Experimental demonstration of the spectral interference between two beams of a low-coherence source at the output of a Michelson interferometer

The mutual interference of two beams of a low-coherence source has been demonstrated experimentally in the frequency domain at the output of a Michelson interferometer when the optical path difference (OPD) between both beams exceeds the coherence length of the source. The spectral interference between both beams, which shows up a periodic modulation of the source spectrum with the period dependent on the OPD, serves as an illustration of a technique for measuring both OPDs and displacements in a range dependent on the source spectrum width. Using a high-resolution spectrometer, good agreement between theoretical description of two-beam spectral interference experiment and the measured spectral modulation has been confirmed and the effect of both the spatial and the spectral integration has been resolved.