; Compute the bands at the X point for a quarter-wave stack Bragg; mirror (this is the point that defines the band gap edges).; the high and low indices:(define-param n-lo 1.0)(define-param n-hi 3.0)(define-param w-hi (/ n-lo (+ n-hi n-lo))) ; a quarter-wave stack(set! geometry-lattice (make lattice (size 1 no-size no-size))) ; 1d cell(set! default-material (make dielectric (index n-lo)))(set! geometry       (list       (make cylinder 	 (material (make dielectric (index n-hi)))	 (center 0 0 0) (axis 1 0 0) 	 (radius infinity) (height w-hi))))(define-param kx 0.5)(set! k-points (list (vector3 kx 0 0)))(set-param! resolution 32)(set-param! num-bands 8)(run-tm) ; note that TM and TE bands are degenerate, so we only need TM