Experimental Study On Wavelengh Division Multiplexing Devices Based On Volume Holographic Grating

As a representation of high speed and great capacity transmission system, Wavelength Division Multiplexing (WDM) technology develops very fast in today's information era, and has had applications in world range. The technology of Dense Wavelength Division Multiplexing (DWDM) is becoming an available method for resolving the demand of bandwidth. So, developing the key device of Wavelength Division Multiplexing System is also becoming very important.Firstly, it is described amply that Transmission-Writing and Orthogonal-Readout (TWOR) scheme can be proposed for making wavelength filter in holographic media based on reviewing research status of WDM in domestic and abroad completely. In this paper, experiments on wavelength selectivity of volume holographic gratings with TWOR scheme are successfully conducted for the first time to our knowledge.Readingout by wavelength-tuning shows that a 3-dB bandwidth of 0.48 nm is achieved. This result approaches the standard of channel spacing for DWDM filters. In order to research the relationship between the diffraction properties, especially grating size ratio and wavelength selectivity of volume holographic gratings, different gratings with finite size are researched by experiments. The analysis of the experimental results shows that the 3dB bandwidth of volume holograph grating recorded with the TWOR scheme decreases when the ratio of volume holograph grating increases. It means that the wavelength selectivity of volume holograph gratings becomes better as the ratio of volume holograph gratings is less. When the ratio of volume holograph grating is more than 0.6, the 3dB bandwidth will be less than 0.5nm.The wavelength selectivity of volume holographic gratings is investigated by theoretical calculation based on two-dimensional (2-D) coupled-wave theory. The experimental measurement agrees well with the prediction of the 2-D coupled-wave theory.In this experimental and theoretical research, we have made progress in realization of TWOR scheme and how the ratio of volume holograph grating affects the resolution of grating. At last, we have a prospect about the future work and point out that the important works should be paid attention to in the future include improving the diffraction efficiency, improving wavelength resolution and researching more channels volume holograph grating.