Abstract: The is directed to extending wavelength routing on a metro network subtended off an optical agile network. Flexibility on the subtended metro network is obtained by either tuning the head-end transmitter on a metro wavelength that is the operating wavelength of the route to a specified tail-end node (tunable source, fixed wavelength-route dependency) or/and tuning a specified route to the metro wavelength (fixed source, tunable wavelength-route dependency). The routes may be tuned at one or both ends.

Abstract: A line amplification system connected on the fiber between two flexibility sites of a wavelength switched network is built with a number of modules that can be arranged in a line amplifier, preamplifier and postamplifier configurations. The line and preamplifiers include a Raman module and a two-stage EDFA module provided with mid-stage access. A dynamic gain equalizer is connected in the mid-stage in the line amplification configurations. As well, dispersion compensating module may be connected in the mid-stage whenever/if needed. A line monitoring and control system operates the line amplification system so that all channels traveling along a link have substantially the same power, in the context of channels being added and removed to/from the line arbitrarily.

Abstract: A Raman module comprises a detecting unit for measuring the output power of a WDM signal traveling along a fiber section, and a spectral gain estimating unit for determining an estimated vector gain Gainmeas based on the output power alone. The Raman pump signal is controlled with a gain GainRA evaluated based on the estimated gain Gainmeas so that all channels have a similar gain. The spectral gain estimating unit comprises a fiber gain model and an input signal adjust unit. The model receives the output power, assumes a predicted input power for each channel and provides a corresponding estimated output power for each channel. The input signal adjust unit adjusts the predicted input power based on an error signal provided by the model. The gain is then calculated from the predicted input powers and the estimated output powers. The detecting unit demultiplexes a fraction of the WDM signal into n sub-band and detects sub-band optical power PB1, . . . PBn.

Abstract: A return-to-zero (RZ) modulator for an optical transmitter comprises a Mach-Zehnder interferometer optically coupled with a light source for modulating a continuous wave generated the said light source with a drive signal. A drive circuit generates a drive signal for modulating the Mach-Zehnder device to generate an optical RZ pulse signal with adjustable width. The drive circuit comprises a trigger flip-flop for converting a non-return to zero (NRZ) signal to a modified drive signal. A method of generating an optical RZ pulse signal comprises converting a non-return to zero (NRZ) signal to a modified drive signal, and modulating a continuous wave from a light source with the modified drive signal to generate an optical RZ pulse signal. The width of the pulses in the optical RZ pulse signal is controlled by adjusting the rise and fall time of the modified drive signal.