Gennady A. Koganov

Dressed-state analysis of lasing without population inversion in a three-level ladder system: the temporal regime

We present a time-dependent study of a three-level ladder scheme interacting with two electromagnetic fields, utilizing a dressed-state approach. Analytical expressions for time-dependent populations and coherences are obtained under the secular approximation. These are found in good agreement with exact numerical solutions. It is found that the system exhibits gain both with and without inversion. The calculated temporal gain is found to be essentially larger than the steady-state gain. The frequency response of density matrix elements has been studied. Both normal and abnormal dispersion?absorption relations have been obtained.

Field-driven super/subradiant lasing without inversion in three-level ladder scheme

A model of a superradiant laser comprising of N three-level systems driven by two pumping lasers is considered in semiclassical approximation. Steady-state equations for density matrix elements are solved both analytically and numerically. Various properties of generated light are investigated. It is found that such a laser can exhibit both superradiance, when the intensity scales as N(2), and subradiance when the intensity does not depend on N. The phase of the laser field is locked to the relative phase of the pumping lasers.

Multimirror autodyne lidar for local detection of hostile gases.

We describe an autodyne lidar with multiple external mirrors by using an analytical approach presented previously [Appl. Opt. 41, 7087 (2002)]. The use of multiple target mirrors allows one to detect and locate the concentration of species between any pair of neighboring mirrors.

THRESHOLD AND NONLINEAR BEHAVIOR OF LASERS OF LAMBDA AND V CONFIGURATIONS

Dynamic properties of closed three-level laser systems are investigated. Two schemes of pumping\char22{}

Super/subradiant frequency doubling by quantum wells coupled to external resonator

\ensuremath{\Lambda}

Analytical estimation of the parameters of autodyne lidar

and V\char22{}are considered. It is shown that the nonlinear behavior of the photon number as a function of pump both near and far above threshold is crucially different for these two configurations. In particular, it is found that in the high pump regime laser can turn off in a phase-transition-like manner in both

Quantum resonances by sequential pulsed excitation with pulse repetition rate at fractional atomic frequencies

\ensuremath{\Lambda}

Coherent control of ac-Stark allowed transitions

and V schemes.

Nonlinear behavior of lasers with different schemes of pumping

A scheme for active frequency doubling is suggested. The system comprises N semiconductor quantum wells situated into resonant cavity. Theoretical model for such systems is based on three-level virtual atoms in ladder configuration. It is found that the system can lase in either superradiant or subradiant regime, depending on the number of atoms N. When N passes some critical value the transition from the super to subradiance occurs in a phase-transition-like manner. Stability study of the steady state supports this conclusion.

Quantum correlation of recycling times in regularly pumped laser

An analytical approach for a calculation of the parameters of autodyne lidar is presented. Approximate expressions connecting the absorption coefficient and the distance to the remote target with both the lidar parameters and the measured quantities are obtained. These expressions allow one to retrieve easily the information about the atmosphere from the experimental data.