N-port optical circulators with holographic spatial walk-off polarizers

• Main Authors: Jing-Heng Chen, 陳敬恒
• Other Authors: Prof. Der-Chin Su
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/37129505355820928713

博士 === 國立交通大學 === 光電工程所 === 92 === The effects on holographic optical elements (HOEs) due to the film shrinkage and the refractive index shift are studied. Based on the geometries of the K-vector diagram, a compensation method to physically correct these effects in the fabrication of hologram for HOEs is proposed. This method is applicable to single-exposed and multiply-exposed volume holograms. In order to show the validity, volume holograms with special specifications are fabricated with silver-halide recording materials. The experimental results show good correspondence with the theoretical values. The methodology proposed is applicable to other phase media when the associated film shrinkage and refractive-index shift data are experimentally determined. Based on the characteristics of holographic recording materials and the coupled-wave theory, a volume holographic spatial walk-off polarizer (HSWP) is proposed to replace the conventional birefringent crystal spatial walk-off polarizers. An alternative type of 4-port optical circulator using HSWPs is designed. Furthermore, a holographic spatial- and polarization- module (HSPM) is proposed and it can be used to setup several different types of multi-port optical quasi-circulators. The prototypes are fabricated and experimentally tested. Moreover, the operating principles, the characteristics and the performances of these devices are discussed. The merits of these designs include polarization-independence, compactness, high isolation, low polarization mode dispersion, and easy fabrication. In addition, the port number can be scaled up easily.