Research on high efficiency ceramic laser

探索优秀的激光材料并应用于研发新型激光器件始终是激光研究的发展方向。近年来迅速发展的新型陶瓷是继单晶、玻璃之后又一值得瞩目的优秀激光材料。随着制备工艺的突破性进展，多晶纳米陶瓷作为激光增益介质不仅具有与单晶相比拟的光学质量、良好的化学稳定性、优秀的物理、机械性能和光谱、激光特性，而且具有显著的制备优势:（1）易于制备，成本低、周期短，能够规模化批量生产；（2）可获得光学均匀性良好的大尺寸和高掺杂；（3）能够制备各种形状的多层和多功能结构。这些优点给予了高性能固体激光器前所未有的高性/价比和能够满足各种应用要求的灵活设计优势，使得长期以来光学工程师希望按照特定激光性能要求来进行材料分子设计以获取合适激光材料的梦想即将成为现实。透明激光陶瓷有望成为新的优秀激光材料引领未来固体激光工程发展的革新性飞跃！ 目前国际国内对激光陶瓷的研究方兴未艾，很多研究小组都在致力于各类激光陶瓷材料和陶瓷激光器件的研究。本课题基于这种新兴材料开展了一系列高效率激光特性探索。主要研究内容如下： 1、 Nd：YAG激光器是世界上使用最广泛的固体激光器，目前其主要工作物质为Nd：YAG单晶。新型Nd：YAG激光陶瓷具有和单晶相媲美的优秀性能。对Nd：YAG陶瓷激光器的开发具有广泛的应用空间和可观的经济效益！我们采用自主设计的九条LDA阵列侧向均匀泵浦系统，验证了高效率Nd：YAG陶瓷激光器，获得236W准连续输出，斜率效率62％，是目前国际上同种材料报导的最优效率；进而进行电光调Q实验，在100 Hz调制频率下获得脉冲宽度10ns，脉冲能量50 mJ，最大峰值功率5 MW的脉冲输出；在此基础上进行倍频实验，获得平均功率为3W的绿光输出。 2、 新型Yb:Y2O3陶瓷具有比Yb:YAG单晶更优秀的热机械特性，宽发射带宽，具有作为高平均功率飞秒激光器、宽带调谐激光器以及超大功率高光束质量薄片激光器的潜质。我们采用CAMIL结构LD端面泵浦双程吸收的谐振腔设计，在Yb3+:Y2O3薄片陶瓷中获得10.5W连续激光输出，斜率效率37.5%，优于此前国际上同种材料报导的最高输出功率。With the breakthrough of the fabrication technology, high quality transparent ceramic media with much low scattering losses have been made. The novel laser ceramic contains not only good thermal, mechanical and spectra properties as fine as single crystal but also can be made with large size and high concentration. Further more, mass manufacture is possible. It is a potential excellent laser media for promoting the development of future’s solid state laser engineering. In this paper, we designed a quite uniformly nine-stacks side-around arranged compact pumping system and thus demonstrated a high efficiency high power quasi-CW laser with a Nd:YAG ceramic rod. With 450 W quasi-CW stacked laser diode bars pumping at 1064 nm, 236 W optimum output laser at 1064 nm was obtained. The optical-to-optical conversion efficiency was 52.5% and corresponding slope efficiency was 62%. With 420 W quasi-CW LDA pumping at 808 nm and 100 Hz modulating repetition rate, 50 mJ output energy at 1064 nm was obtained with 10 ns pulse width, 5 W average output power and 5 MW peak power. Its corresponding slope-efficiency was 29.8%. With KTP nonlinear optical crystal, 3 W green laser was obtained. Yb：Y2O3 ceramic is an ideal laser material, it has the excellent physical and chemical properties and spectra characteristics as well as Yb:YAG single crystal. Further more, its thermal conductivity and emission bandwidths are nearly twice of those of Yb:YAG, which is very promising candidate in high power and numerous femto-second pulse laser application fields. With the compact active mirror laser (CAMIL) design, a Yb：Y2O3 ceramic has been demonstrated at room temperature. An optimum output power of 10.5 W has been obtained under the max pumping power of 35 W. Its corresponding slope efficiency was 37.5%. The laser wavelength red-shift phenomena have been observed with the increasing of the pump power and the change of the reflectivities of output coupler (ROC)