Pilot Tones for Optical Signal Wavelength Identification and Power Measurement

摘要

A method of optical communication includes providing a plurality of optical signals each associated with a distinct channel of a composite optical signal. A unique pilot tone signature is superimposed on each channel. The spectral composition of each signature includes a plurality of frequencies. In one embodiment, binary frequency shift keying at a frequency fm is used to shift between instantaneous frequencies f1 and f2 wherein f2+Deltaf=f1-Deltaf=fc. Choosing $\frac{\mathrm{Delta}f}{f_m}\approx 1.1602$ produces a spectrum having a plurality of dominant components at least some of which have substantially the same amplitude. A method of detecting the presence of a selected pilot tone signature having a plurality n of dominant spectral components F1 . . . Fn includes generating a power spectrum P0(f). Sk(f) is calculated as a product of a plurality of frequency shifted versions of P0(f), where kepsilon{1 . . . n}. The existence of a dominant spectral component at Fk indicates the presence of the selected pilot tone signature.