A theoretical and experimental investigation for wavelength switchable TmYAG laser modulated by Tm:YAG crystal length

• Performance of wavelength switchable LD side pumped rod Tm:YAG laser around 2 µm.
• The oscillating conditions are theoretically analyzed from the point of pump threshold with taking into account reabsorption loss.
• The laser oscillation at 2.02 µm with larger stimulated emission sections is suppressed by selecting appropriate Tm:YAG crystal length.
• Experimental results from single-module and two-modules Tm:YAG laser confirm the accuracy of the predictions obtained from the model.

Based on the analysis of the quasi-three-level side pumped Tm:YAG laser system, the oscillating conditions of this laser are predicted from the point of pump threshold. The laser oscillation at 2.02 µm with larger stimulated emission sections is suppressed when the crystal length is larger than ~85 mm with a 5% output coupling and then an efficient side-diode-pumped rod Tm:YAG laser operating at 2.07 µm is realized. Experimental results are reported from single-module and two-modules Tm:YAG laser and compared with the predictions obtained from the model. The experimental results show that the center wavelength of the Tm:YAG laser is shifted to 2.07 μm when the Tm:YAG crystal length is switched from 69 mm to 138 mm, which is in well agreement with the predictions obtained from the model.