双芯太赫兹光纤定向耦合器

Dual-Core Terahertz Fiber Directional Coupler

提出了一种双芯太赫兹光纤定向耦合器,两介质圆柱分别悬挂于两环形介质层的内部,形成光纤的两个纤芯,通过调节结构参数可使两偏振模耦合长度相等,从而实现了耦合长度与偏振无关的特性。耦合器件长度可为光纤模式耦合长度的1/2,器件长度较短,这降低了模式传输损耗。采用有限元法对耦合器进行了数值分析研究,结果表明:耦合器的长度为0.535 cm,x和y偏振模的传输损耗分别为0.23 dB和0.19 dB;在保证两偏振模的耦合长度差小于1%的前提下,其带宽可达到220 GHz。

In this paper, a two-core terahertz fiber directional coupler is proposed. Two dielectric cylinders are suspended in the interior of two annular dielectric layers to form two fiber cores. By adjusting the structural parameters, the coupling length of the two polarization modes can be equal, thus realizing polarization independence of the coupling length. The length of the coupler can be one half of the coupling length of the fiber mode, and the transmission loss can be reduced with the short length of the device. The coupler is numerically analyzed by finite element method. The results show that the length of the coupler is 0.535 cm, and the transmission loss of x and y polarization modes is 0.23 dB and 0.19 dB, respectively. Under the premise that the coupling length difference between the two polarization modes is less than 1%, the bandwidth reaches 220 GHz.