Study Of All Solid-State Tunable Blue Laser Pumped By Laser Diode

Summarrizing the development of laser technique in recent years, the importance and development of tunable blue laser are discussed. The principles of laser frequency transformation and the theory of phase matching in nonlinear optic crystals are also discussed. Based on this theory, angle of phase match is calculated. Pumping modes and the advantages of LD pump are analysed. Physical and chemic properties of CnLiSAF aresummed up. The characteristic of KN crystal is analyzed. At normal temperature, KN crystal can obtain noncritical phase match of 90C at wavelength of 857nm. According to its noncritical phase matching character, KN crystal can be used to get tunable blue laser output if cooperating with CrrLiSAF through changing it's temperature. The thermal effect of the working substance during the laser output in all solid state lasers and the common calculation methods of temperature distribution are mainly studied. The phase mismatch of base wave caused by temperature grads is also discussed. Model of temperature gradient in nonlinear optical crystals during frequency doubling is established. The temperature gradient in KN crystal and the phase mismatch caused by it are calculated. The efficiency change in frequency doubling of original wave is also studied. The mode of harmonic wave is expressed by power curves. Conclusion can be drawn that the frequency doubling efficiency is very low because of the phase mismatch caused by temperature changing. When cooling conditions, power of the base wave,or center of the crystal and that of the beam is detached, the inner temperature gradient of the crystal is also calculated. Conclusions can be drawn that the inner temperature gradient various with the situations and the frequency doubling efficient caused by it also differs. And, the energy distribution of double frequency output changes at the same time.