Compact ultra-short pulse visible lasers

本文对铌酸锂波导准相位匹配（QPM）非线性光波长转换器件、稀土掺杂铌酸锂波导激光器和集成光栅大功率半导体激光器进行了研究。主要研究结果如下：1.大坂大学的一位研究人员访问了斯坦福大学，并获得了这些结果。(1)通过将相互作用长度增加到5.55 cm，在LiNbO 3波导QPM器件中实现了高达2800%/W的归一化SFG效率。该器件用于全光开关，并演示了低功率控制光开关。(2)研究了反向质子交换过程对导模的控制。结果表明，所制备的波导提供了更大的相互作用导模的重叠，提高了转换效率，建立了工艺仿真模型，并建立了仿真软件。2.为实现稀土铌酸锂波导激光器与QPM非线性光学波长转换器件的集成，建立了稀土掺杂铌酸锂QPM畴反转光栅的制作工艺。据发现，SiO2层抑制形成不需要的畴反转层在热处理稀土扩散掺杂。采用高压脉冲法在掺稀土晶体中成功地制作出了准相位调制光栅。研制了掺钕铌酸锂自倍频波导激光器。在814 nm泵浦下，获得了1084 nm的激光发射和542 nm的二次谐波绿色激光。

Research work on 1)LiNbO3 waveguide quasi-phase-matching (QPM) nonlinear-optic wavelength conversion devices, 2)rare-earth doped LiNbO3 waveguide lasers, and 3)high-power semiconductor lasers with integrated grating have been performed. Results are summarized as follows :1.A researcher of Osaka Univ. visited Stanford Univ. and obtained these results. (1) Normalized SFG efficiency as high as 2800%/W in LiNbO3 waveguide QPM devices was achieved by increasing the interaction length up to 5.55 cm. The device was used for all-optical switching, and switching by low-power control light was demonstrated. (2) Reverse proton-exchange process was studied to control the guided modes. It is shown that the resultant waveguides provide larger overlap of the interacting guided modes and improve conversion efficiency The process simulation model was built and a simulator was constructed.2.Fabrication technique of domain-inverted grating for QPM in rare-earth doped LiNbO3 was established for integration of rare-earth LiNbO3 waveguide laser and QPM nonlinear optic wavelength conversion elements. It was found that a SiO2 layer suppresses formation of unwanted domain-inverted layer during thermal treatment for rare earth diffusion doping. QPM gratings were successfully fabricated in the resultant rare-earth doped crystal by applying high voltage pulse. A self frequency doubling waveguide laser was fabricated in Nd-diffused LiNbO3. Pumped by a beam at 814 nm wavelength, the laser emission at 1084 nm and the intra-cavity second harmonic green wave at 542 nm was obtained.