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光纤色散会使脉冲展宽,从而导致误码,在通信网中这是必须避免的一个问题。运用有限元法,在考虑石英基质材料色散的前提下,数值模拟了呈圆形排列的双包层光子晶体光纤的场分布、基模有效折射率和色散特性。结果表明,小空气孔间距和直径不变时,大空气孔与第一圈小孔的的间距和大空气孔的直径对色散曲线的走向起决定性作用。如同某些色散补偿光纤一样,有效模折射率会在某个波长处过渡,从而实现平坦色散,如当直径d1=3.1μm,d2=1μm,间距Λ1=5μm,Λ2=4μm时,在1.22～1.6μm超宽波长范围内,其色散值Dmax-Dmin<4ps/(nm·km)。
Fiber dispersion will pulse broadening, resulting in error code, which is a problem that must be avoided in the communications network. With the finite element method, the field distribution, the effective refractive index and the dispersion of the fundamental mode of a double-clad photonic crystal fiber are numerically simulated considering the dispersion of quartz matrix material. The results show that when the spacing and diameter of small air holes are constant, the distance between the large air hole and the first lap and the diameter of the large air hole play a decisive role in the dispersion curve. As with some dispersion-compensating fibers, the effective modal index will transition at a wavelength to achieve flat dispersion such as d1 = 3.1μm, d2 = 1μm, spacing Λ1 = 5μm and Λ2 = 4μm, 1.6μm wide wavelength range, the dispersion value Dmax-Dmin <4ps / (nm · km).