Photonics

Photonics

Isotropic source in FDTD energy conservation problem

    • refetali
      Subscriber

      Hello,

      Normally I have an isotropic emitting source. To represent it by dipoles I followed the link below and run the simulation for 3 three diferent(orthagonal) direction and took average of them.

      forum.ansys.com/discussion/25573

      The size of the monitor is not infinite so instead of observing 0.5 transmittance and 0.5 reflectance I observed 0.41 and 0.41 which is ok. When I widen the monitor size and/or get two monitors close to each other these numbers converge to 0.5 which makes sense.


      When I put an aluminium nano-antenna above the emitter, I observe such reflectance and transmittance values which seems unphysical to me. Since there is no fluorescence effect in the process, R+T should not exceed 1 but even R itsself exceeds. I put lsf code that creates the model. Could you check where the problem is?


      Thanks !

    • Taylor Robertson
      Ansys Employee

      The amount of power a dipole emits in a infinite homogenous medium is what is used to normalize the power. If you have an antenna near the dipole then this will change how the dipole radiates, which can cause the power to exceed 1. The ratio between the power radiated by the source in the simulation and an isolated dipole is defined as the Purcell factor and is real physical phenomenon. If you are simply looking to normalize to the actual injected power you can use the dipolepower script command. See the following articles for a discussion on this topic.
      https://support.lumerical.com/hc/en-us/articles/360041612594
      https://support.lumerical.com/hc/en-us/articles/360034382834
      Best
Viewing 1 reply thread
  • You must be logged in to reply to this topic.