How can I design a sinusoidal grating?

I’m using a grating coupler for a simulation, but the grating and it’s coating must be in sinusoidal shape.
I tried to change the script of grating but i couldn’t get the right script for it.
In official site of lumerical software, it says that “Diffraction orders for idealized square tooth, sinusoidal, blazed and custom gratings”.
Can anyone help me to design a sinousoidal grating in lumerical by changing the script of grating, using a different grating structure or etc??

Dear @Daniel.vand

This link will be a good place to start:

and see this KB page for making polygons:

My idea is that your grating will be made from three section: one central straight waveguide, and two sinusoidal polygons (on the top and bottom of the central waveguide).

Can you please go ahead with creating the structure and let me know if you have any problem.