Eigenmode sources for Hz polarization

[ianwilliamson]

Currently get_modes() and insert_modes() only support the Ez polarization. The calculation should be extended with a user toggle to select either the Hz or the Ez polarization.

[rickyim]

Hi, @ianwilliamson @twhughes I implemented a very rough hz waveguide mode calculation (https://github.com/rickyim/ceviche/blob/master/tmps/hz_mode_test.py). But the resulting mode profile does not evanescently decay in the low index medium as expected. It would be of great help if you could point out what might be wrong with the code.

Thanks in advance!

[twhughes]

There are many eigenmodes of the system, most of those will be non-physical. So it takes some effort to find the guided modes you're looking for. The sigma parameter in the eignevalue solver represents a guess for the eigenvalue so the solver can look around there. Rather than sigma=1, you might want to set this closer to the refractive index of the core region, because typically the guided modes have eigenvalues around that.

[rickyim]

Thank you!@twhughes I get it fixed by changing the sigma as well as A.

[twhughes]

Unitless. As in your code

On Sat, Apr 18, 2020, 9:24 PM Rickyim [email protected] wrote:

Thank you!@twhughes https://github.com/twhughes When you say the sigma parameter should be around the core index, what is the scale of the matrix A ?

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[twhughes]

We should implement Hz in the main codebase eventually