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Design and characterization of a simple polarization grating-based polarimeter

Massimo Santarsiero, J. C. G. de Sande, Gemma Piquero

Abstract

In undergraduate optics courses, diffraction gratings are studied extensively, generally within the scalar approximation. When the vector nature of light is taken into account, so-called polarization diffraction gratings have been proposed, which are a cutting-edge research topic due to their numerous applications. This paper proposes a simple experiment to introduce students to polarization diffraction gratings and, at the same time, use this device to apply many of the concepts learned about polarimetry. Although current research uses spatial light modulators and metasurfaces, we use a cheap commercial polarization grating. In addition to show how a polarization grating can be characterized, its use as a cheap and easy-to-use Stokes polarimeter is described and demonstrated experimentally. In performing the experiment, issues typical of inverting linear systems will arise, and this will also provide the opportunity to address the problem of finding well-conditioned systems of equations.

Design and characterization of a simple polarization grating-based polarimeter

Abstract

In undergraduate optics courses, diffraction gratings are studied extensively, generally within the scalar approximation. When the vector nature of light is taken into account, so-called polarization diffraction gratings have been proposed, which are a cutting-edge research topic due to their numerous applications. This paper proposes a simple experiment to introduce students to polarization diffraction gratings and, at the same time, use this device to apply many of the concepts learned about polarimetry. Although current research uses spatial light modulators and metasurfaces, we use a cheap commercial polarization grating. In addition to show how a polarization grating can be characterized, its use as a cheap and easy-to-use Stokes polarimeter is described and demonstrated experimentally. In performing the experiment, issues typical of inverting linear systems will arise, and this will also provide the opportunity to address the problem of finding well-conditioned systems of equations.
Paper Structure (8 sections, 51 equations, 6 figures, 3 tables)

This paper contains 8 sections, 51 equations, 6 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Preliminaries
  3. Jones formalism and Stokes parameters
  4. Mueller formalism
  5. Polarization gratings
  6. Experimental characterization of a polarization grating
  7. Polarization grating as a Stokes polarimeter
  8. Conclusions

Figures (6)

  • Figure 1: The Poincaré sphere. Are explicitly shown: linearly polarized states along $x$, $y$ and along an angle at $\pm \pi/4$ with respect to $x$, right- and left-handed circularly polarized states.
  • Figure 2: Scheme of a simple polarization grating, a transparency in which the polarization of the incident wave is changed periodically along a line. Arrows indicate the transmission axis direction of a polarizer.
  • Figure 3: Experimental setup. $\rm{QWP_G}$: quarter-wave phase plate; $\rm{LP_G}$: removable linear polarizer; PG: polarization grating; $\rm{QWP_A}$: removable quarter-wave phase plate; $\rm{LP_A}$: linear polarizer; PM: power meter.
  • Figure 4: Measured polarization ellipse of the input light and those corresponding to different diffraction orders. The calculated polarization ellipses are also shown for comparison. Red (green) ellipses denote right-handed (left-handed) polarization.
  • Figure 5: Measured polarization (St) ellipse of the input light and calculated polarization (PG) ellipse from the measured powers for diffracted orders $n=\pm 1$, $n= \pm 3$ and $n=\pm 4$. Red (green) ellipses denote right-handed (left-handed) polarization.
  • ...and 1 more figures