Temporal Correlation Vortices and Topological Dispersion

Interference measurements of a polychromatic partially coherent light source verify the existence of a temporal correlation vortex. Topological dispersion is found to destabilize this singularity.

Figure 1

(a) Simplified schematic of Mirau interferometer and eight-level spiral glass plate. The lamp and filter are characterized by a center wavelength, ${\lambda }_0$, and a FWHM bandwidth, $\Delta \lambda$. A $51.8\times \mathrm{\text{microscope objective}}$, $L_1$, having a numerical aperture of 0.55 was used along with a camera lens, $L_2$, to image the surface of the plate near the camera detector array. The optical path length difference was scanned by translating the mirror relative to the beam splitter, $B{S}_2$. (b) Reconstructed surface profile of the plate with a measured pitch of $\Delta h=1.52\mu \mathrm{m}$. (c) Typical interference profile. (d) Interference profile obtained when the mirror is tilted, making the object and reference beams nonparallel.

Figure 2

Correlograms at ${\lambda }_0=583\mathrm{n}\mathrm{m}$ through the correlation vortex core for a $\Delta \lambda =20\mathrm{n}\mathrm{m}$ bandwidth light source showing a stable correlation vortex having negligible fringe visibility in both the (a) $x\mathrm{\text{−}}\tau$ ($y=0$) and (b) $y\mathrm{\text{−}}\tau$ ($x=0$) planes. The graphs depict the different fringe visibility inside (black) and outside (gray) the vortex core.

Figure 3

Correlograms of an unstable correlation vortex having a bandwidth of $\Delta \lambda =300\mathrm{n}\mathrm{m}$.