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Optical Networks Optical Circuit Switching (OCS)

Optical Networks Optical Circuit Switching (OCS). Cheyns: Optical packet switched... AWG. Results from the EU IST-project STOLAS Optical packet/burst switches requires fast (ns) reconfigurable switching matrixes. AWG with fast tunable wavelength converters is an alternative. .

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Optical Networks Optical Circuit Switching (OCS)

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  1. Optical NetworksOptical Circuit Switching (OCS)

  2. Cheyns: Optical packet switched... AWG • Results from the EU IST-project STOLAS • Optical packet/burst switches requires fast (ns) reconfigurable switching matrixes. • AWG with fast tunable wavelength converters is an alternative.

  3. Arrayed waveguide Grating • 1 X N or N X N coupler spreads the light in N waveguides with different lengths • Waveguides are merged and create interference • Each wavelength will constructively recombine at only one given output port and cancel out on the others, due to the phase difference

  4. AWG switching principle • Cyclic • F fibres , W wavelengths • Same output for lj as for lj + WDl • Table: Given input port and wavelength, the output port is found from the table.

  5. Simple AWG node architecture • Internal blocking when two inputs with the same l to the same fibre • No conversion at output • Conversion range at input: l0 to l3 required • Limits which output port the input can be connected to => blocking • Internal blocking may be relaxed by smart choices of output wavelengths for converters and many wavelengths. l0

  6. No blocking version • Input converters must be able to convert to seven different wavelength converters: Larger wavelength range. • Fixed wavelength at output converters for multiplexing • Only one wavelength for each output. • Potential problems with scaling, size of AWG.

  7. Using smaller AWGs • Future networks have many wavelengths: Scalability • Simple to add an extra input: Add extra input on optical coupler (cheap). • AWG with W input/output ports • Two inputs which is combined can not be converted to the same l: Contention • Couplers at output ports • Same blocking properties as the first design. (Same l setting) • Scales with W rather than F*W (first design)

  8. Small AWG, many internal wavelengths • Nonblocking • F*W internal wavelengths • 2F multiplexers with size F*W • Several wavelengths on each output port. • W*F2 TWC’s with conversion grade W • Tunable converters at output

  9. Alternative solution (multiport): • Reduced size of muxes and number of converters • Still nonblocking • Still FW internal wavelengths • FW fixed output wavelength converters • W demultiplexers, but F smaller/cheaper Foretrukket!

  10. Optical Pan European Network (The OPEN project) • Broadcast & Select switching architecture, non-blocking • Multicast is simple • Scaling a problem, attenuation in couplers. All inputs available for all outputs

  11. Norway-Denmark field trial

  12. Field trial • OXC, wavelength conversion, Optical Add/drop • Mix of SDH and Pseudo Random Bit sequences (PRBS) • Different fibre types, Dispersion Compensating Fiber (DCF), amplifiers, transponders

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