We present a detailed experimental study of photoluminescence upconversion in GaAs quantum wells over a wide temperature range. The dependence of the upconversion on the well width is discussed and the conversion efficiency is determined as a function of laser detuning. The best results are achieved when the laser detuning is comparable to the thermal energy of the system, ∆E ≈ 2kBT .

The interaction of a trapped ion with a laser beam in the strong excitation regime is analyzed. In this regime, a variety of non{classical states of motion can be prepared either by using laser pulses of well de ned area, or by an adiabatic passage scheme based on the variation of the laser frequency. We show how these states can be used to investigate fundamental properties of quantum mechanic...

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 threshold are in excellent agreement with experimental findings for T = 77K. The gain strongly decreases with temperature.

By analyzing the interaction of a few-cycle laser pulse within an asymmetric semiconductor double quantum well structure, we show that the transient coherence thus produced is strongly dependent on the carrier-envelope-phase (CEP) and significantly enhanced due to the Fano-type interference. A method to determine the CEP is proposed by directly mapping the CEP dependent coherence to the quantum...

In the past 20 years the semiconductor laser has become a key device in optical electronics because of its pure output spectrum and high quantum efficiency. As the capabilities of laser diodes have grown, so has the range of applications contemplated for them. The laser performance successes gained using quantum wells in optoelectronic devices can be extended by adopting quantum dot structures....

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Spin exchange between a single-electron charged quantum dot and itinerant electrons leads to an emergence of Kondo correlations. When the quantum dot is driven resonantly by weak laser light, the resulting emission spectrum allows for a direct probe of these correlations. In the opposite limit of vanishing exchange interaction and strong laser drive, the quantum dot exhibits coherent oscillatio...

In addition to spaceand time-resolved measurements of the electrical generation of excited electrons in quantum Hall (QH) devices the dissipation in these devices induced by Terahertz (THz) laser impulses is investigated. For these tasks a THz laser system ( p-Ge-Laser [1]) is applied. This laser uses transitions between Landau levels of light holes and emits laser impulses with an adjustable d...

In laser structures where the active region consists of several quantum wells, non-uniform charge injection can occur. We examine the consequences of non-uniform charge injection on gain, threshold current, and linewidth enhancement factor. Non-uniform charge injection in a InP-based multiple quantum well laser was considered in order to analyze effects on gain, threshold current, and linewidth...

This paper represents the study of light sources for optical communication through the optical fiber. For this purpose, the ideal light source characteristics have been studied. According to the study, the semiconductor LASER diodes are preferable sources over LEDs. From the family of LASER diodes, Distributed Feedback (DFB) lasers are considered as source. They have low threshold current and h...