The generation mechanism of self-sustained pulsation in vertical-cavity surface-emitting lasers (VCSEL’s) is analyzed with the influence of lateral loss effects, such as selffocusing, lateral diffraction loss, and spatial hole burning, taken into consideration. The condition for self-sustained pulsation is also derived in an analytical form. It is shown that the lateral loss effects have signif...

We use a new rate-equation model for the propagation of sub-picosecond polarized optical pulses in a semiconductor optical amplifier (SOA). This model is based on the decomposition of the polarized optical field into TE and TM components that interact via the gain saturation, and accounts for two-photon absorption, free-carrier absorption, selfand cross-phase modulation, carrier heating, and sp...

Measured gain compression, differential gain, and damping of strained quantum wire lasers are reported and related to attributes specifically traceable to carrier confinement in two dimensions. A comparison is made with the properties of ridge lasers grown simultaneously. Damping and K factors are found to be comparable in the two structures. The differential gain is found to increase by two or...

The generation of frequency combs in the mid-infrared and terahertz regimes from compact and potentially cheap sources could have a strong impact on spectroscopy, as many molecules have their rotovibrational bands in this spectral range. Thus, quantum cascade lasers (QCLs) are the perfect candidates for comb generation in these portions of the electromagnetic spectrum. Here we present a theoret...

In this study, we report the unequivocal demonstration of midinfrared mode-locked pulses from quantum cascade lasers. The train of short pulses was generated by actively modulating the current and hence the gain of an edge-emitting quantum cascade laser (QCL). Pulses with duration of about 3 ps at full-width-at-half-maxima and energy of 0.5 pJ were characterized using a second-order interferome...

Work to date on self-induced transparency modelocking in quantum cascade lasers QCLs has neglected backward-propagating waves and lumped mirror losses. In this work, we remove these unrealistic assumptions. The qualitative features of the modelocking are unaffected by this improvement in the model, but the parameter regime in which stable modelocked pulses may be found is reduced. This reductio...

Calculations are reported of the eeect of birefringence on the selection of polarization states for the case of a weakly index guided Vertical-Cavity Surface Emitting Laser supporting both a fundamental and a higher-order transverse mode. The innuence of the refraction index step of the waveguide on the polarization behaviour of the laser is elucidated. It is found that for large refraction ind...

Weakly scattering random lasers exhibit lasing modes that spatially overlap and can interact strongly via gain saturation. Consequently, lasing in highthreshold modes may be suppressed by strong low-threshold lasing modes. We numerically examine the effect of inherent spontaneous emission noise on this strong nonlinear phenomenon. With a method to incorporate this noise into the Maxwell–Bloch e...

Since there is an increasing demand for fast networks and switches, the electronic data processing imposes a severe bottleneck and all-optical processing techniques will be required in the future. All-optical flip-flops are one of the key components because they can act as temporary memory elements. Several designs have already been demonstrated but they are often relatively slow or complex to ...

Surface-emitting lasers with an external cavity delivering a diffraction-limited beam have shown the potential to outperform edge-emitting devices in applications demanding high brightness (emitted intensity per unit solid angle), like pumping of doped fiber amplifiers or frequency doubling [1]–[3]. Due to the large mode size, the VECSEL concept is powerscalable by expanding the pumped area and...