A novel optical multilayer filter characterized by symmetrically stepwise graded refractive index profiles and high optical performance was designed. This 33-layer TiO2–SiO2 filter was fabricated by helicon plasma sputtering. The prepared filter exhibited a sharp cutoff reflection band around the central wavelength of 1340 nm and wide pass regions with high transmittance. These results correspond well with calculated estimations. Symmetrically stepwise graded refractive index profiles were demonstrated to effectively contribute to suppression of the sidelobes and to be potentially applicable in the design of other filters.
设计出了一种新型光学多层滤光片,其特点是具有对称的阶梯分级折射率轮廓和高光学性能。这种 33 层 TiO2-SiO2 滤光片是通过螺旋等离子溅射法制造的。所制备的滤光片在中心波长 1340 nm 附近有一个尖锐的截止反射带,并具有高透过率的宽通区。这些结果与计算结果十分吻合。实验证明,对称阶梯式分级折射率轮廓能有效抑制侧向波,并有可能用于其他滤波器的设计。