How to set k-points in piperiod pc waveguide?

 Dear Steven and MPB's users:


 

  I design a PC waveguide ,  the period of waveguide is not equal to the period of crystal . The edge of Brillouin zone of cyrstal is K'=(0.5pi/a 0 0) along the direction of waveguide. The edge of Brillouin zone of waveguide is K'=(pi/a 0 0). I think that if we use K'=(0.5pi/a 0 0), the mode of crystal which isnot in gap will resemble the normal mode of crystal single period waveguide,and the mode in gap will be folded. if we use K'=(pi/a 0 0), the mode of crystal which isnot in gap will be symmetrical about the K'=(0.5pi/a 0 0), and the mode in gap will not folded. But from the band map ,It seem to two "K'" isnot right. what is the reason? 
So, When i calculate the mode of  the waveguide , how to define the k-point ,K'=?

the structure of  PC  waveguide:
 
 *   *   *   *   *   *   *   *   *   *   *   *   *    *    *   *   *
 *   *   *   *   *   *   *   *   *   *   *   *   *    *    *   *   *       
 *   *   *   *   *   *   *   *   *   *   *   *   *    *    *   *   *       
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 *   *   *   *   *   *   *   *   *   *   *   *   *    *    *   *   *
 *   *   *   *   *   *   *   *   *   *   *   *   *    *    *   *   *
 *   *   *   *   *   *   *   *   *   *   *   *   *    *    *   *   *

My ctl 

 (define-param h  0.5) ; widelength of  waveguide
 (define-param r 0.3)  ;
 (define-param rd 0.2)

 (define-param eps 1)
 (define-param supercell-y (+ 8 h))

 (set! default-material (make dielectric (epsilon 11.56)))

 (set! geometry-lattice (make lattice 
    (basis1 1 0)
    (basis2 0 1)
    (size 1 supercell-y no-size)))

(set! geometry (append
                      (list (make block (center 0 0 0)(size a supercell-y no-size)(material (make dielectric (epsilon 11.56)))))

(list (make cylinder (center 0 (+ (/ h 2)  0.5 ))(radius rd)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  -0.5 ))(radius rd)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0.5 (+ (/ h 2)  0.5 ))(radius rd)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0.5 (+ (/ h 2)  0.5 ))(radius rd)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  1.5 ))(radius r)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  -1.5 ))(radius r)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  2.5 ))(radius r)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  -2.5 ))(radius r)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  3.5 ))(radius r)(height infinity) (material (make dielectric (epsilon 1)))))
(list (make cylinder (center 0 (+ (/ h 2)  -3.5 ))(radius r)(height infinity) (material (make dielectric (epsilon 1)))))))
  
(define Gamma (vector3 0 0 0))

(define K' (lattice->reciprocal (vector3 ? 0 0))) 
(set! k-points (interpolate 19 (list Gamma K')))

(define-param extra-bands 2)
(set! num-bands (+ 9 extra-bands))

(define-param res 32) 
(set! grid-size (vector3 res (* res supercell-y) 1))

(run-te (output-at-kpoint K' fix-hfield-phase output-hfield-z))


To Administrator 

    I have send out the article with the same title , 
 How to set k-points in piperiod pc waveguide? Fri, 20 Feb 2009 01:03:32 -0800
but it was shown by error. Would you delete the article? Thanks




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