Hi, Onder, I guess that the tilting trick on the aforementioned page is a good approximation for little angles. For higher angles of tilting, denoted by 'theta' here, a precise solution would require to: * stretch the source envelope by 1/cos(theta), * calculate k_x precisely as cotg(theta), * perform some clever correction on the source amplitude, which I do not dare to guess here. Hope this helps. Filip
2012/12/4, Onder Karakilinc <[email protected]>: > Dear meep users & Dr. Johnson > > > Definition of Gaussian beam source was asked in the forum page and > description was given as the following. > > > http://thread.gmane.org/gmane.comp.science.electromagnetism.meep.general/77/focus=78 > > > " Just provide an amplitude function (amp-func property) that gives the > > field amplitude as a function of space to make a Gaussian envelope. To > > tilt the beam, add an exp(ikx) phase. e.g. do: > > (define ((my-amp sigma k) x) > > (exp (- (* 0+2i pi (vector3-dot k x)) > > (/ (vector3-dot x x) (* 2 sigma sigma))))) > > > > and then create a source with (amp-func (my-amp s k)) where you pass it > > the desired width s and k-vector k. > > (Note that the syntax (define ((foo x) y) ...) defines a function (foo > > x) that returns a function of y.)" > > > > Gaussian beam depend on the radial distance “r”. > > > http://en.wikipedia.org/wiki/Gaussian_beam > > > if 2D structure is taken (in x-y plane and propagation direction is taken > along the x -axis ), r =y > > But I cannot see coordinate” y” in the amplitude function described above. > What is the point I missed or thought wrong? > > > best > Onder > _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
