Techniques for detecting densely wavelength-multiplexed solitons

Long distance data transmission using solitons multiplexed on different wavelengths makes more efficient use of fiber bandwidth than transmission on a single wavelength channel. However, perturbations and nonlinear distortions limit the number of wavelengths which can be multiplexed and detected at the end of the fiber. Perturbations, such as loss, cause permanent frequency shifts if a collision occurs between solitons widely separated in frequency. Densely packing the solitons spectrally, though, results in distortions in spectral intensity which limit the use of standard wavelength demultiplexing techniques. We examine methods by which solitons, densely multiplexed in wavelength, may still be detected even during collisions. The theoretical feasibility of encoding the data on the eigenvalues of the linear evolution equations associated with soliton propagation by the inverse scattering transform is discussed, as are more practical techniques using only the spectral intensity of the waveform.