Notice that the fields do not decay significantly by the end of the simulation. Line 1 (blue) is the complete time signal and Line 2 (green) shows the portion of the time signal that will be used in the analysis. The following figures show the time signal from a high Q cavity. The required time is problem dependent, but typically 1-2 times the source pulse is sufficient. Similar to Low Q cavities, it is necessary to disregard the initial portion of the time signal due to transients from the initial source pulse. Script command to extract the Q from a portion of the time signal. The Q-factor is then calculated via \(Q=\frac\). Calculating the R and T around this line with higher resolution shows a Lorentzian line-shape with a peak wavelength at around \(\lambda_0 = 988.44nm \).īy using the “findpeaks” script command, the center frequency \(f_0 \) can be determined automatically and more accurately. In the corresponding plot, we can identify a sharp line in the middle of the band gap. The script then calculates and plots the reflectivity and transmissivity of the entire cavity structure with both mirrors. This region is also referred to as the band gap. For this example, we find almost perfect reflection in the wavelength range from 800nm-1200nm. To do so, it uses the script command “stackrt” to analytically calculate the reflectivity and transmissivity of a single Bragg mirror. The script will first obtain the analytical reference solution. It will run the simulation and do all associated analysis.Īnalytical calculation of reflectivity and transmissivity Open the simulation file and corresponding script file.
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