SPECTROSCOPY OF SUPERMODES IN AN SPML LASER

The spectral composition of the radiation of a pulse laser with a shor t-time periodic modulation of losses (SPML) in an active medium with a homogeneously broadened line is analyzed using the one-dimensional Sc hrodinger equation. It is shown that oscillations of the normal type i n this laser are periodic wave formations, the suggested name of which is ''supermodes.'' Their use made it possible to put forward for the first time a theoretical model for describing oscillation in an SPML l aser. A numerical model of an SPML laser, which was developed earlier and was supported by physical experiments, provided the basis for a nu merical experiment. This experiment showed that the radiation of an SP ML laser definitely consists of supermodes and that several supermodes can simultaneously take part in oscillation. However, when the resona nce modulation of losses is sufficiently long, the regime of oscillati on of the zeroth-order supermode usually sets in. Numerical studies at the nonlinear stage of oscillation revealed that lower supermodes are selected at this stage. When a supermode with an order higher than ze ro is generated, its profile is modified because of the transfer of th e pulse energy into the first maxima of this supermode. Problems of th e spectroscopy of supermodes in an SPML laser are discussed. It is sho wn that the effect of periodic modulation of the integral spectrum of an SPML laser, detected earlier, can be used for this spectroscopy. To prove this, an experiment on a ruby SPML laser was staged. The result s of this experiment verify the results of the numerical experiment.