Wide-Spectrum Mid-IR Generation by High-Powe Solid-State Lasers

对于“宽光谱中红外产生系统”，我们研究了具有非线性波长转换的高平均功率和高峰值功率固体激光器：(1)二极管泵浦固体激光器模型：将M^2概念应用于固体激光器优化。在Nd: YVO_4激光器中获得了58.6%的最大斜率效率。在此基础上，针对Yb: YAG微芯片和平板激光器对模型进行了改进。(2)高功率激光器的发展：我们开发了新的边缘泵浦方案，用于固体激光器的功率缩放。美国斯坦福德大学拜尔研究小组成功地实现了用于大功率系统的边缘泵浦之字形平板激光器。在Nd: YAG平板激光器中，我们获得了127 W的输出功率，斜率效率为57%。然而，Yb: YAG板的最大功率限制在40 W以下，坡度效率为20%。另一方面，对Taira组IMS进行了微芯片方案的研究。利用边缘泵浦Yb: YAG微芯片激光器结构，在准连续工作模式下获得了高达近100 W的输出功率和49%的斜率效率。(3)短脉冲产生：为了评估Yb: YAG作为超快激光器的潜力，我们测试了其可调性。利用400 μm的Yb: YAG微芯片，我们实现了Yb: YAG最宽的可调性，~ 85 nm，斜率效率高（60%），输出功率为3w。这一结果表明了利用Yb: YAG系统研制~ 100 fs （~ 15 fs）短脉冲激光器的可能性。(3)宽可调谐中红外产生：准相位匹配（QPM）方法将在波长转换领域开辟新的领域。为了改进新型QPM器件的极化方法，我们开发了原位极化系统，并在周期性极化的MgO: LiNbO_3中获得了宽带QPM芯片。此外，我们还与Byer教授和Fejer教授举行了小型会议，讨论了固态激光系统的当前技术和未来可能性。

Toward "Wide Spectrum Mid-IR Generation System" we have investigated in high average power and high peak power solid-state lasers with nonlinear wavelength conversion as following ; (1) Models for diode-pumped solid-state lasers : We applied M^2 concept to the solid-state laser optimization. The maximum slope efficiency of 58.6% was obtained in Nd : YVO_4 laser. Then we modified our model for Yb : YAG microchip and slab laser. (2) Development of high power lasers : We have developed new edge pumping scheme for power scaling in solid-state lasers. Byer group of Stan ford University has been demonstrated the edge pumped zig-zag slab laser for high-power system. In Nd : YAG slab laser we obtained 127 W output power with 57 % slope efficiency. However, the maximum power was limited below 40 W with 20 % slope efficiency in Yb : YAG slab. On the other hand, Taira group of IMS was investigated in the microchip scheme. Up to near 100 W output power with 49 % slope efficiency have been obtained in quasi-CW operation mode by edge pumped Yb : YAG microchip laser configuration. (3) Short pulse generation : In order to evaluate the potential of Yb : YAG as an ultra fast laser, we examined the tunability. With 400 μm Yb : YAG microchip we achieved the widest tunability, 〜85 nm, in Yb : YAG with high slope efficiency (60 %) and 3 W output power. This result indicates the possibility to develop under 〜100-fs (up to 〜15-fs) short pulse laser with Yb : YAG system. (3) Widely tunable mid-IR generation : The quasi-phase-matching (QPM) methods will open new horizons in the wavelength conversions fields. To improve poling methods for new QPM devices we developed in-situ poling system, then obtained a broad-band-QPM chip in periodically poled MgO : LiNbO_3. Additionally, we have held the small meeting with Prof. Byer and Prof. Fejer to discuss about the current technology and future possibility of the Solid-State Laser Systems.