Steady state simulation. Modeling emission.

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.

SimphoSOFT running on tablets.

Can SimphoSOFT run on tablets?

SimphoSOFT can be installed on any tablet which is running one of the following flavors of Windows 8: Windows 8, Windows 8 Pro, or Windows 8 Enterprise. SimphoSOFT is NOT compatible with Windows 8 RT as it is not an App. The tablet should also have at least one standard size USB port to accommodate a security device Dongle.

Installing SimphoSOFT for all user accounts.

Can all the users of a host computer run SimphoSOFT from their accounts?

It is possible to allow all active users on the host computer to run SimphoSOFT from their accounts. For those who are interested, we can send a simple script which should be run from the user account with administrative rights, the one which was used to install SimphoSOFT. This script will create all necessary folders and shortcuts to successfully launch SimphoSOFT.

Post-simulation plots are not smooth.

My post-simulation plots are not smooth.

To get smoother plots along the time axis, insert a larger number than 32 in the post simulation 'Time Points' box.  The program calculated 512 time points (from # Iterations in 'Post Simulation'), so you can use numbers as large as 512 if you want.  This will not slow down the simulations.

Error 1086 during run.

 Is there any reason, this program is not running if I use post simulation time 10^9, it shows 1086 error but runs correctly at 10^7? Some of my decay at 10^7 are not complete, I am trying to do little longer time but not working.

The computer may be going into 'sleep' mode or 'hibernation' mode during the long runs.  That will cause the program to lose contact with the dongle and cause the program to stop with an error code.  Please turn off 'sleep' mode and 'hibernation' mode and let me know if that solves the problem.

What is workspace graph?

I am getting error: “All assigned components must be in the workspace graph”. What is workspace graph and why I am getting this error?                     

Workspace graph connects all the components along the beam path till it hits the target sample. For example, if a light beam goes through a beam splitter and a delayer before it reaches the target sample, all such components (beam, beam splitter, delayer and sample) will be connected in the workspace graph. These relationships are important for SimphoSOFT Math Kernel to recognize which setup component affect other components during simulation. The beam path is denoted by a dotted line: it starts from the beam component and ends at the sample component.

To start simulation the following rules should be satisfied:
        The beam path starts at a laser and ends at a sample or multi-layer sample
        All assigned components should be on the path of one of the laser beams
        Any assigned z-translations must have an associated assigned sample component

Project templates

Are project templates the only experimental setup configurations which SimphoSOFT can model?

No. Templates have been composed to help users to avoid repetitive steps in the process of creating an experimental setup.

Users can create an unlimited number of desired configurations in SimphoSOFT E-CAD by adding/moving new/existing components in the workspace. In addition, for an active material SimphoSOFT allows building energy level diagram of an arbitrary size and shape and defining desired transitions from a provided set of Simphotek Transition Modules. This enables users to model absorption, relaxation, energy transfer, upconversion, cross-relaxation (chemical reaction) between arbitrary levels (molecules) in the system.

Modeling reversible saturable absorber (RSA).

Can SimphoSOFT model a reversible saturable absorber?
Where can I define a saturation intensity parameter I0?

SimphoSOFT is capable of simulating reversible saturation absorption. However, it does not require a user to specify a value for saturation intensity I0 as the program takes care of saturable absorption automatically by explicitly modeling ground state depletion.

Introducing the saturation intensity I0 is a way to avoid solving rate equations to the full extent. It shows the intensity level at which the ground state will be depleted which will drastically reduce absorbing power of the active material. Up to some extent, one can just solve a propagation equation by using the intensity-dependent absorption rate A.

[CONVENTIONAL MODEL : with saturation intensity I0]

∂I  / ∂z = − A(I,z) I^2
A(I,z) =  α/(1+I/I0)

SimphoSOFT goes much further. It models depletion of the ground state explicitly by calculating the dynamics of population densities of all the energy levels. For example, if absorption from the ground state to the first excited state is strong and the relaxation is slow, the ground state will be depleted and the attenuation term in the propagation equation will be decreased substantially, which will stop absorption.


∂I(z,t)  / ∂z = − α N0(z,t) I(z,t)^2
∂N0(z,t)  / ∂t = − α N0(z,t) I(z,t)^2 /2 h ω0 – k10 (N-N0)

What is important is that a user provides a “intrinsic” value for the two-photon absorption cross-section.

To run this analysis in SimphoSOFT, one needs to define data snapshots in Run Configuration / Output tab. One should choose “Dyn popln dty” to output dynamics of population density at a desired sample depth and the distance from the beam center.

Dissipative medium

Does SimphoSOFT model dissipative medium?

SimphoSOFT allows defining linear absorption coefficient which can simulate dissipative medium. Absorption coefficient can be defined for each wavelength presented in the workspace.