Discussion Forum

Dear masters...i have successfully plotted band structure for 2D sonic crystal with comsol. However, it's also worthwhile to study the evanescent modes in lossy materials, this is done by calculating the complex band structure (usually done with an extended plane wave expansion procedure). The complex band structure is calculated by using a real frequency as input and solving for complex wave number. Thus resulting in two dispersion curves, one is omega vs real(k) and one is omega vs imag(k). I learned from a paper that to take wave number(k) as the eigenvalue, one has to apply PDE module. But i really have no idea how could i apply peridoic condition within PDE module as what i do within solid mechanics module. Looking forward to your kind guide! Even if someone has done this within the scope of optics or electronics, it would be helpful.