Abstract

The transient evolution of the output of a single-mode laser diode (SMLD) after it is switched on has usually been characterized by the evolution of the output intensity,^[1] but the evolution of its spectral characteristics is of major importance in communication systems.^[2] We model the SMLD by noise driven rate equations. The inclusion of wide-band noise in the evolution equations prevents to identify $\dot{\phi }$ with the field frequency experimentally observed, f_i. Experimental measurements of the laser frequency are based on time resolved spectra of the electric field.^[3] Their realtion to the stochastic equation for the evolution of the phase has been discussed in,^[4] showing that the frequency during the optical pulse is independent of phase noise, but with fluctuations due to random initial conditions at the beginning of the pulse. The reason is that the random turn-on time t^* - defined as when the intensity reaches for the first time a value I_r - determines the beginning of a deterministic stage of evoulution, and the initial condition for this period.^[4]

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