FDTD modeling of a Gaussian Laser Source

Hi,

First time post here and a bit of a desperate attempt to get some help with a major hold up in my PhD research.

Basically I am writing FDTD code to analyse the effects of laser light through small apertures used in new HAMR technology. I am writing the code in Matlab and have just got to the point where i am attempting to insert a plane wave incident source using TF/SF technique but I want it to have a Gaussian shape profile like that of a typical laser in optical systems.

Does anybody out there have any suggestions or code that would help me achieve this. I have been through many papers and books who all seem to uses the same approach within certain extents but none have came up with a definitive answer. I am using a transverse electric approach in 2D at the moment and can implement a plane wave but when it comes to applying a Gaussian shap function it all goes wrong!!

Any help at all would be appreciated.

Thanks

Dan

reading the sentence "i am attempting to insert a plane wave incident source using TF/SF technique but I want it to have a Gaussian shape profile", I think you should differentiate the two concepts: Gaussian Beam v.s. Uniform Plane Wave. Sometimes people call the Gaussian beam a plane wave because it has uniform phase on the focal plane. On the other hand, a (normal) plane wave should have both uniform phase and amplitude. (let's forget the evanescent plane wave for this discussion.) So what you need to insert is not A plane wave, but rather a whole spectrum of plane wave.

Since you didn't mention what goes wrong, I would suggest that you first check the propagation of the Gaussian beam in a homogeneous medium. Does the field propagate like a Gaussian beam? If not, give us some details on how you are implementing it. How is your "same" approach different from others? Why you said that nobody has a definite answer?

Also, you can find Gaussian beam in some commercial code (OptiFDTD-if I remember correctly).

have at look at Online Papers at www.t-matrix.de.
There you will find some papers on how to implement the Gaussian
beam into verious scattering theories.