Learning Forum

[Term]

Hi all,

I want to simulate the absorption curve of a substance in the infrared region.

I will write down the condition of the simulation below,

type of simulation: FDTD 3D

there is a sphere whose dispersion follows the imported data I made. Using the Lorentz function, I calculated the refractive index and fabricated the sphere myself. 

I inserted a Gaussian light source and monitored the power of transmittance with a frequency-domain field power monitor on the opposite side.

However, I have not obtained the appropriate results. I couldn't get absorption at a wavelength of 3um.

 

Could you please tell me your advises?

 

Thank you in advance.

 

Best regards

[Guilin Sun]

I am not sure what does this mean "I couldn't get absorption at a wavelength of 3um." do you get absorption at other wavelengths?

For a fixed Gaussian beam, assuming there is no side leakage, the absorption can be calculated as A=1-R-T where R is the reflection.

You can also use a less-accurate method to add a 3D monitor on the sphere, and using script to calculate the absorption power and power ratio. Please refer to this analysis group:

This less accurate method means you will need to integrate the absorbed intensity. Since it needs integration in 3D, it is is less accurate than the built-in method to calculate RT directly. But it should give you fair result compared to your experiment as experiment measurement also has some kind of errors.