Origin of interferogram asymmetry in optical-feedback semiconductor laser Michelson interferometer
We analyze the output wavelength dynamics of the semiconductor laser (SL) in an optical feedback (OF) Michelson interferometer (OSMI) and explain the origin of the observed asymmetry of the OSMI interferogram that is also sensitive to the displacement direction of the sample mirror relative to the SL facet. The Kobayashi-Lang mode solutions indicate an SL wavelength that varies only slightly about its nominal value and insufficient to cause the asymmetry. The power spectrum of the interferogram displays the perturbed nominal SL peak as well as the standing-wave solutions for the external resonators formed by the two interferometric arms. The standing-wave solutions do not affect the SL output wavelength because they are not matched with the profile of the SL gain medium. Their presence however, causes the interferogram to become asymmetric.