On this page, polarization incoherence and methods to simulate it are discussed.
- Circular polarization
- FDTD and coherence
- Incoherent dipole
- Unpolarized beam
- Incoherent unpolarized dipole
Problems with direct simulation
In a similar manner to temporal phase incoherence, the polarization of a beam or the orientation of a dipole source depends on time. In the case of an unpolarized beam we have
where the unit vector u(t) defines the beam polarization and varies on a time scale τc >> T.
In the case of a dipole source, we have
In both cases, the time scale for the variation of the polarization is much larger than the optical cycle, making it unpractical to simulate the statistics of temporal polarization incoherence with FDTD.
Recommended simulation method
FDTD simulations have well defined polarization. For a beam, unpolarized results are obtained by adding the results of 2 orthogonal polarization simulations incoherently using the equation
The derivation of this equation can be found on the Unpolarized beam page.
In the case of a dipole, the results of the three orthogonal polarizations can be added incoherently using the equation