A version for CW?

[DreamingWater]

could you provide a version for CW, I do not know how to fix it to CW SHG.

[NickKarpowicz]

Hi there! If you want to do CW propagation in the unidirectional pulse propagation mode, I'd suggest the following:

• Use a value of the time span which is twice the period of the fundamental wavelength (it has to be at least twice for technical reasons, but you can choose any integer >1 times the period)
• Choose a value of the pulse energy that corresponds to the energy of your CW beam in this time window (i.e. if you have a 1 kW beam, and a time window of 10 fs, the energy is 1 kW * 10fs = 10^-11 J).
• Set the bandwidth to a very small number.

I attached a demo calculation in BBO, doing second harmonic of a 200 THz (~1.5 micron) laser. It's done in 3D so you can see the effect of spatial walk-off.

Does this make sense for you?

This works because in the UPPE mode, the time grid is periodic, so a CW beam with matching periodicity will propagate correctly. It will be trickier if you want to use the FDTD mode, since that requires a beginning and end time of the field...

Cheers, Nick Test_CW_SHG.zip