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 f_m is used to shift between instantaneous frequencies f₁ and f₂ wherein f₂+Δf=f₁−Δf=f_c. Choosing; $$ \frac{\Delta f}{f_m}\approx 1.1602$$ ;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 . . . F_n includes generating a power spectrum P₀(f). S_k(f) is calculated as a product of a plurality of frequency shifted versions of P₀(f), where kε{1 . . . n}. The existence of a dominant spectral component at F_k indicates the presence of the selected pilot tone signature.