研究了渐变型空芯波导(GTHW)在太赫兹波段的传输特性。基于几何光学方法, 仿真分析了波导的输出光束质量和传输损耗特性。相比均匀型空芯波导, 当光从渐变型空芯波导的大端传输至小端或沿相反方向传输时, 渐变型波导具有特殊性能。当光从波导大端传输至小端, 渐变型和均匀型波导具有相似的弯曲附加损耗, 并且渐变型波导具有更高的耦合效率, 便于与多种光源耦合；当光从波导小端传输至大端, 渐变型波导的传输损耗和输出光束发散角更小。仿真了波导弯曲率、光源发散角和波导锥度等参数对传输损耗的影响。采用波长532 nm的半导体激光器作为光源, 进行了验证实验。测量数据与仿真结果有很好的一致性。

Characteristics of Gradually-Tapered Hollow Waveguide(GTHW) are investigated for terahertz wave transmission. Based on the ray-optics method, simulation analysis is made in detail on beam profile and transmission attenuation. Compared with Constant Diameter Hollow Waveguide(CDHW), GTHW has unique properties when light travels from large end to small end or in the opposite direction. When light travels from large end to small end, GTHW and CDHW have similar additional losses caused by bending, and GTHW has much higher coupling efficiency and is convenient coupled with various light sources. When light travels from small end to large end, GTHW has lower transmission loss and an output beam with smaller divergence angle. Influences of waveguide parameters on transmission attenuation are simulated, such as bending radius, light source divergence angle, and the angle of the taper slope. Verification experiments are carried by using laser diode radiating at the wavelength of 532 nm. Measured data show good agreement with the simulation results.