Hi everyone,
I am trying to simulate a nonlinear silicon nitride waveguide in FDTD. But it requires nonlinear refractive index (n2) value to provide in material. Though I know it's a intensity dependent parameter but I want to calculate it theoretically and put the value in simulation, how can I do that?
Is there any equation between waveguide geometry and nonlinear refractive index?
Thanks in advance.
Dear Rifat Nazneen
Please consider using DFT tools to calculate it. For instance, you can use Quantum ESPRESSO by performing a self-consistent-field calculation, followed by calculating optical properties, leading to epsilon 1 (real) and epsilon 2 (imaginary). Then, the refractive index 1 and 2 can be calculated using both epsilon 1 and 2.
Please see : https://ir.library.dc-uoit.ca/bitstream/10155/159/3/McNelles_Phillip_appendixA.pdf
For an example, please consider looking up: Article Local-symmetry distortion, optical properties, and plasmonic...
Best regards,
S. Muhammady
You might also look in the literature. The calculated Kerr constant values often differ by more than 20 % from the actually measured ones. I can see some measured values for silicon nitride here:
https://www.osapublishing.org/DirectPDFAccess/88C05BCA-F354-43F1-B0C133D8F139595A_368292/oe-25-13-15370.pdf?da=1&id=368292&seq=0&mobile=no
Hi Tomasz Michał Kardaś ,
Thank you for your answer. The link is not working. Would you please share the link again?.
Most of the literature measured the Kerr constant by optimizing input power and other parameters. I want to calculate it theoretically so that I can obtain the pump intensity for the waveguide. As the linear index value of SIN is different for my design than the most of literature used, therefore the Kerr constant will be different. Will it be ok to use those measured values for simulation?
Regards
Rifat
Yes. Here it is: https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-25-13-15370&id=368292
Best regards!
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