Phase Induced Intensity Noise in Concatenated FiberOptic Delay Lines

A fiberoptic differential delay line structure, often used in modern architectures of fiber sensors, sensor arrays, fiberoptic signal processors, and local area networks, 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 tie two systems. The power spectrum of the noise at the output of concatenated systems; whose building blocks are the Mach-Zehnder and the reirculating delay lines, is theoretically studied with special emphasis on polarization effects. An experimental verification is also presented for the interesting case of two recirculating delay lines in series.