Ansys Insight : Visualize the CW response of a plasmon mode

trobertstroberts Ansys Employee Posts: 2
edited February 23 in Photonics

To create a movie of the CW response we have a feature called the phase shift animation.

  1. Select the E, H or P result.
  2. Visualize one of the components X, Y, or Z.
  3. Open the figure settings and scroll to the bottom. Enable the “Phase shift animation”
  4. Set the FPS frames per second, and frames per cycle, I find that 32 frames per cycle and 25 fps works well.
  5. Export as an .mpeg or .avi movie.

The vast majority of devices are passive and meant to operate in Steady-State. Such devices are examples of Linear Time Invariant systems, and it is sufficient to simulate the transient response of such systems to completely characterize the frequency response. FDTD does this very efficiently, and without approximations, allowing one to export the frequency dependent S-parameter for further circuit simulations. From a data analysis standpoint this is enough, but it is also important to communicate your ideas, and build intuition. These CW plots do precisely that which make them an interesting feature that I believe many users will enjoy working with.

Previously this was only possible through a multi-step process using MATLAB. Now it is trivial to do from the visualizer. Effectively the field components are multiplied by a complex phase factor in each frame. This is an accurate depiction of the CW response provided the Fourier Transform is valid.

Example

In the AppGallery example Plasmon Mode Excitation 7 they demonstrate how to excite the plasmon modes of an Au nanoparticle dimer.


Referring to [1] they lead off by stating

The plasmon hybridization model of electromagnetic coupling between plasmonic nanoparticles predicts the formation of lower energy “bonding” and higher energy “antibonding” modes in analogy with the quantum mechanical description of chemical bonding

These dark modes do not radiate very efficiently nor are they readily excited by normal light. The dipole moments of these plasmon modes cancel out due to their anti-bonding characteristics. Bonding, or bright, modes correspond to modes that can be easily excited by linearly polarized light as the dipoles oscillate in phase. This is all very interesting, but wouldn’t it be nice to quickly visualize these dark modes?

Figures


Fig1: Ex Component of the out of phase anti-bonding dark mode at 500nm, excited by a radially polarized beam.



Fig 2: Ex Component of the in phase anti-bonding of a dark mode at 700nm, excited by an azimuthally polarized beam.

References

  1. Dark Plasmon Modes in Symmetric Gold Nanoparticle Dimers Illuminated by Focused Cylindrical Vector Beams 2J. Phys. Chem. C 2018, 122, 48, 27662-27672


Sign In or Register to comment.