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An eight-channel dense wavelength division multiplexing (DWDM) system has been constructed and tested for applications to video, audio, and data transmission. The system uses DFB laser sources with wavelengths separated by 200 GHz and centered around the 1550 nm silica fiber transmission window. After transmission through the fiber, the demultiplexing of the signal requires that the optical wavelengths be separated while maintaining high isolation between channels, preferably with low insertion loss. Eight- channel DWDM demulitplexers are currently available with better than 20 dB isolation using one of several different approaches: planar arrayed waveguide gratings, bulk optical gratings, and multiple dielectric filters. For this system we are using a planar arrayed waveguide grating DWDM demultiplexer based on integrated optics fabrication techniques. The optical insertion loss ranged from 5 to 7 dB. Individual laser wavelengths were tuned to each respective demultiplexer channel by temperature tuning of the DFB laser. The overall system design requires that each wavelength carry 10 uncompressed video channel sat 8-bit coding, or 8 video channels of 10-bit coding. The data transmission rate is currently 1.2 Gbit/s per wavelength for an effective bandwidth of 9.6 Gbit/s. Results from our testing have shown channel separation of 1.6 nm with an isolation exceeding 30 dB. Bit error rates are less than 10-12 per wavelength channel. With 8-bit video, a total of 80 channels can be transmitted simultaneously with this approach. We conclude that a system of this design is well suited for the simultaneous transmission of multi- channel video, audio, and data, and will be a very appropriate system for multi-media applications. The system is also scaleable to even higher bit rates per wavelength and to a larger number of wavelengths. Thus, systems carrying more than 1000 uncompressed video channels simultaneously appear feasible.
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