Reflection Volume Holographic Bi-directional Wavelength-Division Multi/Demultiplexers for Optical Communication

• Main Authors: I-Kai Pan, 潘奕凱
• Other Authors: Der-Chin Su
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/08627289598145001315

碩士 === 國立交通大學 === 光電工程所 === 89 === From the coupled-wave theory, it is obvious that the diffraction efficiency of a reflection-type volume hologram depends on the thickness, the average refraction index, the modulation refraction index of the recording material, and the reconstructed wavelength. Under optimal conditions, a reflection volume holographic element with maximum diffraction efficiency for a chosen wavelength, and minimum diffraction efficiency for another chosen wavelength is designed. Consequently, it can be used as a bi-directional wavelength-division multiplexer/demultiplexer (BIDI WDM) for optical communications. In order to demonstrate its feasibility, silver halide emulsions with a 5.7 m thickness and a diode-pumped solid-state laser with a 532nm wavelength are used. For experimental conveniences, 532nm and 632.8nm are chosen as two reconstructed wavelengths. Firstly, the average refraction index and the modulation refraction index of the silver halide emulsions with various exposures are measured with these reconstructed wavelengths. And their relation curves are depicted. Based on these results, the optimal exposures and its corresponding average refraction index and modulation refraction index can be obtained. Since this element is designed for BIDI WDM, any of the incident angle, the reflected angle and the diffracted angle equals 45o. Substituting these conditions into K-vector diagram, the recording geometry can be derived. Finally, an element is fabricated with the derived recording geometry and the optimal exposure. Its performance is estimated that it has transmission rates 3.979 dB and 1.549 dB for wavelengths 532nm and 632.8nm, respectively. And the elements for 1.3/1.55 m can be fabricated similarly.