Polarization and scattering Clause Samples

Polarization and scattering. × In this last Section, we study the polarization of the light transmitted through a cavity, com- prising again a flat and a concave mirror, but now with a polarizer behind the resonator. We inject vertically polarized light off-axis at an angle, as compared to the optical axis, in the 8- fold frequency-degenerate cavity (L = 2 mm). For a transmission axis of the polarizer parallel to the input polarization we clearly observe 8 hit points on the mirror as shown in Fig. 7.4a. When we rotate the polarizer over 90◦, we still observe the hit points on the mirror as shown in Fig. 7.4b. This is surprising as intuitively one would expect that the polarization should be preserved inside the resonator, and the component perpendicular to the input polarization would be zero. In practice, the light behind the cavity contains, however, a surprisingly large component with a polarization perpendicular to the input polarization. More specifically, the intensity in the hit points is only 75 weaker for polarization perpendicular to the input po- larization than for the parallel component. This observation is not an artifact of our polarizer. Our PolarcorTM polarizer (Newport 05P109AR.16) is well-suited for this experiment: it has a specified acceptance angle as large as 15◦ (typical angles for our configuration are 2◦) and the combination of the laser and the polarizer has a measured extinction ratio of 35000 : 1 for normal incidence.