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Attenuation Constant for waveguide
Posted 09.12.2015, 12:01 GMT-5 RF & Microwave Engineering Version 5.1 2 Replies
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Hi,
I try simulate rib waveguide with silicon as a substrate, lower cladding silica, core glass and upper cladding air in order to find attenuation constant with respect to the lower cladding thickness. However, when I try simulate it, it seems that attenuation constant become lower as lower cladding is thinner. This is not true. Can anyone advice me, which step that trigger this problem?
Thank you
I try simulate rib waveguide with silicon as a substrate, lower cladding silica, core glass and upper cladding air in order to find attenuation constant with respect to the lower cladding thickness. However, when I try simulate it, it seems that attenuation constant become lower as lower cladding is thinner. This is not true. Can anyone advice me, which step that trigger this problem?
Thank you
2 Replies Last Post 16.12.2015, 06:39 GMT-5
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Posted:
9 years ago
Hi Suraya,
I am not familiar with your exact configuration, however generally for waveguides following are valid: Attenuation can arise form radiative leakage and form internal losses in material.
If your mode does not have radiative leakage than the internal losses are the only mechanism. Than as higher the mode confinement is, the higher is attenuation.
Check also that your domain is big enough to contain all the fields inside, and you do not have losses due to the scattering BCs of PMLs.
One common mistake is the definition of the internal losses. Comsol uses the time convention ext(iwt), hence negative imaginary part of the refractive index results in losses, whereas positive in gain.
Best regards,
Maxim
I am not familiar with your exact configuration, however generally for waveguides following are valid: Attenuation can arise form radiative leakage and form internal losses in material.
If your mode does not have radiative leakage than the internal losses are the only mechanism. Than as higher the mode confinement is, the higher is attenuation.
Check also that your domain is big enough to contain all the fields inside, and you do not have losses due to the scattering BCs of PMLs.
One common mistake is the definition of the internal losses. Comsol uses the time convention ext(iwt), hence negative imaginary part of the refractive index results in losses, whereas positive in gain.
Best regards,
Maxim
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Posted:
9 years ago
Dear Maxim,
Thank you.
Regards,
Suraya
Thank you.
Regards,
Suraya