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
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