Re: 1 dimensional photonic crstal

Here we go:

; band diag of Bragg stack

; the high and low indices:
(define-param n-lo 2.89)
(define-param n-hi 3.34)
(define-param w-hi (/ n-lo (+ n-hi n-lo)))

(print "w-hi" "," w-hi "\n")

(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))))
	 
(set! k-points (interpolate 16 (list (vector3 0 0 0) (vector3 0.5 0 0))))

(set-param! resolution 32)
(set-param! num-bands 6)

(run)

Frederic

On Mar 4 2009, Hyma Yalamanchili wrote:

>Hello
>
>Iam trying to find  bandgap for a 1 dimensional photonic crystal.(bragg
>reflector structure)
>I have many doubts in simulating the structure..
>
>1.As Iam dealing with a  1 dimensional structure,how can I specify my
>lattice vectors such that  the structure repeats just in 1
>direction.(i.e if crystal strucutre is periodic in x has to repeat in x
>but not in y and z).. 
>If I specify no-size in y or z direction it doesn't  consider y  at all
> but I  have to specify a length in that direction without the lattice
>repeating...
>Attached is the code that Iam using.
>Please help me
>
>Thanks
>Hyma Yalamanchili  
>
>
>
>
>----- Original Message -----
>From: "F.S.F. Brossard" <[email protected]>
>Date: Saturday, December 13, 2008 8:06 pm
>Subject: Re: [MPB-discuss]
>To: Hyma Yalamanchili <[email protected]>
>
>> Hi Hyma,
>> 
>> MPB does some internal dielectric averaging between boundaries so 
>> that your structure look more realistic. It also means you probably 
>> don't need such high resolution. For me, I rarely had to use a 
>> resolution beyond 16 in x and y for all bandgap calculations. I 
>> didn't see a significant difference with higher res (except a few 
>> %). Also, you can lower your supercell size in z to 8, even for low 
>> index material such as yours.
>> Howevever, you should increase your k-interp to 8 at least to make 
>> sure you get a reasonably accurate bandgap.  
>> Last advice: there is no need to calculate all points of the 
>> reduced Brillouin zone to calculate the bandgap of a simple 
>> triangular lattice with circular air-holes, at least for TE-like 
>> modes (I have rarely looked at TM-like modes). In this last case, 
>> just look at the K and M points of your first and second bands and 
>> also at the intersection between the light cone and the G-K and G-M 
>> directions.
>> Hope this helps,
>> 
>> Frederic 
>> 
>> On Dec 12 2008, Hyma Yalamanchili wrote:
>> 
>> >Hi Frederic
>> >
>> >Attached is the control file which Iam using..
>> >
>> >Thank u so much for  your reply.
>> >I hope my problem gets resolved
>> >
>> >Hyma
>> >
>> >----- Original Message -----
>> >From: Frederic Brossard <[email protected]>
>> >Date: Friday, December 12, 2008 1:13 pm
>> >Subject: Re: [MPB-discuss] efield vs. dpwr, field definition --> 
>> follow>up on old thread
>> >To: Hyma Yalamanchili <[email protected]>
>> >Cc: [email protected]
>> >
>> >> Hi Hyma,
>> >> 
>> >> Could you please let us know your control file? otherwise, it is 
>> >> difficult to know why it takes so much time without asking you a 
>> >> lot of 
>> >> questions first.
>> >> 
>> >> Thanks,
>> >> 
>> >> Frederic
>> >> 
>> >> Frederic Brossard
>> >> Researcher
>> >> Cavendish Laboratory
>> >> J J Thomson Avenue
>> >> Cambridge CB3 0HE
>> >> 
>> >> 
>> >> 
>> >> Hyma Yalamanchili wrote:
>> >> > Hii
>> >> >
>> >> > Iam in the initial stages of learning MPB tool.
>> >> > My work is mainly focused on band gap tuning. 
>> >> > I tried to change the radius every time  before I simulate and 
>> >> find the
>> >> > band gap but as Iam dealing with 3-D structures,its consuming 
>> a 
>> >> lot of
>> >> > time like 4 to 5 hrs for each simulation to run.
>> >> >  Can anybody suggest me a method  to find the radius of the 
>> >> triangular> lattice photonic crystal for a particular band gap 
>> >> using some kind of a
>> >> > loop???
>> >> >
>> >> >
>> >> > Thanks,
>> >> > hyma
>> >> >
>> >> > ----- Original Message -----
>> >> > From: "Steven G. Johnson" <[email protected]>
>> >> > Date: Thursday, December 4, 2008 12:01 pm
>> >> > Subject: Re: [MPB-discuss] efield vs. dpwr, field definition -->
>> >> > follow up	on old thread
>> >> > To: [email protected]
>> >> >
>> >> >   
>> >> >> Your k point is wrong, for one thing.  Maybe you're not 
>> looking 
>> >> at 
>> >> >> a  
>> >> >> band underneath the light line.
>> >> >>
>> >> >> Look at the line-defect.ctl example file included with MPB.
>> >> >>
>> >> >> Alternatively, you may find it easier to rearrange things 
>> into 
>> >> an  
>> >> >> orthogonal supercell.  See:
>> >> >>
>> >> >> http://article.gmane.org/gmane.comp.science.photonic-bands/1376
>> >> >> http://article.gmane.org/gmane.comp.science.photonic-bands/1213
>> >> >>
>> >> >> Steven (with a v)
>> >> >>
>> >> >> On Dec 4, 2008, at 12:10 AM, Chad Husko wrote:
>> >> >>
>> >> >>     
>> >> >>> Stephen,
>> >> >>> I spent a little more time with the fields and have some 
>> follow 
>> >> >>>       
>> >> >> up  
>> >> >>     
>> >> >>> questions (on the bottom).
>> >> >>>
>> >> >>> First, some answers to yours. I will be using the proper 
>> >> >>>       
>> >> >> definition  
>> >> >>     
>> >> >>> of the effective area as you suggest. I am sure that there 
>> is 
>> >> an 
>> >> >>>       
>> >> >> Ex  
>> >> >>     
>> >> >>> field. The propagation direction is x of the PhCWG. z is the 
>> 
>> >> >>> vertical super cell and y is the direction of sqrt(3)*a of 
>> the 
>> >> >>>       
>> >> >> air  
>> >> >>     
>> >> >>> holes. Attached is the CTL file.
>> >> >>>       
>> >> >> _______________________________________________
>> >> >> 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
>> >> >   
>> >> 
>> >
>> 
>> -- 
>> Dr Frederic Brossard
>> Researcher
>> Hitachi Cambridge Laboratory
>> Cavendish Laboratory
>> J J Thomson Avenue
>> Cambridge CB3 0HE
>> 
>> 
>> 
>> 
>> 
>

-- 
Dr Frederic Brossard
Researcher
Hitachi Cambridge Laboratory
Cavendish Laboratory
J J Thomson Avenue
Cambridge CB3 0HE
Tel: 01223 442 932