I would like to calculate a sensitivity of a Si waveguide by using a formula= change in effective refractive index/change in sample index.
I modeled my design in COMSOL in wave optics (ewfd) and use mode analysis. Can anyone tell me the proper method to calculate the sensitivity of a WG? or if anyone has COMSOL file related to this simulation?
Your help will be appreciated.
Once you have made the simulation in the COMSOL (the one you are talking about, I assume you made a 2D simulation with air and silicon oxide as cladding materials), you can find out the effective refractive index of the silicon waveguide.
In the mode analysis tab, go to setting, and then study setting.
1) Select the number of modes you want to find out. Usually it is 6 by default.
2) Have the mode selection frequency i.e., the mode analysis frequency where you want to have the readings (for Si you may be using, 1300nm or 1550nm lasers, so have the value of the frequency for these wavelengths).
3) Then, select the "search the modes around" value. This value is the refractive index of your waveguide i.e., silicon for your case, which is 3.44 or whatever value you are using.
4) Transform : Effective mode
5) Search Method: Manual
6) Mode search method around shift: Closest to absolute value
Now run the simulation.
You will the results.
The results will be six different effective refractive index values your waveguide will be supporting. The effective refractive index will be different for each mode. From there you can easily find out which propagating mode is present for your structure and what exactly is the effective refractive index.
Usually in integrated optics where you can have 500nm wide and 250nm thick Si waveguide, you will get both TE and TM mode propagating the waveguide with effective refractive index of around 2.45 and 1.79 for oxide (n = 1.45) and air (n = 1) as cladding materials.
Once you have a basic simulation ready, you can tailor it for any material, cladding, and dimensions you want.
Happy simulations :)
I suggest to you CUDOS software which compute the neff by a simple way and you can use the curve fitting in co-operate with the software for more accurate results.
Hello,
You also can check this option:
https://www.rp-photonics.com/effective_refractive_index.html
Hello,
Have a look on this paper under title "Sensitivity Analysis and Uncertainty Mitigation of Photonic Integrated Circuits".
May be it is helpful. In the paper I am calculating the sensitivity indices (Si and STi) of filter parameters when there is a uncertainty in the waveguide width and gap of the coupler. In the appendix of the paper you will find two methods to calculate the Si
For the subject reason, uou can use following software (i have used the them personally)
FIMMWAVE (Commercial)
Opto Designer (Commercial)
MATLAB mode solver (Free for academics)
BeamProp (I think you can find the free version of it)
Let me know if you need any other help in this regard
Once you have made the simulation in the COMSOL (the one you are talking about, I assume you made a 2D simulation with air and silicon oxide as cladding materials), you can find out the effective refractive index of the silicon waveguide.
In the mode analysis tab, go to setting, and then study setting.
1) Select the number of modes you want to find out. Usually it is 6 by default.
2) Have the mode selection frequency i.e., the mode analysis frequency where you want to have the readings (for Si you may be using, 1300nm or 1550nm lasers, so have the value of the frequency for these wavelengths).
3) Then, select the "search the modes around" value. This value is the refractive index of your waveguide i.e., silicon for your case, which is 3.44 or whatever value you are using.
4) Transform : Effective mode
5) Search Method: Manual
6) Mode search method around shift: Closest to absolute value
Now run the simulation.
You will the results.
The results will be six different effective refractive index values your waveguide will be supporting. The effective refractive index will be different for each mode. From there you can easily find out which propagating mode is present for your structure and what exactly is the effective refractive index.
Usually in integrated optics where you can have 500nm wide and 250nm thick Si waveguide, you will get both TE and TM mode propagating the waveguide with effective refractive index of around 2.45 and 1.79 for oxide (n = 1.45) and air (n = 1) as cladding materials.
Once you have a basic simulation ready, you can tailor it for any material, cladding, and dimensions you want.
Happy simulations :)
"Integrated Photonics" by Michal Lipson and "Silicon Photonics Design" by Chrostowski are two good text books if you want to perform numerical calculations by hand.
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