利用特征矩阵法，研究了光波正入射时，厚度的阶梯性变化对远红外高反射光子晶体带隙的影响。结果表明，随着高折射介质层厚度的阶梯性增加，光子晶体高反射带的起始波长和截止波长都逐渐向长波方向移动，高反射带宽度也逐渐增大。高反射带起始波长、截止波长和高折射介质层厚度变化之间的关系可以分别利用一次方拟合表示，而高反射带宽度则需要利用二次方拟合才能达到理想的结果。

The relationship between the photonic band gap of highly reflective photonic crystals for far infrared and the ladder changes of thickness are investigated by means of the Characteristic Matrix Method. The results show that both the starting wavelength and cutoff wavelength gradually shift to the longer wavelengths when the dielectric layer thickness of high refractive index increases ladder. The widths of highly reflective band also increase. The interrelation of the starting wavelength, cutoff wavelength and the dielectric layer thickness of high refractive index changes can be respectively represented with one-square fitting, while the width of the highly reflective band need the quadratic fitting to achieve the desired results.