Tunable solid-state laser sources emitting in the 2 μm wavelength region are important for applications in atmospheric monitoring and laser radar because many molecular absorption lines are present there. We report on continuously tunable operation of a diode pumped Tm:YAP laser, which is among the most efficient laser materials emitting in the 1.9−2 μm spectral band, while continuous tuning of this material has not yet been reported. The 3mm long a-cut (Pbnm) crystal sample with 4% at. doping was used. The 400 μm fiber was used to deliver up to 17W of pump power to the coupling optics. The differential efficiency in respect to the absorbed pump power reached 57% while the attained optical-to-optical efficiency was 48%. The maximal output of 4.8W was only limited by the available pump power and relatively low sample absorption. The free running wavelength was measured at 1.99 μm. A 1.5mm thick birefringent plate made from quartz inserted under a Brewster's angle was used as a tuning element. The maximal output power of 3.85W in this set-up was obtained. The laser could be tuned from 1869nm up to 2036nm with a maximum at 1985 nm. The tuning range of over 160nm covers many important atmospheric absorption lines. In this wavelength range, the absorption depth in water changes from 100 μm (laser wavelength 1.94 μm) to 400 μm (wavelength 1.87 μm) making it potentially attractive for medical applications as a laser scalpel with variable cutting depth.

Date Published: 17 April 2006
PDF: 7 pages
Proc. SPIE 6190, Solid State Lasers and Amplifiers II, 619008 (17 April 2006); doi: 10.1117/12.662681

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