In-band Pumping Of Nd-based All-solid-state Lasers And Its Application In Nonlinear Optical Frequency Conversion Technology

The in-band pumping could significantly diminish the quantum defect betweenthe pump photon and the laser photon, which is the main heat source in all-solid-statelasers, therefore decrease the waste heat, and thus release the thermal effectseffectively. However, the in-band pumping suffers the comparative poor pumpabsorption, which makes the high optical efficiency difficult. In this dissertation, theeffects of parameters of Nd3+-doped laser crystals on pump absorption and conversionefficiency are investigated in detail. By optimizing the crystal parameters, high opticalefficiencies are achieved with simple pump structure and laser cavity. On this basis,the in-band pumping is utilized in nonlinear optical frequency conversiontechnologies of intra-cavity singly resonant optical parametric oscillator (ICSRO) andself-Raman laser, the performances of which are sensitive to thermal effects. Thein-band pumped lasers show advantages in output power, conversion efficiency,power stability, and beam quality compared with those under808nm traditionalpumping. The main contents of this dissertation are as follows:1. By using880nm LD as pumping source, the optical efficiencies of1064nmand1342nm laser output power with respect to incident pump power reach60.0%and38.1%, respectively, which are higher than those under808nm pumping. The opticalefficiency of1064nm Nd:YAG laser under885nm pumping is53.8%, which is closeto that of54.3%under808nm pumping.2. By using914nm output of a Nd:YVO4laser as pumping source of Nd:YVO4laser, the slope efficiencies of1064nm and1342nm laser output with respect toabsorbed pump power reaches82.0%and65.4%, respectively. After optimizing thecrystal parameters, the optical efficiency of1064nm laser output exceeds50%, whichreaches a practical level and is the highest optical efficiency of Nd3+-doped lasersunder thermally boosted pumping from high Stark sublevel.3. A brand new pumping scheme of integrated pumping is proposed. Theapplication scope, evaluation method, and determination of the optimal pump powerproportion are discussed. Experimental research is carried out through an end-pumpedNd:YVO4laser which is pumped by808nm LD and880nm LD simultaneously. Theconceive and analysis of integrated pumping are verified preliminarily.4. By using880nm LD as pumping source of a Nd:YVO4-PPLN ICSRO, idleroutput with wavelength tuning range of3.66-4.22μm and maximum power of1.54W is obtained. Meanwhile, the power, efficiency, and stability are better than the ICSROunder808nm pumping. The influence of resonant signal wave output coupling on thethreshold and down-conversion efficiency of ICSRO is experimentally investigated.The experimental results agree with the theoretical expectations of optimizing theICSRO threshold by resonant signal wave output coupling thus keep a gooddown-conversion efficiency under high pump power.1.43W idler output at3.66μmand5.03W signal output at1.5μm are obtained simultaneously, corresponding to anextraction efficiency of30.2%, which is the highest efficiency of cw ICSRO everreported.5.880nm LD is used as pumping source of acoustic-optic Q-switchedNd:YVO4self-Raman lasers to alleviate the problems of Raman gain decreases withincreasing temperature and thermal lens effect limits the maximum pump powerallowed. The maximum average output power of1176nm,588m and1525nm are6.11W,5.28W and2.96W, respectively. The in-band pumped self-Raman lasers showobvious higher power and efficiency compared with those under808nm pumping.