Calculation of photon and current fluctuations in traveling-wave semiconductor laser amplifiers

The noise properties of semiconductor laser amplifiers are calculated using the Heisenberg equations of motion. Photon noise as well as the recombination current noise are calculated with this formalism, and agreement with previously published results was found for the photon noise. The formalism also gave the conventional current shot noise in the appropriate limits, e.g., when using the amplifier reverse-biased as a detector. The method gives reasonable agreement with reported experimental results and the results for the current noise could be given a consistent physical explanation. Some concluding remarks concerning the relationship with the Langevin approach and the possibilities of minimizing the noise are given