How can I measure the TE TM splitting in Microcavities?

[Martin91]

HI all,

I think I have to use some combination of waveplates on the signal, but I am not sure, does anybody know this?

Thanks for help

 

[Cthugha]

Are you looking at a planar microcavity or is it a structured one, e.g. a micropillar?

Generally speaking, the TE and TM modes are the linear polarizations with either the electric or the magnetic field oriented perpendicular to the plane given by the normal vector of the microcavity plane and the wave vector of the light field. Therefore, the TE-TM splitting will obviously be slightly different for each value of k along the dispersion and it is 0 for normal incidence.

So you need polarized light and a half wave plate to rotate the polarization of the light field. One possible way to do this is to perform angle-resolved reflection or transmission measurements using polarized white light. If you do not know, at which angle you need to put the half wave plates, just rotate them until you find the lowest and highest energies for some given angle. These should appear at orthogonal angles. The splitting is, however, usually not large. Depending on the material, it may be a feww 100 microeV, though.

 

[Martin91]

thanks a lot for your answer, basically I just put a lambda half plate in my excitation path and find the highest/lowest energy dispersion on higher k vectors yes? and nothing in my signal path ?

in my case it is a 1 dimensional ridge GaAs

 

[Cthugha]

thanks a lot for your answer, basically I just put a lambda half plate in my excitation path and find the highest/lowest energy dispersion on higher k vectors yes? and nothing in my signal path ?

Well, if you already have polarized light, you just put a lambda half plate. Otherwise, you need to place a Glan or some other polarizer in your beam path first of course. What kind of light source will you use? Will you measure in transmission or reflection?

For details on one example system, see G. Panzarini et al., Phys. Rev. B 59, 5082 (1999) and ref. 21 therein.

 

[Martin91]

thanks for your help so far, is in reflection and a continuous laser, I put a linear polarizer and after it a lambda half plate rotated it, but the dispersion relation did not change, I am not sure if I also have to put something in the detection path?

 

[Cthugha]

This may be difficult. What is the spectral resolution of your detector? What is the resolution with which you can scan the angle of incidence of the light beam? What is the angular width of the beam? The shift you try to see might be very small and it will be 0 at normal incidence.