Learning Forum

[Fatemeh]

Hello Lumerical team,

I have a very simple structure including a core and cladding. When I use metal as BC the effective refractive index of the modes are pure real values and when I use PML as BC on both sides in the y-direction the effective refractive index becomes complex but the imaginary part is very small. I would appreciate it if you could tell me why n_eff becomes complex when using PML. Please see the figure below. Also, why there is an error that says "row1: invalid periodic group" as seen in the figure?

 

Thanks

 

[Kyle]

Hello,

The PML boundaries at several layers of absorbing material to the borders of the simulation region to absorb the light exiting the simulation region. This absorbing material is what makes the effective index complex. For waveguide modes confined to the waveguide core, this absorption is negligible and can be ignored. Moving the boundaries away from the waveguide core should reduce this artificial absorption.

[Fatemeh]

Thank you Kyle!

[namratah]

Hey,

CAN ANYONE HELP ME WITH THE EXTRACTION OF PARAMETERS (REFRACTIVE INDEX) FROM S PARAMETERS FOR A INHOMOGENEOUS METAMATERIAL?

 

PLEASE HELP ME WITH IT.

@Ansys Innovation Space Help

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