Research On Multiple-Wavelength All-Solid-State Lasers Based On Optical Superlattice

In the past several decades, solid-state lasers and nonlinear optical frequency conversion techniques have been widely used and achieved great progresses. Quasi-phase-matched (QPM) is an important part in the field of nonlinear optical frequency conversion, and it attracts more attention due to the advantages of compact structure, high efficiency, and flexible design. In this thesis, based on the optical superlattice fabrication technique, all-solid-state laser technique, and different types of superlattices as nonlinear frequency converter, a compact yellow laser and red, green, blue laser are developed and femtosecond supercontinuum generation in lithium tantalate (LT) and periodically poled lithium tantalite (PPLT) is studied. The main contents are as follows:1. The poling technique at room temperature fabricating superlattice is introduced. Based on this technique, microcomputer collecting and controlling system to assistant poling is designed. The result demonstrates the quality of the superlattice fabricated by using this assistant poling technique is superior to that by traditional technique.2. A laser-diode side-pumped, three-mirror cavity,1064nm and 1319nm dual-wavelength Q-switched Nd:YAG laser is set up and used as the pump source. A periodically poled lithium tantalate (PPLT) is employed as the frequency converter. we obtain 506mW yellow laser by sum-frequency generation (SFG).3. A two-dimensional (2D) quasi-periodically poled lithium tantalate superlattice is designed and fabricated by using the general dual grid method. The 2D quasi-crystal can simultaneously realize three nonlinear processes:a collinear optical parametric generation (OPG) cascading two non-collinear frequency doubling. In the experiment,532nm green laser is used as the pump source, and two sets of red-blue light is obtained in a single pass set up by tuning the crystal temperature. Together with the residual pump green light, automatically prismatic red-green-blue (RGB) light is realized.4. Based on optical parametric oscillation (OPO) cascading sum-frequency generation,2W RGB is obtained by employing two plans of cascaded periodically poled stoichiometric lithium tatanlate (PPSLT) and commensurate dual-periodically poled lithium tatanlate (CDPPLT) as frequency converter. The first plan is:pumped by 532nm green laser, using lmm thick,40mm long cascaded PPSLT, based on idler light OPO,2W RGB is obtained. The conversion efficiency from pump to 2W RGB is 36%, and luminous flux is 610lm. The second plan is pumped by 532nm green laser, using CDPPLT, based on idler light OPO,2W RGB is obtained, the conversion efficiency from pump to 2W RGB is 48%, and the luminous flux is 770lm.5. The femtosecond supercontinuum generation of Cerenkov radiation type in LT and PPLT is studied. When a femtosecond pulse laser with 800nm is incident on the LT crystal. The interaction of the powerful pulse laser and nonlinear crystal gives rise to self-trapped filament and femtosecond supercontinuum. The spectrum is broadened to a wide range from 490 to 970nm, and we also observe the conical emission of the supercontinuum. The theory of Cerenkov radiation is used to explain the conical emission. When PPLT is used as the nonlinear crystal, the spectrum can be further broadened from 380 to 970nm. The range of 380 to 440nm is generated from frequency doubling of pump light and 500 to 970nm results from supercontinuum generation.