On Sat, 20 Oct 2007, adrian wrote: > I'm wondering the definition of complex fields. > Typically, in time domain, E(r,t)=E(r)cos(wt). But how about the > complex fields? > Are they just simply represented as E(r,t)=E(r)exp(-jwt) or something > else?
Either real or complex fields can be any function of time, depending on the sources. However, if you put in a time-harmonic source, a continuous-wave source in Meep, then the time dependence should be asympototically exp(-iwt) for a frequency w. > In addition, how to find out the eigen mode? In tutorial, one just > exited one resonant mode and saw the field pattern. However, if the > input is continuous, then the field pattern will include the source > itself. So I don't think that field pattern is real eigen mode. But if > one just turned off the source and record the field pattern after a > couple of periods, then the field will decay with time, if so, how do we > get the exact spatial distribution of eigen mode? More specifically, how > can we separate the time argument from the field pattern? Put in a narrow-band gaussian pulse and look at the field pattern when the pulse has turned off. Even if you have a resonant mode, assuming it is sufficiently long-lived then you should still have the field pattern (multiplied by the decay coefficient). As long as the pulse source is narrow-band enough, no other modes should be excited significantly. Regards, Steven G. Johnson _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
