Is there any way to do a steady state simulation in this software?
If I want to see the real population of the each level, I would be able to predict the emission intensity.
The possibilities for predicting the amount of emitted light depend on whether 1) you are using a CW laser and looking at steady state emission or 2) you are using a pulsed laser and are looking for the number of emitted photons from a single pulse.
1) For steady state simulations:
Use the 'box' shaped pulse that has a flat top. For the pulse width (FWHM), pick a pulse width that is longer than the longest relaxation time for the ion. This will allow the ions to come to approximately a steady state near the end of the pulse. Note that for a 'box' pulse, the internal program variable T0 will be 1/2 of the pulse width FWHM. In Numerical Setup, you may pick the 'Temporal Domain' as 2 times T0 (instead of 5) . Also note that the center of the pulse is at 0, so the temporal domain of 2*T0 actually goes from -T0 to +T0. After doing a simulation, compare the energy level populations near the end of the pulse.
2) For a single short laser pulse:
Look at the time dependence of the population of the emitting state by running the program with Post-Simulation. Pick a post-simulation time long enough to see the full decay. In Plot Creator, generate a 2D plot of the kinetics of the population density at the center of the pulse (rho = 0). Select the resulting plot with the mouse, right click on the plot and then select the option 'Integral'. Using 'Integral', you may integrate the area under the curve of population versus time. The area is proportional to the number of electrons that relax from that state. If there is more than one relaxation pathway from that state, you will need to multiple the area under the curve by a factor equal to (rate of emission from the energy level)/(sum of all rates from the energy level) to get the fraction of electrons that emit photons.