Priyanka Lochab

Indian Institute of Technology Delhi | IIT Delhi · Department of Physics

We study the propagation of a charge-1 vortex beam using the angular spectrum method. While vortex beams are commonly assumed to have a helical wavefront, it is well known that the phase of the vortex in the near-core region varies arbitrarily quickly. In order to explain the wavefront behavior in the near-core region, ideas such as evanescent fiel...

Abstract: We describe a laser beam engineered to carry l = 0 and l = 1 orbital angular momentum (OAM) states in orthogonal polarizations. It is observed that on collinear transmission through a random phase screen, the far field diffraction intensity patterns for the individual polarization states are complementary with significant negative correla...

We report experiments on propagation of scalar and vector optical beams through random phase screens mimicking turbulence and show that the intensity profile of the beam containing a C-point polarization singularity shows maximally robust behavior. This observation is explained in terms of the polarization and orbital angular momentum (OAM) diversi...

We report investigations on propagation of converging vector beams containing C-point and V-point polarization singularities through atmospheric turbulence. The C-point singularity is generated by superposition of the 𝑙=0 and 𝑙=1 orbital angular momentum (OAM) states, whereas the V-point singularity is generated by a superposition of the 𝑙=−1 and 𝑙...

We show that the far-field speckle patterns observed on the transmission of polarization structured light beams through a random diffuser screen have distinct spatial textures, which significantly differ from the texture of the fully developed scalar speckle. In particular, we report on speckle observed using the V-point and C-point polarization si...

Orbital Angular Momentum States of Light provides an in-depth introduction to modelling of long-range propagation of orbital angular momentum (OAM) modes as well as more general structured light beams through atmospheric turbulence. Starting with angular spectrum method for diffraction and description of structured light states, the book discusses...

We report experiments on propagation of scalar and vector optical beams through random phase screens mimicking turbulence and show that the intensity profile of the beam containing a C-point polarization singularity shows maximally robust behavior. This observation is explained in terms of the polarization and orbital angular momentum (OAM) diversi...

Beams carrying C-point polarization singularity (lemon and star) are experimentally shown to maintain robust intensity profile on passing through a random medium compared to beams carrying V-points polarization singularity (radially and azimuthally polarized).

The iterative phase retrieval algorithms such as the Gerchberg-Saxton (GS) method and the Fienup Hybrid Input Output (HIO) method are known to suffer from the twin image stagnation problem, particularly when the solution to be recovered is complex valued and has centrosymmetric support. Recently we showed that the twin image stagnation problem can...