H. Kasai, M. Abe and S. Komatsu: Cascaded Fiber Bragg Grating as Optical Key for Personal Identification, Extended Abstracts (Optics and Photonics Japan 2007) (2007) 568-569.

We proposed to use a cascaded fiber Bragg grating (FBG) as a token-type optical key, the reflection or transmission spectrum of which plays the role of key pattern. Assigning different parameters to each element FBG in the cascade is expected to yield the variety of the key patterns. By examining the discrimination threshold between different key patterns, we show several methods to improve the discrimination properties.