I have a very simple question. How could I define a source Gaussian out from a single mode fiber, which core size is 4 micro, NA =0.12. I know the beam size (diameter) should be set to be MFD, how to put the parameter for position? should I put the parameter of the position as Rayleigh distance Zr? or should I use MFD/(2*NA)?
Thanks for your answer in advance.
Best answer by BilyboyView original
In the manual, it says that
Position: The distance from the apparent point of divergence of the rays to the source plane location. If zero, the rays are collimated. A positive Position value means that the apparent point of divergence is located in the negative Z direction relative to the vertex of the source plane.
The angular distribution of the source is determined using the Beam Size (parameter 6) and Position (parameter 7) to calculate the far-field divergence angle of the source. However, the physical size of the beam as given by the Beam Size is not used, as the size and spatial distribution of the source is neglected.
So I think the position should be defined as MFD/2/NA.
Please comment if you are an expertise.