A. I. Odintsov

New methods of control of fast-flow laser operation regimes

Fast-flow lasers with controllable dynamical regimes were analyzed. Generator-amplifier resonator system considered in the paper was found to possess particular physical mechanism of self-modulated pulsing. The mechanisms lie in the generator and amplifier interaction due to the feedback supplied with the flow. One of the mechanisms is the inversion saturation in the amplifier, which determines the gain of the medium entering the generator. At the same time spatial modulation of the gain profile, as a result of the edge effects in non-stationary optical field, can also affect the regime of lasing. Methods of a regime control based on mechanisms mentioned above are proposed.

The stability of the stationary generation of a multichannel laser

Stable generation of multi-channel lasers that find application in optical communication systems with spectral multiplexing is studied theoretically. A computational model to determine the frequencies and increments of self-oscillating perturbations depending on the key laser parameters and the characteristics of the channels cross-saturation is proposed. It is shown that for typical conditions of an erbium-doped fiber laser, multichannel generation with a large number of channels (more than ten), although stable, is characterized by large fluctuations of channel power due to the very small decay increments of perturbations caused by small technical fluctuations of the laser parameters.

Free-running instability in laser systems when the active medium moves in a spatially periodic field

Using a flow-through laser with an unstable-cavity-multibeam-amplifier optical system as an example, it is shown that, when the active medium moves through a spatially periodic field, self-excited perturbations can build up in the flow of the medium, resulting in instability of the steady-state lasing. This phenomenon is explained by the interference of the perturbation waves formed in the moving medium at the edges of the beams.

Self-pulsing instabilities in fast-flow gas lasers

Perturbation exchange processes in two-component active medium such as CO2 : N2 gas mixture were shown to be a significant factor determined the threshold of self-pulsing oscillations in FFL. Analytical expressions allowed to define increments and frequencies of the oscillations on the base of stationary lasing parameters were obtained

Relaxation oscillations of power in an unstable resonator of fast-flow laser

Numerical simulation indicates that the mechanism of self-pulsing instabilities in fast-flow laser with unstable resonator is connected in many cases with teh rise of relaxation oscillations. Spatial structures, frequencies and increments of the perturbation modes have been calculated in linear approximation. Effects of interaction of relaxation oscillations and flow self-oscillations such as pulling and locking of frequencies were observed. The transformation of relaxation self-oscillations into different saturated regimes of lasing was also investigated. The regimes may be of practical interest due to high pulse repitition rate (up to 104 Hz).

Relaxation pulsing regime of fast-flow laser with unstable resonator

New regime of self-pulsing generation in the unstable resonator (UR) of the transverse flow laser was found numerically. The regime is characterized with high pulse repetition rate (Omega) Rapproximately equals 102/(tau) f ((tau) f is the time required for the medium to flow from the edge to the axis of the resonator). It can be considered as relaxation pulsing regime and can be interesting from the point of view of material laser treatment technology. Various regimes of lasing can be easily commuted over.