How to decide the running time under using continous source?

[beizhixing]

Hi, I want to simulate waveguide by using continous source, it is tricky to set the running time.

The image below are under different simulation time setting:

sum.run(until=400)

sum.run(until=500)

sum.run(until=3000)

I think as long as the simulation convergence, no matter how long I set, the result shoud be not change.

I'd be appreciate if you can help me to solve it, @smartalecH @oskooi !

[stevengj]

What is the scale bar on the third plot? Is the simulation diverging?

[beizhixing]

This is a 2D simulation. The scale bar are default, 1 micromrter.
I do not how to judge whether the simluation converge? But you can see some scattered light when runtime = 3000.

[stevengj]

by scale bar I mean the scale bar for the colors, which you omitted in the third plot

[beizhixing]

The scale bar of the third same as the second plot.

[smartalecH]

Is this just a waveguide? Are you only injecting a single mode?

Do you have proper boundaries layers set up? It looks like you may have some large reflections with the domain edges?

[beizhixing]

Yes, it is just a waveguide by anisotropic materials, refer to https://www.nature.com/articles/nphoton.2016.138. I set all the boundary conditions of PML = 1.0um.