Re: p- and s-polarization question

On Fri, 6 Nov 2003, zigoteau wrote:

> Timo Nieminen <[EMAIL PROTECTED]> wrote:
> > 
> > An alternative is to call them TE and TM, transverse electric and 
> > transverse magnetic modes, meaning basically the same thing as p and s. 
> > Also E and H polarisation are sometimes used.
> 
> TE=s and TM=p

TE mode has E transverse to the surface, ie parallel, so TE = p.

> > But that's just an aside. The real point is that you have an anisotropic 
> > film, in which case light polarised so that the electric field is normal 
> > to the dipoles (ie normal to the optic axis) is the [ordinary wave] and 
> > light with electric field parallel to the dipoles is the [extraordinary 
> > wave]. Two different sets of terminology, one for whether the electric 
> > field is parallel to the surface of the film, and the other for whether it 
> > is parallel to the dipoles.
> 
> This is not quite my understanding of the subject.
> 
> IMO the two categories are only appropriate in systems consisting of a
> stack of parallel slabs, the material of each of which is individually
> isotropic, or uniaxial with the axis normal to the slab interfaces.
> Because of the structure in the z-direction, the stack as a whole is
> anisotropic, but it is still symmetrical wrt rotation around the
> common interface normal. The eigenmodes of such a system then divide
> naturally into TE and TM (or s and p).

> For the TE modes, the E-field
> is perpendicular and the H-field parallel to the plane of incidence
> within any of the slabs, and vice-versa for the TM modes.

other way around

> Since TE and TM are eigenmodes, if you shine TE light in, the rays
> out, both reflected and transmitted, are also TE, and likewise for TM.
> However  this is not true for general anisotropic media.

Quite so. Basically, with other more general geometry, one ends up with 
the situation that the TE and TM fields are no longer eigenmodes, and 
become just descriptive labels for direction of polarisation.

-- 
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html