Menu

Discussion Forum

New Discussion
Filter

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

width of PML

Posted Jun 15, 2012, 1:15 a.m. EDT 6 Replies

Md. Samiul Habib
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam


What will be the width of the PML( circular) to determine the confinement loss in hexagonal pcf.

Regards
Md. Samiul Habib
6 Replies Last Post Feb 5, 2013, 4:59 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jun 15, 2012, 4:51 a.m. EDT
Hi

I would say a few (<10) wavelength of air, then 2-3 for the PML distance. but I havent modelled optics and fibre for some time, others out here might have better rule of thumbs

--
Good luck
Ivar
Hi I would say a few (
Alexander Kuznetsov
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jun 15, 2012, 12:40 p.m. EDT
First, make PML very large. Then gradually decrease its thickness until your solution starts changing significantly. This way you can find an optimum that's right for you.

If you plan to solve for range of different wavelength, optimize PML for the largest wavelength
First, make PML very large. Then gradually decrease its thickness until your solution starts changing significantly. This way you can find an optimum that's right for you. If you plan to solve for range of different wavelength, optimize PML for the largest wavelength
Md. Samiul Habib
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jun 16, 2012, 10:52 a.m. EDT
Thanx Ivar.
Thanx Ivar.
Farhan Hanaffi
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Feb 4, 2013, 9:27 a.m. EST
how about number of layer ?
how about number of layer ?
Alexander Kuznetsov
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Feb 4, 2013, 7:52 p.m. EST
I always use sweep mesh in PML with 3-5 layers. Again, you can increase the number of layers until you get the desired accuracy.
I always use sweep mesh in PML with 3-5 layers. Again, you can increase the number of layers until you get the desired accuracy.
RVN
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Feb 5, 2013, 4:59 a.m. EST
According to Comsol Support answer I got, it does not matter. The PML will always be "one-wavelength" thick per default, you should just take care how you mesh it. They suggested using mapped-quadratic elements and make sure you have between 1-10 elements across the thickness of the PML. In my experience 4-6 usually is more than enough and I have never had any real need of 10 elements, the marginal computational accuracy vs. the time it takes to compute is not worth it.


Hope this helps
--
/RVN
According to Comsol Support answer I got, it does not matter. The PML will always be "one-wavelength" thick per default, you should just take care how you mesh it. They suggested using mapped-quadratic elements and make sure you have between 1-10 elements across the thickness of the PML. In my experience 4-6 usually is more than enough and I have never had any real need of 10 elements, the marginal computational accuracy vs. the time it takes to compute is not worth it. Hope this helps -- /RVN

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content