Photonic Lantern


#1

Hi everyone,

I want to develop a photonic lantern in lumerical and I think the best product for development is MODE solutions. Is this correct? Also, any thoughts on how this might be accomplished? My current approach is to design a N-mode multimode fiber/waveguide (where N=4), determine where the modes are spatially in the multimode fiber/waveguide, then place single fibers at those positions.

https://www.osapublishing.org/aop/abstract.cfm?uri=aop-7-2-107

Any thoughts?
Joe


#2

Dear @jkoehl

Yes, MODE solver should be just fine for these simulaitons. Based on Fig. 6 of the paper, you can use EME for the transition part and FDE for overlap calculations between MMF and SMF fibers (to find the optimal SMF locations). The links below should be a good place to look at for how to calculate modes of PC fiber:

https://kb.lumerical.com/en/index.html?pic_passive_fibers_pc_bragg.html
https://kb.lumerical.com/en/index.html?pic_passive_fibers_pc_fiber_asap.html

Please go ahead with the design and I am glad to be of a help.

Thanks


#3

Hi bkhanaliloo,

It looks like I’ll need to extract the s-parameters of the PL as I need to use them in an interconnect simulation I’ve created. Is the FDTD solution a better route for this?

Thanks
jkoehl


#4

Hi @jkoehl

You can use MODE to extract s-parameter:

https://kb.lumerical.com/en/index.html?pic_passive_getting_started_ring_resonator_mode2.html

Also, even if you finally decided to use FDTD, I think it is a good idea to start with MODE and then use FDTD as a sanity check when your design is finalized.

Thanks


#5

Sounds good, I’ll stick with MODE then!

Thanks,
Joe


#7

Hi @bkhanaliloo,

Final got around to the modeling this PL again. I’m trying to create a movie using FDTD, but I’m not able with how I’ve set things up. I’ve been following a few examples from the forums, particularly https://kb.lumerical.com/en/ref_sim_obj_source_movies.html. Unfortunately, I can’t get a movie to work. Any chance someone could at why? I only a small blip of the mode source, when I’d like to see it propagate the length of the PL.

Thanks,
Lantern_test.lms (505.9 KB)
jkoehl


#8

Dear @jkoehl

Sorry for any inconvenience.

Movie monitor can be used only in FDTD or varFDTD. Looking at your simulation file in MODE, you had only FDE and EME as available simulation type to choose from.

Can you please explain in more details on what you want to do? and provide the simulation file.

Thanks


#9

@bkhanaliloo,

Sorry, i attached the wrong file… it was late at the time. Here is the FDTD file: lantern_Test.fsp (6.3 MB)

I would just like to create a movie (or some type of evidence) that shows that the light is propagating along the length of the structure.

jkoehl


#10

@bkhanaliloo,

To be more clear, I want to eventually extract the s parameters of a working photonic lantern to create a custom module in INTERCONNECT.

jkoehl


#11

Dear @jkoehl

Thanks for additional info and sharing the simulation file.

I understand why the use of movie monitor is challenging in your case. You are performing a 3D simulations with 4 fibers in which one of them is located at the center of the simulation region and the other three are positioned with 120 degrees from one another:

Movie monitor can record transmission only on a 2D plane with normal vectors along x,y, or z axes. This means that you will not be able to watch transmission in all 4 fibres with a single movie monitor and you will need a few of them. If you have any questions regarding setting up the movie monitor, please let me know.

Sometime using profile monitors might be as useful as movie monitors to obtain light propagation with the benefit of reducing simulation time significantly as opposed to movie monitors.

Also regarding your simulation file, I do not think that you can employ any symmetry to your simulation, except maybe along the z-direction. You have a cone shape clad and fibers are located on triangular corners. Also, you need to use PML boundary conditions instead of metal so that light is absorbed at the boundaries of simulation region.

I also recommend to use DFT monitors at the end of each fiber to study transmission on each branch. Once that you obtained reasonable transmission, which indicates that you have set your simulation file properly, you can add movie monitors to study light propagation.

I hope this was helpful, and please let me know if you have further questions.

Thanks