Theoretical And Experimental Studies On 1123 Nm Nd:YAG Ceramic Lasers

Diode pumped solid state laser (DPSSL) has the advantages of simple structure, small volume, high conversion efficiency, high reliability, long life time, and good quality of output beam. In addition, DPSSL can combine the laser operation with nonlinear optical frequency conversion. DPSSL has been widely used in many fields, such as optical storage, optical interconnection, space communication, light information processing, laser manufacturing, medical care and military field. Now DPSSL is one of the most promising laser sources and becomes a main research and development direction in laser technology.Researchers focus on the transparent ceramics in the DPSSL, because of their short manufacturing period, lower manufacturing costs, the possibility of high doping concentrations and big size. As a typical representation of the transparent ceramics, Nd:YAG ceramic has the advantages of high gain, low threshold, and excellent thermal properties, it has become the most widely used ceramic in DPSSL.In recent years, Nd:YAG ceramic lasers operating 1064 nm,946 nm or 1318 nm have been reported.1123 nm line can be used as a pump source for Thulium upconversion fiber lasers to generate blue light emission. And yellow-green light laser at 561 nm which has important applications in biology and biomedicine can be obtained from the frequency-doubled 1123 nm line. Therefore, lasers operating at 1123 nm attract much attention.In this paper, by using Nd:YAG ceramic as the gain midium, we study the LD end pumping 1123 nm continuous wave (CW), actively Q-switched and passively Q-switched lasers experimentally. Also, we study the actively Q-switched and passively Q-switched lasers theoretically. The main contents are as follows:1. LD end pumped continuous wave lasers operating at 1123 nm are investigated using two different output mirrors. Also we investigate the continuous wave lasers operating at 1123 nm when the cavitie lengths are different. 2. LD end pumped actively Q-switched 1123 nm Nd:YAG ceramic laser is obtained for the first time. When the incident pump power is 17.1 W and the pulse repetition is 20 kHz, an average output power of 5.84 W is obtained.3. LD end pumped passively Q-switched 1123 nm Nd:YAG ceramic laser is obtained for the first time. Cr:YAG with initial transmission of 94% is used as passive saturable absorber.4. The four level actively Q-switched lasers are analyzed theoretically when the spacial distributions of the intracavity photon density and the population inversion density are considered. And we do the theoretical calculation by taking the experiment as an example. Then the theoretical results and experimental results are compared.5. The four level passively Q-switched lasers are analyzed theoretically when the spacial distributions of the intracavity photon density and the population inversion density are considered. And we do the theoretical calculation by taking the experiment as an example. Then the theoretical results and experimental results are compared.