Abstract
We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.
Highlights
Singular optics is the new branch of modern physical optics that deals with a wide class of effects associated with phase singularities in wave fields and topology of wave fronts [1]
In this paper we present our experimental results on the wavelength dependence of the vector inhomogeneity and of the polarization singularity generated in the output of a two-mode optical fiber (TMF)
For the input wavelength of the Ti: Sapphire laser tuned to λ1 = 740 nm and the half-wave plate (HWP) oriented at 0◦, the linear vertically polarized Gaussian beam is coupled into the cleaved input end of the TMF
Summary
Singular optics is the new branch of modern physical optics that deals with a wide class of effects associated with phase singularities in wave fields and topology of wave fronts [1]. In this paper we present our experimental results on the wavelength dependence of the vector inhomogeneity and of the polarization singularity generated in the output of a two-mode optical fiber (TMF). Using the normalized Stokes parameters (S1/s0, S2/s0, and S3/s0) the trajectory at a point of the elliptically polarized output beam from the TMF is tracked on the Poincaresphere as a function of input wavelength. The output beam intensity and the polarization ellipse parameters (b, ψ) show periodic behaviour, clearly indicating change in the rotation direction of the polarization ellipse from right to left through linear polarization as a function of wavelength of the input beam, in the linear regime of operation. The wavelength scanning method for such measurements has the added advantage that the orientation of the fiber is not altered during the measurements and is a nondestructive method
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