19 May 2009 1×2 demultiplexer for a light waveguide communications system based on a holographic grating
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2-channel multiplexer/demultiplexer (Muxer/Demuxer) is a key component for bidirectional data traffics applied for optical communication. Up to date various types of Muxer/Demuxer have been proposed and demonstrated. A grating coupler diffracts light into substrates or waveguides, along which light beam propagates by total internal reflection. In addition, one can exploit the dispersive and filtering characteristics of gratings, for dropping or separating one or several wavelengths from one another. When a laser beam containing two wavelengths is striking the surface of the grating with an incident angle within certain range, four diffracted beams will be generated. If two diffracted beams, corresponding to different wavelengths, meet the condition of total internal reflection, they will propagate inside the glass substrate (performs as a waveguide). While the third one cannot meet total reflection condition, and the last one should become the evanescent wave. Therefore it can separate two signals and couple signals to different waveguides. These functions are suited for WDM application and directional couplers. For convenience sake, the visible lights at 458nm and 633nm were used as the incident laser beams. To give a simple sample for 1×2 demultiplexing system, a holographic grating was recorded, with the period around 441nm which was chose discretionally within the certain range. The primary experimental results indicate that the two-wavelength signal can be separated and coupled into the respective waveguide as long as the grating is recorded and operated complying with the certain condition. The average insertion loss and crosstalk of the device were presented in this paper.
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Xuechang Ren, Xuechang Ren, Xiangsu Zhang, Xiangsu Zhang, Canhui Wang, Canhui Wang, Shou Liu, Shou Liu, } "1×2 demultiplexer for a light waveguide communications system based on a holographic grating", Proc. SPIE 7358, Holography: Advances and Modern Trends, 73580L (19 May 2009); doi: 10.1117/12.819793; https://doi.org/10.1117/12.819793

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