Coherent instabilities in a semiconductor laser with fast gain recovery

We report the observation of a coherent multimode instability in quantum cascade lasers (QCLs), which is driven by the same fundamental mechanism of Rabi oscillations as the elusive Risken-Nummedal-Graham-Haken (RNGH) instability predicted 40 years ago for ring lasers. The threshold of the observed instability is significantly lower than in the original RNGH instability, which we attribute to saturable-absorption nonlinearity in the laser. Coherent effects, which cannot be reproduced by standard laser rate equations, can play therefore a key role in the multimode dynamics of QCLs, and in lasers with fast gain recovery in general.Comment: 5 pages, 4 figure

Superradiance from an ultrathin film of three-level V-type atoms: Interplay between splitting, quantum coherence and local-field effects

We carry out a theoretical study of the collective spontaneous emission (superradiance) from an ultrathin film comprised of three-level atoms with $V$-configuration of the operating transitions. As the thickness of the system is small compared to the emission wavelength inside the film, the local-field correction to the averaged Maxwell field is relevant. We show that the interplay between the low-frequency quantum coherence within the subspace of the upper doublet states and the local-field correction may drastically affect the branching ratio of the operating transitions. This effect may be used for controlling the emission process by varying the doublet splitting and the amount of low-frequency coherence.Comment: 15 pages, 5 figure

Problem of inversionless amplification

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Amplification without population inversion

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Lasers without population inversion

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Quantum electronics: maser amplifiers and oscillators

Quantum Electronics, Volume 2: Maser Amplifiers and Oscillators deals with the experimental and theoretical aspects of maser amplifiers and oscillators which are based on the principles of quantum electronics. It shows how the concepts and equations used in quantum electronics follow from the basic principles of theoretical physics.Comprised of three chapters, this volume begins with a discussion on the elements of the theory of quantum oscillators and amplifiers working in the microwave region, along with the practical achievements in this field. Attention is paid to two-level paramagnetic m

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. Copyright 1995 IEEESCOPUS: ar.jinfo:eu-repo/semantics/publishe

Quantum electronics: basic theory

Quantum Electronics, Volume 1: Basic Theory is a condensed and generalized description of the many research and rapid progress done on the subject. It is translated from the Russian language. The volume describes the basic theory of quantum electronics, and shows how the concepts and equations followed in quantum electronics arise from the basic principles of theoretical physics. The book then briefly discusses the interaction of an electromagnetic field with matter. The text also covers the quantum theory of relaxation process when a quantum system approaches an equilibrium state, and expla

Dynamics of a ring laser with diffusion of active centres

A dynamic theory of a bidirectional ring laser with a slow-response active medium is developed. This theory takes account of certain specific factors applicable to semiconductor and some solid-state active media, such as the diffusion of the light-emitting centres and nonisochro- nicity. These factors are shown to have a significant influence on the dynamic characteristics of a laser, because they change the conditions for a phase-sensitive interaction of counterpropagating waves in a population inversion grating induced by these waves. In particular, these factors give rise to a range where stable bidirectional lasing with equal wave intensities exists. They also complicate the dynamics of such a laser in the region of time-dependent processes. © 1995 Kvantovaya Elektronika and Turpion Ltd.SCOPUS: ar.jinfo:eu-repo/semantics/publishe