Learning Forum

[Seyed Mohammadhossein Enjaviarsanjan]

I have a question regarding the coupling of a nanobeam photonic crystal resonator with a nearby bus waveguide using the side-coupled approach. Is it possible to use the EME solver in this case?

Furthermore, I am interested in measuring the quality factor in the transmission spectrum of the bus waveguide. The intrinsic quality factor of the resonator is over 1 million, so I'm wondering which solver would work better for this scenario: FDTD or EME?

[Guilin Sun]

This will depend on the photonic crystal: if the unit cell is rectangle, or other geometry with much less change in shape like a circle, you may try EME. Otherwise, FDTD might be more efficiet, in particular when the source is broadband.

Quality factor can be measured with relatively short simulation time in FDTD, as shown in online examples. EME is a frequency-domain method. If you want broadband and calculate Q from transmission, you can, by sweeping the wavelength using the built-in wavelength sweep, provided the mode properties do not change significantly over the spectrum. However whether it can actually find correct Q over million will depend on several factors.

 

[Seyed Mohammadhossein Enjaviarsanjan]

My nanobeam photonic crystal consists of periodic rectangle cells, each containing elliptical-shaped holes.

Does it work?

[Guilin Sun]

If you can use sufficient number of cells to well resolve the sllipical holes, you can try. Anyway, since you only simulate one perioid at each side of the cavity, it may work well. However, FDTD will needs to simulate the whole device. So you may try and see which one is more efficient with reasonable accuracy.