新型THz波超平坦色散光子晶体光纤

A new type of THz photonic crystal fiber with super-flattened dispersion

设计出一种新型的渐变空气孔径THz波超平坦色散光子晶体光纤.应用时域有限差分方法(finite-difference time-domain,FDTD)计算光纤色散,所得结果表明渐变空气孔径光子晶体光纤比孔直径不变光子晶体光纤控制色散的能力更强;且当第三层与第四层空气孔直径相同时,孔直径渐变的光子晶体光纤的色散更趋于平坦,而当空气孔直径取d1=0.85d4,d2=0.95d4,d3=d4(d1,d2,d3,d4分别为包层从内到外空气孔的直径)时,此种光子晶体光纤可以在波长60—65μm(4.61—5THz)范围内将波导色散值控制在-0.1±0.3ps/(km·nm)范围内,得到趋于超平坦色散的、具有很好的束缚THz波的能力和良好的损耗特性的新型THz波光子晶体光纤.

A new type of THz photonic crystal fiber with super-flattened dispersion and air hole varying cladding is designed in this paper. Its dispersion properties are analyzed by using the finite-difference time-domain （FDTD） method. The results show that the new THz photonic crystal fiber is better than THz photonic crystal fiber with air hole unarying cladding in controlling the dispersion,and that the new THz photonic crystal fiber has the flattened dispersion when the third ring diameter has the same value as the forth ring diameter. When the air hole diameters are d1 = 0. 85d4,d2 = 0. 95d4,d3 = d4 （d1,d2,d3,d4 are the diameters of air hole from the inter clad to the outer clad）,the new THz photonic crystal fiber can have almost super-flattened dispersion at a level of - 0. 1 ± 0. 3 ps /（nm·km）,a good ability to restrict the THz wave and a low loss in a wavelength reange between 60 μm and 65 μm.