Maybe to add to the discussion: The behavior in the 2-dimensional case is as expected. There the (run-te) modes have Hx=Hy=0 and the (run-tm) modes have Ex=Ey=0 (as expected!).
Could it be that mpb is using the other convention in 1-dimensional calculations? For the record the version I use is: MIT Photonic Bands 1.4.2, Copyright (C) 1999-2001 by MIT. Using libctl 3.1 and Guile 1.8.7. Running on Ubuntu 10.04.1 LTS Regards, Fitzgerald On Fri, 17 Sep 2010 13:19:14 +0200, <[email protected]> wrote: > I also think I am doing something wrong. Would you be so kind to point me > where the mistake is? > > I am modeling a planar waveguide which has a finite thickness in the > z-direction and is infinite in the xy-plane. To model this I use a > one-dimensional computational cell along the z-direction and look for the > propagation in the x-direction. > > Now for the polarization/symmetry part: > TE polarization has the electric field confined to the xy-plane. > The electric field is given by > Ey(x,z,t) = Em(z) * exp[i(w*t-k*x)] > Hx and Hz are simple functions of Ey. Also, Ex = Hy = Ez = 0. > > TM polarization has the magnetic field confined to the xy-plane. > The magnetic field is given by > Hy(x,z,t) = Hm(z) * exp[i(w*t-k*x)] > Ex and Ez are simple functions of Hy. Also, Hx = Ey = Hz = 0. > > Em(z) and Hm(z) are the mode profile functions and are even for m = > 0,2,4,... and odd for m = 1,3,5,... > > > When I now run the .ctl file given below with (run-te), (run-tm); MPB > outputs zevenfreqs and zoddfreqs. When I look at the fields at k = (1,0,0) > I find the following: > 1st zeven - 1st TE mode > 2nd zeven - 2nd TM mode > 3rd zeven - 3rd TE mode > 1st zodd - 1st TM mode > 2nd zodd - 2nd TE mode > 3rd zodd - 3st TM mode > > > Clearly my TE/TM convention is different from the one MPB uses. What is > this other convention? > > Your help is highly appreciated, > Thanks in advance, > > Fitzgerald > > > ;========================================================================== > > ; define geometry > (set! geometry-lattice (make lattice (size no-size no-size 10))) > (set! geometry (list > (make block > (material (make dielectric (epsilon 12.1))) > (center 0 0 0) > (size infinity infinity 1) > ) > )) > > ; define sample space > (set! k-points (interpolate 49 (list (vector3 0 0 0) (vector3 1 0 0)))) > > ; define simulation resolution and bands > (set! resolution 256) > (set! num-bands 3) > > (run-te (output-at-kpoint (vector3 1 0 0) output-efield output-hfield)) > (run-tm (output-at-kpoint (vector3 1 0 0) output-efield output-hfield)) > > ;========================================================================== > > > > > > > > On Fri, 17 Sep 2010 01:45:18 -0400, "Steven G. Johnson" > <[email protected]> wrote: >> On Sep 16, 2010, at 5:44 AM, <[email protected]> <[email protected]> wrote: >>> I am trying to calculate the dispersion diagram for a photonic slab >>> waveguide. For this I use a 1-dimensional computational cell in the >>> z-direction. The waveguide itself is in the xy-plane and has a >>> thickness of >>> 1. In the attachments you find the Scheme file I used and a simple >>> bash >>> script with the commands I used to execute it. >>> >>> What I expected: >>> (run-zeven) yields bands TE0, TE1, TE2, ... >>> (run-zodd) yields bands TM0, TM1, TM2, ... >>> >>> What I found: >>> (run-zeven) yields bands TE0, TM1, ... >>> (run-zodd) yields bands TM0, TE1, ... >>> >>> What am I doing wrong? >> >> Probably you are just confused because there is more than one >> convention for "TE" and "TM" in the literature. The TE you are >> probably thinking of corresponds to run-yodd and the TM you are >> probably thinking of corresponds to run-yeven. >> >> The key thing is to figure out what is transverse to what in your TE/ >> TM convention, and what symmetry that corresponds to. (See chapter 3 >> of our photonic-crystals book, ab-initio.mit.edu/book, to understand >> how polarization corresponds to symmetry.) >> >> --SGJ >> >> >> _______________________________________________ >> mpb-discuss mailing list >> [email protected] >> http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss > > > _______________________________________________ > mpb-discuss mailing list > [email protected] > http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss _______________________________________________ mpb-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/mpb-discuss
