中国物理B ›› 2012, Vol. 21 ›› Issue (5): 54219-054219.doi: 10.1088/1674-1056/21/5/054219
张俊超1 2,方明1,邵宇川1 2,晋云霞1,贺洪波1
Zhang Jun-Chao(张俊超)a)b), Fang Ming(方明)a), Shao Yu-Chuan(邵宇川)a)b), Jin Yun-Xia(晋云霞)a), and He Hong-Bo(贺洪波)a)†
摘要: The design and the deposition of a rugate filter for broadband applications are discussed. The bandwidth is extended by increasing the rugate period continuously with depth. The width and the smoothness of the reflection band with the distribution of the periods are investigated. The improvement of the steepness of the stopband edges and the suppression of the side lobes in the transmission zone are realized by adding two apodized rugate structures with fixed periods at the external broadband rugate filter interfaces. The rapidly alternating deposition technology is used to fabricate a rugate filter sample. The measured transmission spectrum with a reflection bandwidth of approximately 505 nm is close to that of the designed broadband rugate filter except a transmittance peak in the stopband. Based on the analysis of the cross-sectional scanning electron microscopic image of the sample, it is found that the transmission peak is most likely to be caused by the instability of the deposition rate.
中图分类号: (Filters, zone plates, and polarizers)