Phase induced intensity noise in concatenated fiber-optic delay lines

A fiber-optic differential-delay-line structure converts the phase noise of its short coherence source to intensity noise at its output. If this structure is followed by a similar system, intensity noise is generated as well as filtered by each of the two systems. The power spectrum of the noise at the output of concatenated systems built of Mach-Zehnder and the recirculating delay lines is theoretically studied. The spectral structure of phase-induced intensity noise at the output of these concatenated systems is analyzed, taking into account polarization effects and emphasizing the physical interpretations of the results. An experimental verification is presented for the case of two recirculating delay lines in series