中红外超快激光在医疗、遥感、军事和科研等领域具有重要的应用前景。然而采用光参量振荡、差频、参量放大等非线性方法获得此波段的超快激光具有结构较为复杂的缺点。因此，本项目提出LD泵浦新型Er3+掺黄长石结构ABC3O7晶体直接实现3.0μm超快激光的方法。该体系的低声子能量(约560cm-1)和局部无序结构使Er3+的吸收和荧光光谱有显著展宽，非常有利于产生锁模超快激光。另外，该体系还具有热导率高、机械强度大及较易获得大尺寸优质单晶等优点。本项目从组成设计出发，从体系中筛选出2~3种ABC3O7晶型并调控Er3+及共掺敏化离子浓度，研究晶体生长工艺、光谱和激光性能，重点是通过混晶多格位调控和共掺敏化离子能级耦合的理论及实验研究，使谱线进一步非均匀展宽，优化出1~2种Er: ABC3O7晶体进行LD泵浦、被动锁模研究，实现高效率、窄脉宽、稳定运转的3.0μm超快激光输出，为其进一步应用奠定基础。

Mid-infrared wavelength ultrafast laser has found important potential applications in the fields of medicine, dectection, national defense and fundamental science researches etc.,which is the hot topic in the past decades, now it is just beginning to thrive in China. Nonlinear optical conversion techniques including OPO, difference frequency and OPA are the main methods to realize mid-infrared ultrafast laser currently. But as we know these optics system are very complicated, therefore,we bring forward to LD pump on one kind of novel Er3+:ABC3O7 (A=Ca,Sr,Ba; B=Y, La,Gd; C=Ga,Al) Melilite crystals to achieve 3.0 micron ultrafast laser directly. They have low phonon energy (around 560cm-1) and highly disordered structure, as a result the absorption and emission spetra of the active ion Er3+ inside are broadened extremely, which is very favorable for generation of the mode-locked ultrafast laser. In addition,they have high thermal conductivity,and high mechanical strength etc, and large-sized crystals with high optical quality can be grown by Czochralski technique. All these factors make Er3+:ABC3O7 crystals excellent candidates for 3.0μm ultrafast laser. In this project, we will design the crystal structure and elements,to target on 2~3 kinds ABC3O7 crystals and adjust Er3+ and the co-dopant sensitizing ions concentrations,then explore the crystal growth technique to obtain high-quality Er:ABC3O7 crystals, next study their spetral and laser characterizations.The emphasis is focused on study of the adjustment of the multi-locations in the hybrid crystals and the co-dopant sensitization ions through energy levels coupling theorically and experimentally, in order to further broaden their absorption and emission spectral width inhomogeneously. Finally,1~2 kinds of optimized Er:ABC3O7 crystals are obtained to carry on LD pumping and passive mode-locking with the excellent saturable absorber mirrors such as graphene and carbon nanotube, finally achieve high efficiency, short pulse and stable 3.0 micron ultrafast laser, for providing foundation for their application in mid-infrared ultrafast laser.