How to create MgO:LiNbO3 diffusion profile?

[Mubarak Ali]

Hi..

I try to create a waveguide in MgO doped lithium niobate, but it shows error as “Too low refractive index contrast”. I also tried to using the dopant concentration(Cm) formula for Magnesium. It would be great help if someone clarify this error. Thanks in advance…

[Steve Dods]

We have been unable to reproduce this issue at Optiwave. Can you send us a project that creates this error message?

[Mubarak Ali]

Hi.. Here is the file..

Attachments:

1. cps_mgo_v3_r1.bpd

[Steve Dods]

Thank you for sending the sample project file. Now I can clearly see the problem. These waveguides have been formed with a Mg stripe evaporated to lithium niobate. Magnesium diffusion causes the refractive index of LiNbO to become less, not greater. Therefore these stripes have refractive index less than the substrate. Therefore there is no mode. You ask for modal input. The mode solver fails to find it because it doesn’t exist. There will be an error message indicating a problem with mode solving. try using Titanium diffustion, instead of Magnesium!

[Mubarak Ali]

Hi Steve Dods..

Thank you for your great answer. I have found in a sample file of OptiBPM ie. Magnesium doped waveguide is placed on top of the Titanium doped lithium niobate. The waveguide model is working, but the output electric field is decreasing in magnitude if we increase the length of the waveguide. I also tried to configure as directional coupler, but there is no coupling between two waveguides. We are mainly focusing on MgO:LiNbO3 wafers to develop our optical devices, hence I require this Mg doped LN waveguide.

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