Ld Pumped Solid-state Blue Laser Research

LD-pumped all-solid-state laser is a hot field in current solid state laser research. LD-pumped all-solid-state green laser is relative mature and it is not rare to find green laser with output power above 1W. However, few all-solid-state blue lasers could be found in market because of its low output power, which confines its application. For this technical difficulty in all-solid-state blue laser, we join the research line, hoping to present some useful exploration.Considering the industrialization, we choose the Nd:YAG laser crystal, which is hopeful to give relatively high output power of 473nm blue laser through frequency-doubling technique. The quasi-three-level transition would be used in our experiment, so we analyze the theory of quasi-three-level, accurately, the quasi-three-level transition of Nd³⁺. We derived the equation of threshold pump power, the distribution function of laser field and some other items that related with laser resonating, all of these might give us some helpful conclusions in aid of the laser resonator design.Attributes of three nonlinear crystals, BBO, LBO and BIBO, have been summarized. Their optical parameters related to frequency-doubling efficiency were presented and compared. Here we emphasized the BIBO crystal. The angle-deviation, temperature-deviation and wavelength-deviation also were calculated and analyzed. We plan to use folding cavity in our experiment, so we employed the ABCD theory to calculate the Gauss laser beam characters in equivalent G-parameter cavity. As heat effect exists, some laser beam parameters were derived for multi-element cavity with a thermal lens within. In addition, a common method for astigmatic compensation was introduced when allow for folding cavity's astigmation.Finally, we set up a V-type resonator for introcavity frequency-doubling blue laser experiment according to the above quasi-three-level theories as well as analysis and comparison of necessary apparatus. In the experiment, we obtained 154mW 473nm blue laser. By use of computer, we calculated'and plotted the laser beam parameters curves versus thermal lens with astigmation taken into account. Also, someexploratory tests have been carried out to find the reason for low output power of blue laser and its poor laser beam quality, after that, we presented the possible explanation.