG laser [1-4]. In our study we have demonstrated, characterized and compared ZnSe:Cr²⁺ laser coherently pumped either by flashlamp-pumped Er:YAP (wavelength 1.66 μm) or diode pumped Tm:YAP (wavelength 1.97 μm) laser radiations. For the case of ZnSe:Cr²⁺ laser pumping by wavelength 1.66 μm, the Er:YAP laser was constructed. From the measured output radiation characteristics followed that the maximal ZnSe:Cr ²⁺ laser output pulse energy was 5.5 mJ (slope efficiency 23%), and the length of pulse 120-160 μs. With the help of dispersive prism inside the resonator, the generated laser radiation was tunable from 2100 nm to 2450 nm with only 2 times drop in laser efficiency. The temporal profile and spatial structure of the generated laser beam were measured. Consequently, the diode-pumped Tm:YAP laser was constructed for coherently pumped ZnSe:Cr²⁺ laser. LIMO laser diode (40 W) was used for longitudinal pumping of Tm:YAP laser. The output characteristics and tuning curves were measured for various ZnSe:Cr²⁺ laser resonator arrangements and also for various pumping radiation conditions in pulsed regime (pulse duration, repetition rate, duty cycle). The maximal obtained ZnSe:Cr²⁺ laser output pulse energy was 0.35 mJ for the Tm:YAP pump pulse energy 13.5 mJ (pulse radiation 5 ms, repetition rate 20 Hz). The generated laser radiation was tunable from 2100 nm to 2450 nm. The temporal profile and spatial structure of the generated laser beam were measured.

Date Published: 17 April 2006
PDF: 8 pages
Proc. SPIE 6190, Solid State Lasers and Amplifiers II, 61901F (17 April 2006); doi: 10.1117/12.684127

Published in SPIE Proceedings Vol. 6190:
Solid State Lasers and Amplifiers II
Alphan Sennaroglu, Editor(s)