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Photonics

Photonics

Topics related to Lumerical and more.

Absorption of materials in infrared regions

    • Term
      Subscriber

      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
      Ansys Employee

      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.

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