Ya I Khanin

Influence of carrier diffusion on the dynamics of a two-mode laser

The two-mode semiconductor laser rate equations are generalized to account for the diffusion of free carriers. Using the diffusion coefficient as a control parameter we analyze the competition between small-scale and large-scale gratings in the laser dynamics. Many solutions become unstable as the diffusion coefficient decreases. >

Bifurcations and chaos in the three-level model of a laser with coherent optical pumping

Abstract A three-level laser model, taking into account coherent interaction of pump and generated field, is discussed. Possible simplifications of this model are discussed for some particular cases. The characteristic features of a general model and its simplified version, a Lorentz model, are investigated using computation methods. The obtained results are compared with the known data of experimental investigations of optically pumped molecular lasers.

Chaos in a solid-state laser with periodically modulated losses

Abstract It is shown theoretically that an experimentally observable chaotic behavior may arise in a single-mode solid-state laser when its losses are periodically modulated with a frequency less than half the frequency of the relaxation oscillations.

Experimental study of spectral condensation of dye laser emission near the absorption lines of intracavity atoms

Abstract Experimental data prove the nonlinear nature of the phenomenon under study. It is assumed that the mechanism of spectral condensation is related to the Kerr nonlinearity of the absorbing gas rather to the phase grating induced by the intracavity standing waves (saturation effect).

Low frequency relaxation oscillations in class B lasers with feedback

Relaxation oscillations have been studied both theoretically and experimentally in a multimode YAG laser in the presence of a derivative feedback. In addition to the standard relaxation oscillations, discrete low frequency components are present in the noise spectrum of each individual mode but they compensate almost exactly in the total intensity. The influence of a combined derivative feedback involving both the total intensity and that of one selected mode on the behavior of the relaxation oscillations and nonlinear dynamics of the laser is investigated. It is shown that the compensation nature of the low frequency relaxation oscillations of the multimode class B lasers can be disturbed in this case and, as a consequence, the selected relaxation oscillations appear in the noise spectrum of the total intensity. A higher feedback level can induce a destabilization of the laser and eventually chaos. An excellent qualitative agreement between experiments and theory has been obtained.

Disappearance of relaxation oscillation frequencies in a multimode solid-state laser

Abstract We study analytically the Tang, Statz and deMars rate equations describing a solid-state Fabry-Perot laser. When the modes have equal gains, there is a critical number of lasing modes, above which the low-frequency relaxation oscillations responsible for antiphase dynamics disappear. These results are generalized to include unequal modal gains resulting from a Lorentzian gain profile.

Low-frequency dynamics of lasers.

An approach to nonlinear dynamics of multimode lasers is developed. It is based on the concept of two systems of eigenoscillations: optical modes and relaxation oscillations. The importance of a correct (not arbitrary) choice of a model is underlined. Characteristic features of two different rate equation models are formulated and compared. A method of selective perturbation on the system is described which makes it possible to study interrelations between optical modes and relaxation oscillations, and to control dynamical behavior of a laser. The possibility of using dynamical regularities for solving both applied and basic problems is illustrated in several examples. (c) 1996 American Institute of Physics.

Polarization dynamics of a fibre Fabry-Perot laser with feedback

Experimental results on the low-frequency polarization dynamics of a free-running Nd-doped optical fibre laser and a fibre laser with derivative feedback are presented. It is found that the power spectrum of each polarization mode reveals three relaxation peaks. Using the combined (negative and positive) derivative feedback it is possible to suppress noise in the region of the in-phase relaxation oscillations and to excite noise in the region of one of the two antiphase relaxation oscillations. The model developed of a class B laser with two orthogonal elliptically polarized modes is checked and explains the main experimental features of relaxation oscillation peaks.

Sweep-laser on dynamic modes

Abstract A new method of laser frequency tuning consisting in tuning of the selective cavity with a simultaneous change of its length is reported. The operating conditions are briefly analyzed and experimental results are discussed. The continuous tuning range obtained for Nd:glass sweep-laser is ∼ 100 cm -1 .

Multimode fabry-perot laser: Number of relaxation frequencies

We study analytically the Tang, Statz, and deMars equations describing a solid-state Fabry-Perot laser to determine how many relaxation oscillations it displays. When the modes have equal gains, the number of relaxation oscillations varies between zero and the mode number, depending on the laser parameters. In particular, a large number of modes or a relatively large pumping rate leads to the elimination of all relaxation oscillations except one, thereby simplifying the noise spectrum. These results are generalized to include unequal modal gains such as might result from the Lorentzian gain profile.