太赫兹涡旋激光特有的轨道角动量将为太赫兹无线通信和成像提供新的解决途径，但现有太赫兹激光器缺少激发和输出涡旋光的机制。本课题拟通过单片集成首次实现太赫兹矢量涡旋激光器。由分布反馈量子级联激光器（QCL）产生种子激光，由含增益及周期性双狭缝的谐振环作为涡旋光发射器，由波导连接QCL与谐振环并通过倏逝波耦合将种子激光转成环内单向传播的回音壁模式，进而利用布拉格衍射输出矢量涡旋激光。拟优化材料外延和微加工技术；发展表征涡旋光拓扑荷数与模式纯度的计算及测量方法；阐明太赫兹波在不同结构间传播与耦合的机制。进而操控倏逝波耦合系数、耦合长度与相位匹配，提高激光进入谐振环的效率与带宽。利用增益补偿谐振环损耗以获得均匀分布的回音壁模式，利用间隔为1/4波长的双狭缝促使反射波干涉相消从而确保回音壁模式单向传播，由此提高涡旋光的辐射效率与模式纯度。最终获得拓扑荷数可控、模式纯度与功率效率高的太赫兹矢量涡旋激光。

Quantized orbital angular momentum is a unique quality of terahertz vortex beam, which will provide new solutions for high capacitance terahertz wireless communication, high resolution terahertz imaging, etc. However, the mechanisms of exciting and radiating vortex beam are lack in the present configurations of terahertz lasers. This project aims to realize the first monolithically integrated terahertz semiconductor vortex laser. The device consists of a terahertz feedback quantum cascade laser (QCL), a ring resonator as the vortex beam emitter, and a transmission waveguide. The gain endowed ring resonator is featured with periodical dual-slits on the top surface. The single TM00 laser mode generated by the QCL is guided by the transmission waveguide and is injected into the ring resonator via evanescent wave coupling. This process transfers the TM00 mode into the whisperer gallery mode (WGM), which propagates uni-directionally along the ring resonator. Finally, the periodical dual-slits diffract the WGM into the free space, in form of a vector vortex beam. .In the basic stage, the technical improvements will be implemented for the high-quality material growth and precise device processing. Numerical calculations and experimental measurements will be developed to characterize the topological charge and the mode purity of the terahertz vortex beam. .As a further step, combining theoretical analyses and experiment results, we will explore the mechanisms of the terahertz wave propagation and coupling between the monolithically integrated structures. We then will manipulate the coupling coefficient, and coupling length and the conditions of phase matching of the evanescent wave coupling between the transmission waveguide and the ring resonator, in order to improve the coupling efficiency and bandwidth. .Mostly importantly, we will induce innovative device designs which are the core values of this project. Firstly, the gain material inside the ring resonator is pumped to balance the losses, and therefore to guarantee a uniform distribution of the WGM. Secondly, the interval of the dual-slits is set as a quarter of wavelength, which makes the reflected waves out-of-phase and hence significantly suppresses the reflectivity of the WGM. Such strategies will considerably improve the mode purity, the operation bandwidth, and the radiation efficiency of the terahertz vector vortex beam. .All these efforts will lead to the realization of semiconductor vortex lasers, generating terahertz vector vortex beam with controllable topological charge, high mode purity, and high radiation efficiency.