基于多波导结构的大功率高亮度半导体激光的机理研究

Semiconductor lasers with both large power and high brightness are widely used in the fields of national defense, laser processing, medical care, pumping source and so on. Currently, the most available way for such lasers is based on the main oscillators’ (MO) power amplifiers (PA). MO are basically ridged waveguides with narrow ridges, for generating seed photons with high quality. PA are basically tapered waveguides for the seed photons power amplification. However, higher orders of optical modes would laser out to reduce the beam quality as well as the optical brightness when power had gone up even larger. In view of the above problem, based on researching the multiple optical waveguides coupling mechanism, this topic proposes an innovated multiple optical waveguide laser structure: multiple MO and PA are connected by photonic crystal waveguides. In this structure, every waveguide element assures an independent parameter of the final output laser. The whole laser cavity assures all the waveguide elements couple together. Photonic crystal waveguides can assure power transmission with almost no wastage. Multiple MO and PA assure beam quality and power amplification at a higher level. By inducing this optical system, we are considering the physics mechanism of multiple otical waveguide laser structure, aiming at an international level 10W output laser single emitter at 980nm wavelength. The M2 factor shall be <3. The vertical and horizontal divergence shall be smaller than 5° and 35° accordingly. The brightness shall be larger than 500MW•cm-2•sr-1. This topic brings new concepts for semiconductor laser designing.

大功率高亮度激光广泛应用于国防、激光加工、医疗、泵浦等领域，目前获得此类激光最有效的方法是主控振荡器(MO)的功率放大(PA)，MO多采用窄条宽的脊形波导产生高质量的种子光，锥形波导可实现种子光的PA，然而在进一步提高功率时会引起高阶模激射，降低了光束质量，亮度随之下降。针对以上问题，本课题创新性的提出，深入研究光学系统中多波导耦合机理，利用光子晶体波导连接多个MO和PA构成组成多波导激光结构，实现大功率高亮度的半导体激光。此结构中，每个波导单元发挥各自的独特作用，再通过谐振腔耦合成一个整体：光子晶体波导可几乎无损耗的传递能量；多个MO和PA可保证光束质量并进一步放大激光功率。本项目拟研究多波导激光结构的物理本质，实现国际水平980nm激光单管输出功率>10W，M2因子<3，垂直和水平发散角分别<5°和35°，亮度>500MW•cm-2•sr-1，为激光器的研发提供新的思路。

大功率高亮度激光广泛应用于国防、激光加工、医疗、泵浦等领域，本项目在执行期间，圆满完成任务书规定的所有研究任务和研究指标，取得了较好的科研成果，项目结束实现 Y形波导分束器能量传输效率每个分支超过47.95%，弯曲波导总体能量传输效率超过95.9%，转弯半径在20μm；980nm波段激光单管输出功率12W，M2因子1.85，慢轴和快轴发散角分别为5.0°和18.2°（半角），双锥形激光器脊型区域的亮度达到755.5MW•cm-2•sr-1，圆满完成任务指标，研制了一套适用于在脊形波导下的台面上制备光栅/光子晶体的工艺流程； 本项目结题时，实现发表文章11篇，其中SCI文章5篇，其中标注本基金的文章6篇，包括SCI文章4篇，申请专利8项授权2项，另有3项专利授权，协助培养硕士生2名，均圆满甚至超额完成任务书指标。项目成果目前应用于泵浦光纤激光器和固体激光器，由于其较高的功率、光束质量和亮度，使得光纤激光器的泵浦效率较高。