부산대학교 도서관

This article presents a simple polarization measuring device (PMD) developed indigenously for the simultaneous measurement of Stokes polarization parameters. Most of the standard Stokes parameters measuring techniques, particularly the one which uses wave retarder and linear polarizer, require at least half a rotation of either of polarization elements. Therefore, they cannot provide simultaneous measurement of Stokes parameters. Consequently, the time resolution of measurement is limited by the rotation period of polarization optics and the functionality of measuring setup is limited to beams with constant polarization state. In this work, a new device has been presented, which is capable of providing simultaneous measurement of beam intensities for both the constant as well as the time-varying state of polarization (SOP). It enables the estimation of first three Stokes parameters through four intensity measurements $\boldsymbol {I}(\boldsymbol {0} ^{\circ })$ , $\boldsymbol {I}(\boldsymbol {90}^{\circ })$ , $\boldsymbol {I}(\boldsymbol {45}^{\circ })$ , and $\boldsymbol {I}(\boldsymbol {-45}^{\circ })$ . The functionality of PMD has been verified on a test bench by using various known polarization states and comparing the results with measurements made using a rotating analyzer (RA). For each case, the parameters of polarization ellipse are deduced from the measured Stokes parameters. In addition to that, the corresponding polarization ellipses are constructed from the retrieved ellipse parameters. The ellipse parameters measured by PMD are compared with that measured using RA and the ellipses drawn from the PMD measurements are overlapped with that obtained using RA. The measurements made by RA are the reference measurements for finding the efficiency of PMD. The measurement accuracy of PMD is found to be $\le 0.01$ for values of axes $a$ and $b$ and it is $\le 0.5$ ° for the orientation angle $\psi $ of polarization ellipse. As the accuracy of measurement is comparable to other polarization measuring instruments/setups, any optical arrangement for which measurement is polarization-sensitive can use PMD for finding SOP. The main advantage of the PMD is that it can measure all requisite parameters of polarization ellipse, which is the most useful presentation of any polarization state and is capable of dealing with both the constant and time-varying SOP.