An optical frequency-division multiplexing (OFDM) based self-healing unidirectional ring network is designed and its performance is verified. It employs arrayed waveguide grating add/drop multiplexers (ADMs) and erbium-doped fiber amplifiers (EDFAs) with waveguide level equalizers in each remote node. The route diversity configuration is employed to make the network robust and bit loss-free route switching is performed. The level diagram reproducibility for each OFDM channel is guaranteed by the waveguide-level equalizers. Successful transmission performance confirms the effectiveness of the proposed system.

The performance of a 5-GHz-spaced, 16-channel frequency selection switch (FS-SW) for optical frequency division multiplexing (FDM) distribution systems is described. The silica waveguide-type FS-SW is constructed with four serially connected periodic filters integrated on a silicon chip. The required crosstalk level for each periodic filter of the FS-SW was estimated to be -21.0 dB for a 16-channel FS-SW and 23.6 dB for a 128-channel FS-SW. Crosstalk can be independent of the power coupling ratio of the 3-dB-coupler regions by choosing suitable connecting configurations for the periodic filters. A controller for the switch is also described and the desired channel can be selected successfully from among 16 optical carriers under an average crosstalk level of less than -20 dB.>

A Mach-Zehnder (MZ) interferometer design is presented for application to wavelength-division multiplexed/frequency division multiplexed (WDM/FDM) systems. A variety of integrated-optic devices with low loss and low crosstalk, using silica-based waveguides, are demonstrated. MZ interferometers operate as multi/demultiplexers or frequency-selection switches. The channel spacing is determined by the waveguide arm length difference, and a spacing range of 1 GHz to 36 THz, corresponding to a wavelength spacing of 0.008-250 nm, is achieved. The devices for the WDM region have low fiber-to-fiber loss of 0.5 dB, and the devices for the FDM region have higher losses of 2-5 dB. Crosstalk of less than -15 dB was obtained for all the devices. A 5-GHz-spaced 16-channel frequency selection switch and a 10-GHz-spaced eight-channel multi/demultiplexer were also fabricated with a total loss of 5 dB and total crosstalk of -10 dB or less.>

Major factors affecting optical frequency division multiplexing (FDM) distribution system design are described. In particular, multiplexing/distribution configuration and channel-selection methods are compared from the viewpoint of the number of channels, the number of subscribers, and the transmission distance. The applicability of optical fiber amplifiers to the optical FDM information-distribution network is also discussed. The experimental results of a 5 GHz spaced 16-channel FDM distribution/transmission at 622 Mb/s, using a waveguide frequency-selection switch (tunable filter) and a multicarrier frequency-stabilization technique, are also discussed.>

Optical frequency-division-multiplexing distribution systems providing more than ten frequency multiplexed optical signals separated by on the order of gigahertz, distribute signals to plural receivers, where one of the signals is selected by a frequency selection switch (FS-SW). This paper describes the design of an optical frequency-divisionmultiplexing distribution system. Investigation is made of periodic filters for frequency division multiplexers and FS-SW, and the optical source, as well as single-mode fiber polarization mode dispersion. Preliminary transmission experiments using a bit rate of 450 Mbits/s, fiber length of 13 km, and frequency spacing of 11 GHz are also demonstrated at a 1.5 μm wavelength to show the design's suitability.