Study On Frequency Converting Technologies On High-power Hundred-nanosecond Laser

High-power solid-state laser with narrow width has a quite widely spread usage for its high powe and high intensity. Compressing laser pulse width by Stimulated Brillouin Scattering(SBS) could furtherly rise pulse intensity while keeping preferable pulse quality and single-mode output, and therefore keeps a unique position in the aspect of ultrashort laser. As a key module to most laser devices, frequency convertion module could convert the wavelength of output laser pulse from near-infrared till visible light and even ultraviolet wave range, so that the usage of laser devices can be more widely spread. Therefore, combining frequency convertion with SBS compressing may exploit the advantages of SBS compressing technique. However, SBS compressed pulses are with traits of high energy and high intensity, and thus rigidly restrict the choosing of non-linear crystals for frequency convertion. This thesis studies, simulates and optimizes the scheme of high-efficiency Second Harmonic Generation(SHG) and Third Harmonic Generation(THG) aiming at high power hundred-picosecond laser device. On this basis, high-efficiency SHG and THG schemes are achieved and highly efficient SHG and THG output is obtaind by experiment.First, scheme designing, analyzing and comparisons are made with common non-linear crystals based on derivating and analyzing physical models of SHG and THG combined with crystal optics theories, in order to select the proper scheme.Then, write simulating programmes for SHG based on theoretical analysis, and validate the correctness of the programmes by comparing simulating results to those in literatures. Simulate SHG processes with different non-linear crystals to provide high-efficiency SHG scheme. LBO crystal with type-I phasematching is chosen and a high SHG efficiency up to 73.9% is achieved under continuous operation, and thus high-efficiency SHG process is gained. Meanwhile, the correctness of simulating programmes is proved again by experimental data.Finally, programmes for THG is modified from those for SHG above, and the correctness is validated with comparison to results in literatures. LBO crystal is chosen for high-efficiency THG process, of which the scheme is designed and provided. The efficiency of THG reached 34.2% at the top with continuous operation by experiment and therefore high-efficiency THG process is achieved.