Hi All,
Can anyone please let me know that what is the difference between a normal material (whose refractive index doesn't vary with wavelength e.g. Silica) and a Lorentz-Drude dispersive (whose refractive index varies with wavelength e.g. Ag, Au, Cu...). The difference needed is in terms of application to 2-D photonic crystal waveguides or in general how they will behave in front of light. My study is focused on the dispersion compensation by different materials applied to photonic defects.
There is no material whose refractive index does not vary. There are just regions in case of dielectrics where the variation is rather slow. The index changes are a connected to absorption. At very high frequencies the index starts with one and each absorption, starting from electronic absorptions over vibrational excitations in the middle infrared to rotation of permanent dipoles in the microwave add to the index of refraction. The difference in case of metals is, that they continuously change their refractive index below the plasma frequency, because the free electrons lead to absorption in the complete spectral region below this frequency. A good resource to understand this behavior is the Book of Bohren and Huffman, "absorption and scattering of small particles", chapter 10.
Thanks Dr. Thomas. My wavelength range of work is 400 - 1000 nm. Can I take the refractive index of Silica in this range as constant (~1.45) ?
At 400 nm the refractive index of Silica is about 1.47 (see link), so it is nearly constant in this range.
https://www.thorlabs.com/images/TabImages/UVFS_Index_of_Refraction_Graph_780.gif
As in the figure, the refractive index of Silica is varying from 1.47 to 1.45 in the wavelength range 0.4 - 1.0 um. Can I take the average of refractive index as 1.46 in that range. Also can you please provide the graph of variation of refractive index in the range 1.0 - 2.0 um ?
As in the figure, the refractive index of Silica is varying from 1.47 to 1.45 in the wavelength range 0.4 - 1.0 um. Can I take the average of refractive index as 1.46 in that range. Also can you please provide the graph of variation of refractive index in the range 1.0 - 2.0 um ?
As in the figure, the refractive index of Silica is varying from 1.47 to 1.45 in the wavelength range 0.4 - 1.0 um. Can I take the average of refractive index as 1.46 in that range. Also can you please provide the graph of variation of refractive index in the range 1.0 - 2.0 um ?
At least you can try to take the average value.
https://www.rp-photonics.com/img/silica_index.png
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