[caption id="attachment_3088" align="alignleft" width="300"] Optical-complex-spectrum-anlyser-principle[/caption]

This paper explains clearly the patented method used by the Apex Technologies Optical Complex Spectrum Analyzer AP2441B/AP2443B developed in collaboration with France Telecom scientists. It is based upon a spectral analysis of the optical field; it extracts the amplitude and the phase of each frequency component (whereas classic optical spectrum analysers measure only the power spectral density, giving only the amplitude). By knowing the amplitude and the phase of each spectral component, the temporal variations of the amplitude and the phase can be calculated by means of the Fourier transform, providing the intensity, the chirp and the optical phase as a function of time.