1. PC20312 Wave Optics Section 2: Polarization

2. Polarization states Image from Wikipedia linearcircularelliptical

3. Linear and circular polarization http://physics-animations.com/Physics/AVI/ellf.avi

4. Dipole radiation http://physics.usask.ca/~hirose/ep225/radiation.htm http://www-antenna.ee.titech.ac.jp /~hira/hobby/edu/em/dipole2/dipole2.html E Optical E-field……drives oscillating dipoles in the medium… …which radiate in all directions except parallel to E. www.harvard.edu/~efortin/thesis/html/EMR_light.shtml

5. Polarization by reflection Click here for a web-based animation of Brewster’s angle E perpendicular to plane of incidence “s-polarised” Emission always max in direction of E r E parallel to plane of incidence “p-polarised” Emission amplitude varies with direction of E r EiEi ErEr EtEt EiEi ErEr EtEt

6. Brewster’s angle,  B Sir David Brewster 1781-1868 EiEi E r =0 EtEt tt BB ntnt nini P-polarised light

7. Polarization by scattering E in vertical  no vertical scattering E in horiz.  no horiz. scattering Animation from http://www-antenna.ee.titech.ac.jp/~hira/hobby/edu/em/smalldipole/force.gif For unpolarised incident light the scattered light is: Completely polarised in vertical  horiz directions Partially polarised in intermediate directions unpolarised polarised partially polarised

8. Polarized light in nature Image from Wikipedia Unfiltered imageImage seen through polarising filter

9. Polaroid PVA structure from http://wwwchem.csustan.edu/CHEM2000/EXP2/bkg.htm  Polaroid sheet eg aligned PVA molecules E cos  E sin  E cos  E-field component aligned with long axis of molecule is absorbed E

10. Malus’ Law Etienne-Louis Malus 1775-1812 http://physics-animations.com/Physics/AVI/polariz.avi

11. Anisotropic Materials Image from Wikipedia Calcite CaCO 3 EyEy ExEx PyPy PxPx n o = 1.658 & n e =1.486 (at =590 nm) For calcite:

12. Birefringence E o perpendicular to k & optic axis E e perpendicular to E o z y x k   EoEo EeEe Optic Axis EoEo

13. Double Refraction Image from Wikipedia unpolarised light Optic Axis e-ray o-ray For calcite, typical angle between beams ~6 

14. Polarizing Beamsplitter polarised light unpolarised light Optic Axis points towards you polarised light calcite transparent glue o-ray e-ray Photo from http://www.lightmachinery.com

15. Waveplates Optic Axis d z y x n o >n e : Optic Axis is ‘fast’ n e >n o : Optic Axis is ‘slow’ Photo from http://www.lightmachinery.com In this diagram, is the optic axis slow or fast?

16. The Faraday Effect Image from http://en.wikipedia.org/wiki/Faraday_effect Material V (rad.T -1.m -1 ) Glass 9.2  10 -4 Water 3.8  10 -4 Air 1.8  10 -7 Quartz 4.8  10 -4 Terbium Gallium Garnet -40

17. Faraday Isolator 45  P1P1 P2P2 E B P1P1 P2P2 B E