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fdtd:broadband

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Broadband calculations in FDTD are based on use of a broadband excitation, so instead of feeding our source with a sine function we use something with wider spectrum, like Gaussian function. Then we analyze the results using Fourier transform to get the spectral dependence. | Broadband calculations in FDTD are based on use of a broadband excitation, so instead of feeding our source with a sine function we use something with wider spectrum, like Gaussian function. Then we analyze the results using Fourier transform to get the spectral dependence. | ||

- | An example that can be used to benchmark such calculation can be the reflection on a thick gold metal layer, that should give the results comparable to literature values. | + | An example that can be used to benchmark such calculation can be the reflection on a thick gold metal layer, that should give the results comparable to reference values ([[http://refractiveindex.info|refractiveindex.info]]). |

{{ :samples:broadband.png?500 |}} | {{ :samples:broadband.png?500 |}} | ||

+ | Note that the disagreement between the model results and reference values is mostly caused by the Drude+2CP model itself - the dielectric properties used in the calculations are already an approximation. | ||

There are several aspects to consider when setting up broadband calculations. The FFT result is discrete and the set of wavelengths that are computed depends on the length of the input data. As seen above, it is also non-linear, the most dense are the high frequencies (short wavelengths). The source itself has some spectral dependence and the result should be corrected for this (the source spectrum is automatically placed in xspectrum.txt file). | There are several aspects to consider when setting up broadband calculations. The FFT result is discrete and the set of wavelengths that are computed depends on the length of the input data. As seen above, it is also non-linear, the most dense are the high frequencies (short wavelengths). The source itself has some spectral dependence and the result should be corrected for this (the source spectrum is automatically placed in xspectrum.txt file). |

fdtd/broadband.txt ยท Last modified: 2018/09/25 10:29 by pklapetek

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