We have measured the evolution of the intensity emitted by a randomlaser during a pump pulse that is comparable in duration to thespontaneous emission decay time. The time traces of our random laser,consisting of titanium dioxide particles and sulforhodamine B dye, showclear relaxation oscillations. We compare our experimental results to ananalytic, conventional model based on the four-level rate equations fora single-mode laser. The measured frequency of well-resolved fluctuationoscillations suggests an effective mode lifetime of 5 ps.

K.L. van der Molen, A. P. Mosk, A. Lagendijk

2009

11/2009

Phys. Rev. A

80

055803

1-4

random lasers, relaxation oscillations