Reduced auger recombination in mid-infrared semiconductor lasers

A quantum-design approach to reduce the Auger losses in two micron InGaSb type-I quantum well edge-emitting lasers is reported. Experimentally realized structures show a 3X reduction in the threshold, which results in 4.6 lower Auger current loss at room temperature. This is equivalent to a carrier lifetime improvement of 5.7 and represents about a 19-fold reduction in the equivalent “Auger coefficient.

Coulomb enhancement of high harmonic generation in monolayer transition-metal dichalcogenides

High harmonic generation (HHG) in monolayer MoS$_2$ is studied using fully microscopic many-body models based on the semiconductor Dirac-Bloch equations and density functional theory. It is shown that Coulomb correlations lead to a dramatic enhancement of HHG. Especially near the bandgap enhancements of two orders of magnitude or more are observed for a wide range of excitation wavelengths and intensities. For excitation near or above the excitonic resonances the Coulomb interaction leads to spectrally broad sub-floors of the harmonics. The widths of these contributions depends strongly on the dephasing time for polarizations. For times on the order of ten femtoseconds the broadenings are similar to the Rabi energies and reach one eV at fields of about 50 MV/cm. The intensities of these contributions are about four to six orders below the peaks of the harmonics

Propagation Induced Dephasing in Semiconductor High-Harmonic Generation

The influence of propagation on the nonperturbative high-harmonic features in long-wavelength strong pulse excited semiconductors is studied using a fully microscopic approach. For sample lengths exceeding the wavelength of the exciting light, it is shown that the propagation effectively acts as a very strong additional dephasing that reduces the relative height of the emission plateau up to six orders of magnitude. This propagation induced dephasing clarifies the need to use extremely short polarization decay times for the quantitative analysis of experimental observations.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

High power sub-200fs pulse generation from a colliding pulse modelocked VECSEL

We present a passive and robust mode-locking scheme for a Vertical External Cavity Surface Emitting Laser (VECSEL). We placed the semiconductor gain medium and the semiconductor saturable absorber mirror (SESAM) strategically in a ring cavity to provide a stable colliding pulse operation. With this cavity geometry, the two counter propagating pulses synchronize on the SESAM to saturate the absorber together. This minimizes the energy lost and creates a transient carrier grating due to the interference of the two beams. The interaction of the two counter-propagating pulses in the SESAM is shown to extend the range of the modelocking regime and to enable higher output power when compared to the conventional VECSEL cavity geometry. In this configuration, we demonstrate a pulse duration of 195fs with an average power of 225mW per output beam at a repetition rate of 2.2GHz, giving a peak power of 460W per beam. The remarkable robustness of the modelocking regime is discussed and a rigorous pulse characterization is presented.Air Force Office of Scientific Research [FA9550-14-1-0062]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]