Asymmetric TOD laser has unwanted initialisation behaviour

[JessicaTiebel]

I wanted to use a laser with third order dispersion, which should and does produce an asymmetric laser in the longitudinal direction. But using the DispersivePulse incidentField profile the maximum of the pulse is set to be in the centre of the initialisation time. Due to the asymmetry of the laser and the periodicity of the FT used to calculate the laser profile, an edge is formed in the envelope. In the attached picture you can see what I mean.

As an example a simulation with:

• TOD: 4500 $\mathrm{fs}^3$
• GDD: 350 $\mathrm{fs}^2$
• PULSE_DURATION_SI: 30.0e-15 / 2.354820045
• PULSE_INIT: 20
• $\Delta t $: 1.39e-16 * 0.523427 s

[steindev]

So what you are asking for is a parameter to shift the maximum away from the center of the initialization time interval?

That is easy to implement, as the parameter in principle already exists. One just needs to add an extra shift and expose this extra shift as a parameter of the laser profile. Easy for you to do!

See (

picongpu/include/picongpu/fields/incidentField/profiles/DispersivePulse.hpp

Line 233 in 05822d5

float_X const timeDelay = mue + focusPos / SPEED_OF_LIGHT;

)