Influence of chromatic dispersion on a dual-wavelength passive-homodyne detection method for fiber-coupled interferometers.

The passive-homodyne method is very attractive for demodulating optical signals available at the output of interferometric sensors by the use of coherence multiplexing. Phase measurement and the use of two broadband sources with different central wavelengths permit a resolution of λ/10(5) to be achieved with a 20-µ range-sensor optical path difference. However, dispersive birefringent elements are required in this technique, which has some disturbing effects on the correlation signal position, on its envelope form, and on the measured phase. An analytical treatment of the problem and a numerical validation are described. Experimental evidence of the effects predicted by theory is presented.