Learning Forum

[Brian West]

I'm trying to convert a subwavelength grating waveguide into an effective medium waveguide (with no variation along the propagation direction).  The standard laminar approximation to determine the anisotropic effective medium matrix elements (nxx, nyy, nzz) is easy to code, but I'm not close enough to this regime for the results to be very accurate.  I'm wondering if there is a good way to extract these elements using FDTD and possibly RCWA.  Thanks.

[Guilin Sun]

I believe this might be more theoretical than simulation.

If this device can be simulated, it is better to get simulation result, instead of approcimation.

If case it cannot be simulated due to device size, and you want to build up a new model with its effective index, care should be taken: You will need to validate the effectiveness of this method from a simple case.  Usually the effective material parameters are extracted through S parameters, or reflection/transmission, and most likely the result is polarization dependent.

You may refer to this example, which is isotropic: Metamaterial parameter extraction - Smith

[Brian West]

Thanks...that example seems to be relevant, but I can't figure out how to get it to work with my geometry.  Can we possibly work on this offline?

[Guilin Sun]

If it is such modified metamaterial, you can directly use this method to extract the effective material peoprties, regardless its geometry. If it has substrate, you will need a second simulation to get S12 and refer to Smith's paper to use another formula, as the example is for symmetry case.

Basically it is based on amplitude transmission/reflectio coefficent to retrace the effective data.  You can also refer to the Fresnel coefficients for a cavity.

I am not sure what do you mean offline. Depending on your license type, it may work without internet connection. You can download the example file and save on to your local machine.

 

[Brian West]

I just meant, can you and I discuss this problem outside of the Forum?

[Guilin Sun]

 

You can send us support email if you have the premium support privilege. You may also try in the Feed if you cannot send email. But you need to let me know the feed link as the feed is private that I cannot directly access., without forum admin to let me be there.