Random lasers don't have cavities. The feedback in random lasers is provided by scattering in a gain medium. The efficiency of the feedback is described in terms of a photon residence time in a scattering medium. The dynamics of the random laser emission is determined by the pumping energy density, the shape and the duration of the pumping pulse (in this model, we assume a gaussian pulse-shape), the emission cross section of the gain medium, and the experimental decay time. The effective absorption length at the pumping pulse duration is determined by the combination of absorption and scattering processes.
The experimental decay time includes both radiated and non-radiated process. The model assumes that the random laser medium is semi-infinite and that it does not have any absorption at the emission wavelength.
This program demonstrates how the stimulated emission dynamics, which often can produce several short stimulated emission pulses in response to a longer pumping pulse, depends on the parameters above. The principles of operation of random lasers can be found in online presentation by Mikhail A. Noginov (Random Lasers - http://nanohub.org/resources/1311) or in the book "ISBN: 978-0-387-23913-2 - M. A. Noginov, Solid-State Random Lasers, Springer, 2005".
The limits for the parameter are set in a such way that the program operates in a stable regime for the most combinations of values corresponding to the most common experimental situations. Some exotic combinations of parameters can cause the Rappture to crush. In this case, return to the sets of the parameters, which are closer to the default values.
M. A. Noginov, Solid-State Random Lasers, Springer, 2005
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