Complex Spectrum Analysis of Modulated Optical Signals Using Stimulated Brillouin Scattering

We introduce a novel method for the measurement of the spectral phase of modulated optical signals based on double-pump stimulated Brillouin scattering interaction and direct homodyne detection. This technique is combined with Brillouin high-resolution analysis to achieve a complete characterization of the complex optical spectrum. A 10-Gb/s nonreturn-to-zero signal with a 32-bit pattern modulated with an electroabsorption modulator is measured using this technique and its time-domain information (power and chirp) is obtained by inverse Fourier transform.