Investigation Of The Thermal Effects In LD Pumped Er, Yb:YAB Laser

Compared with the other lasers, the1.5μm laser has many advantages such as low transmission loss and safe for human eye etc, so it has many applications such as optical fiber communication, quantum information transfer, national defense, military and medical. So1.5μm laser attract scientists of great concern. At present,1.5μm laser have Raman lasers, fiber lasers, optical parametric oscillator method and solid-state lasers.With the further development of scientific research, experimental study of quantum optics and quantum information demand a lower noise, better stability single-frequency laser. The laser used in our present experimentlight is a fiber laser and OPO laser, the fiber laser has high quantum noise and the OPO laser has bad stability. Compared with other methods, the LD end-pumped solid state lasers have low noise and good stability. Therefore, our aim of experiment is to obtain a low noise and good stability single-frequency laser with Er,Yb:YAB crystal.Compared with Nd:YVO4and Nd: YAG crystal, Er,Yb:YAB has worse thermal properties, and the thermal effect is very serious. So, how to reduce the thermal effects is the major difficulties in our experiments.In experiments, we carried out a detailed analysis of thermal effects, a maximum TEMoo output power of290mW was obtained at the LD pump power of5W. We carried out a series of research results as follows:(1) A detailed analysis of the reasons of the heat deposition of solid-state laser have been done, we analyzed the thermal-induced diffraction losses, thermal lensing, thermal-induced birefringence and thermal depolarization, we also learned some measures to overcome and compensate these thermal effects.(2) We simulated the internal temperature distribution of the laser crystal with finite element analysis software under different experimental conditions. While the pump light is focused to the front surface of the crystal, the maximum temperature of crystal is810℃, while it was focused to100μm of the crystal, the temperature is811.7℃, while focus to the center of crystal and the back surface, the highest temperature are581.7℃and377℃respectively. In our experimental, the heat flux along vertical in the crystal mainly depends on air convection of the crystal face, we simulated the internal temperature distribution while air convection was considered and does not consider the air convection, we found that the face air convection have almost no effect to the temperature distribution of the crystal. Which means that very less heat flow along the vertical, so, the radial temperature gradient inside crystal is very large, which is one aspect reason of thermal effects.(3) The thermal focal length of Er,Yb:YAB crystal was measured by using the knife method. When the pump source was continuously operated, under5W pumping, the thermal focal length of the crystal was only10mm.(4) We have designed a two-mirror cavity, a maximum continuous TEM00output power of290mW was obtained at the LD pump power of4.95W with the slop conversion efficiency of8.5%.