Interferometric characterization of the structured polarized light beam produced by the conical refraction phenomenon

A. PEINADO; A. TURPÍN; C. IEMMI; A. MÁRQUEZ; T. KALKANDJIEV; J. MOMPART; G.J. TURIACCI

OPTICS EXPRESS

OPTICAL SOC AMER

Lugar: Washington; Año: 2015 vol. 23

1094-4087

The interest on the conical refraction (CR) phenomenon inbiaxial crystals has revived in the last years due to its prospective forgenerating structured polarized light beams, i.e. vector beams. While theintensity and the polarization structure of the CR beams are well known, anaccurate experimental study of their phase structure has not been yet carriedout. We investigate the phase structure of the CR rings by means of a Mach-Zehnder interferometer while applying the phase-shifting interferometrictechnique to measure the phase at the focal plane. In general the two beamsinterfering correspond to different states of polarization (SOP) whichlocally vary. To distinguish if there is an additional phase added to thegeometrical one we have derived the appropriate theoretical expressionsusing the Jones matrix formalism. We demonstrate that the phase of the CRrings is equivalent to that one introduced by an azimuthally segmentedpolarizer with CR-like polarization distribution. Additionally, we obtaindirect evidence that the Poggendorff dark ring is an annular singularity,with a π phase change between the inner and outer bright rings.