用时域有限差分(Finite Difference Time Domain-FDTD)算法模拟了光从真空垂直入射到表面覆盖有一层纳米孔隙聚合物薄膜的玻璃介质,得到了在不同波长下的纳米孔隙薄膜的透过率谱线.将FDTD模拟结果的透过率谱线与理论谱线相对照,估算出了该薄膜的等效折射率.我们分别模拟了孔隙率为5%、10%、15%、20%和30%的薄膜,得到了它们的透过率谱线,而且利用这些谱线得到了它们不同的等效折射率值.文末给出了只有两层薄膜构成的纳米孔隙宽带增透薄膜的结构,而且利用FDTD算法模拟了光经过这种增透膜入射到玻璃介质的过程,结果显示这种增透膜在可见光波长范围的透过率高达99.5%.

The finite difference time domain (FDTD) method is used to simulate light propagating from vacuum to glass material covered with nano-porous films, and the transmittance spectrum with different wavelength are obtained. Compared with theoretical spectrum, the refractive index of the nano-porous film is calculated. A series of nano-porous films with the porous ratio of 5%、10%、15%、20% as well as 30% are simulated. In the end of this paper, a broad-band antireflection coating composed of the nano-porous film and one MgF2 layer is proposed. Simulated this antireflection coating by FDTD method, the average transmittance can be reached above 99.5% between 400nm and 800nm.