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The bandwidth properties of chaotic signals generated by semiconductor lasers subject to strong chaotic optical injection (COI) are investigated numerically. The chaotic output of an injection master laser (ML) is injected into the slave laser (SL). The effects of feedback strength, injection strength and bias current on the bandwidth properties are discussed in detail. Some novel results are found, the bandwidth for SL increases with the injection strength firstly until reaches a maximum, and then decrease to approach the bandwidth of ML due to the injection-locking chaos synchronization. Large feedback strength and bias current contributes to higher maximum chaotic bandwidth in the range of injection strength. That is to say, for given parameters, optimal injection strength exists contributing to highest chaotic bandwidth, and moves to a large value for a large feedback strength and bias current, which is extremely useful for increasing the transmission rate of the optical chaotic communication system. [ABSTRACT FROM AUTHOR]

Transient characteristics of SiGe-QW laser structures were studied. The excitation of stimulated THz emission is shown to be the result of carrier injection through contacts. The mechanism of intra-center population inversion caused by carrier injection is suggested. [ABSTRACT FROM AUTHOR]

The specific features of the behavior of electron states in GaAs/AlGaAs double quantum well structure with strongly asymmetric barriers in an external electric field have been studied both theoretically and experimentally. This structure is the principal part of the active element of a quantum unipolar laser proposed by us earlier, since it contains the lower laser subband possessing the property of 2D–3D transformation. The drastic variations in the photoluminescence peak intensity, FWHM, and area with field demonstrate the possibility of controlling the dimensionality of this subband. [ABSTRACT FROM AUTHOR]