Discussion Forum

Hi.
I am trying to simulate propagation through single-mode optical fiber. The incident field is assumed to be a Gaussian beam, whose parameters (beam waist, Rayleigh range, beam intensity) are defined in Parameters section. I use matched boundary condition on the bottom end of the fiber where the light is coupled (see Fig.1); the equation for Gaussian beam is specified in the incident field section (see Fig.2, z - direction of propagation). I use electromagnetic field beam envelope interface and wavelength domain study step.
Actually I need to calculate transmission as a ratio of Power transmitted/input Power. In doing that I faced with the problem when output power is of order 10^-20 which does not make sense. In order to compute power I use integration over the input boundary and over the output boundary, where input boundary is the light coupling area, output is the surface where light is come out (see Fig. 3).

Did someone face this problem? Do I need to specify matched boundary condition at the upper end of the fiber? Maybe I missed some important boundary conditions (see Model builder screen attached)...

Any suggestions will be highly appreciated.
Thank you in advance.
Alexandra.