相关论文: Intersubband gain in a Bloch oscillator and Quantu…

A density matrix theory of electron transport and optical gain in quantum cascade lasers in an external magnetic field is formulated. Starting from the general quantum kinetic treatment, we describe the intra- and inter-period electron…

Gain in current-driven semiconductor heterostructure devices is calculated within the theory of nonequilibrium Green functions. In order to treat the nonequilibrium distribution self-consistently the full two-time structure of the theory is…

Time-resolved spectroscopy-based pump-probe experiments performed on quantum cascade lasers (QCLs) exhibit an initial fast gain recovery followed by a slow tail such that the equilibrium gain is not recovered in a cavity round-trip time.…

We show that mid infrared transmission spectroscopy of a quantum cascade laser provides clear cut information on changes in charge location at different bias. Theoretical simulations of the evolution of the gain/absorption spectrum for the…

Quantum cascade lasers can be modeled within a hierarchy of different approaches: Standard rate equations for the electron densities in the levels, semiclassical Boltzmann equation for the microscopic distribution functions, and quantum…

We develop a quantum model for the calculation of the gain of phonon-polariton intersubband lasers. The polaritonic gain arizes from the interaction between the electrons confined in a quantum well structure and the phonon confined in one…

Intersubband transitions in a superlattice under homogeneous electric field is studied within the tight-binding approximation. Since the levels are equi-populated, the non-zero response appears beyond the Born approximation. Calculations…

We theoretically analyze the influence of magnetic field on small-signal absorption and gain in a superlattice. We predict a very large and tunable THz gain due to nonlinear cyclotron oscillations in crossed electric and magnetic fields. In…

We study theoretically the performance of electrically pumped self-organized quantum dots as a gain material in the mid-IR range at room temperature. We analyze an AlGaAs/InGaAs based structure composed of dots-in-a-well sandwiched between…

The transport of Bloch electrons under strong fields is traditionally understood through two mechanisms: intraband Bloch oscillations and interband Zener tunneling. Here, we propose an oscillation mechanism induced by the interband quantum…

We present a quantum theoretical analysis of the electroluminescence from an intersubband transition of a quantum well structure embedded in a planar microcavity. By using a cluster factorization method, we have derived a closed set of…

Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed…

Multiphoton excitation of a solid by a few-cycle, intense laser pulse forms a very non-equilibrium distribution of charge carriers, where occupation probabilities do not necessarily decrease with energy. We show that, under certain…

Silicon-based terahertz quantum cascade lasers (QCLs) offer potential advantages over existing III-V devices. Although coherent electron transport effects are known to be important in QCLs, they have never been considered in Si-based device…

The linewidth in intersubband transitions can be significantly reduced below the sum of the lifetime broadening for the involved states, if the scattering environment is similar for both states. This is studied within a nonequilibrium Green…

By combining band gap engineering with the self-organized growth of quantum dots, we present a scheme of adjusting the mid-infrared absorption properties to desired energy transitions in quantum dot based photodetectors. Embedding the self…

We theoretically consider the amplification of THz radiation in a superlattice Bloch oscillator. The main dilemma in the realization of THz Bloch oscillator is finding operational conditions which allow simultaneously to achieve gain at THz…

We report gain calculations for a quantum cascade laser using a fully self-consistent quantum mechanical approach based on the theory of nonequilibrium Green functions. Both the absolute value of the gain as well as the spectral position at…

A many-body theory based on nonequilibrium Green functions, in which transport and optics are treated on a microscopic quantum mechanical basis, is used to compute gain and absorption in the optical and THz regimes in quantum cascade laser…

We report the experimental realization of a new kind of optical lattice for ultra-cold atoms where arbitrarily large separation between the sites can be achieved without renouncing to the stability of ordinary lattices. Two collinear…