| At present, LD (laser diode) end-pumped solid-state lasers (DPSSL) have become an important field of the research of solid state laser. And the blue laser has many applications. Now, the blue laser is mostly generated by LD or end-pumped intra-cavity frequency doubling of Nd:YAG laser at 946nm, Nd:YVO4 laser at 914nm and Nd:GdVO4 laser at 912nm . In this paper, we report a deep-blue laser at 456nm generation by intra-cavity second harmonic generation (SHG) of a continuous-wave laser operation of a Nd:GdVO4 laser at 912nm. Firstly, a model of end-pumped quasi-three-level 912nm Nd:GdVO4 laser is developed. At the same condition, the gain of 912nm is less than the gain of 1063nm and 1341nm. According to the model, the highly efficient four-level transition of 1063nm and 1341nm should be suppressed in order to generate the 912nm laser. And what's more, a short Nd:GdVO4 crystal with low neodymium concentration is needed if we want to realize the CW operation of 912nm laser at room temperature.At room temperature, we successfully create an Nd:GdVO4 laser with 2.1W output power at 912nm which employs the shot Nd:GdVO4 with low concentration of Nd3+. Furthermore, intra-cavity SHG with a LBO crystal into the deep-blue spectral range at 456nm was achieved with 2mW output power. Secondly, we find that the flat-concave cavity is less sensitive to thermal-lensing effect and maladjustment of mirrors than the flat-flat cavity. And the output power, the slope efficiency and the threshold power of the laser with the flat-concave cavity are little changed when the length of cavity is changed. So the flat-concave cavity is better than the flat-flat cavity with the CW Nd:GdVO4 laser at 912nm. Finally, we find that the request of controlling temperature of the laser crystal is not rigor.Soon, the deep-blue light at 456nm with higher output power will be demonstrated by intra-cavity SHG of Nd:GdVO4 laser at 912nm based on the work in this paper. |
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