Showing papers by "Nikolai N. Ledentsov published in 2005"
TL;DR: In this paper, a two-section quantum-dot laser that produces output powers up to 45 mW at 1260 nm was demonstrated. The pulse duration could be varied from 2 ps to as short as 400 fs at the 21 GHz pulse repetition rate.
Abstract: We demonstrate mode locking in a two-section quantum-dot laser that produces output powers up to 45 mW at 1260 nm. The pulse duration could be varied from 2 ps to as short as 400 fs at the 21 GHz pulse repetition rate.
157 citations
TL;DR: In this paper, the defect reduction technique (DRT) applied to thick layers enables realization of defect-free structures on top of dislocated templates, achieving low-threshold injection lasing up to 1350 nm wavelength at 300K using InAs-GaAs QDs.
Abstract: Quantum dot (QDs) heterostructures structurally represent tiny 3D insertions of a narrow bandgap material, coherently embedded in a wide-bandgap single-crystalline matrix. The QDs are produced by conventional epitaxial techniques applying self-organized growth and behave electronically as artificial atoms. Strain-induced attraction of QDs in different rows enables vertically-coupled structures for polarization, lifetime and wavelength control. Overgrowth with ternary or quaternary alloy materials allows controllable increase in the QD volume via the island-activated alloy phase separation. Repulsive forces during overgrowth of QDs by a matrix material enable selective capping of coherent QDs, keeping the defect regions uncapped for their subsequent selective evaporation. Low-threshold injection lasing is achieved up to 1350 nm wavelength at 300K using InAs-GaAs QDs. 8 mW VCSELs at 1.3 μm with doped DBRs are realized. Edge-emitters demonstrate 10 GHz bandwidth up to 70°C without current adjustment. VCSELs show ~4 GHz relaxation oscillation frequency. QD lasers demonstrate above 3000 h of CW operation at 1.5 W at 45°C heat sink temperature without degradation. The defect reduction technique (DRT) applied to thick layers enables realization of defect-free structures on top of dislocated templates. Using of DRT metamorphic buffer layers allowed 7W GaAs-based QD lasers at 1500 nm.
20 citations
TL;DR: In this paper, a waveguide designed as a one-dimensional photonic band crystal with an irregularity (defect) to achieve low-divergence emission was presented.
Abstract: We report on the lasers with a waveguide designed as a one-dimensional photonic band crystal with an irregularity (defect) to achieve low-divergence emission. Small vertical divergence less than 10o, high differential efficiency of 85% and CW output power of 1.8 W (10.6 W pulsed) have been obtained. For lasers with increased modal spot size very small vertical divergence emitting angle of 4.8o has been realized. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
16 citations
TL;DR: In this article, the effects of local heating of the samples with laser radiation during measurements of the Raman signals, photoresist hardening resulting from the oxidation, and overoxidation are analyzed.
Abstract: Raman scattering spectroscopy is used to study the process of selective oxidation of Al0.97Ga0.03As layers. Stresses arising in GaAs/(AlGa)xOy layers as a result of selective oxidation under different conditions are determined. The effects of local heating of the samples with laser radiation during measurements of the Raman signals, photoresist hardening resulting from the oxidation, and overoxidation are analyzed. The instrumentation and method of selective oxidation are optimized; as a result, arrays of vertical-cavity surface-emitting lasers are fabricated. The active region of these lasers is based on two InGaAs quantum wells with top oxidized and bottom semiconductor distributed Bragg reflectors.
12 citations
TL;DR: In this paper, a process of fabricating microcavities and photon crystals in GaAs structures by means of electron lithography and reactive ion etching is described, and two types of structures, with micropillars and with photon crystals, are considered.
Abstract: A process of fabricating microcavities and photon crystals in GaAs structures by means of electron lithography and reactive ion etching is described. Two types of structures, with micropillars and with photon crystals, are considered. The latter structures have the form of a square or hexagonal array of holes in a planar waveguiding structure. The minimal diameter of the micropillars is 100 nm, and their height is 700 nm. The size of the holes in the photon crystals and the photon crystal period are controllably varied from 140 to 500 nm and from 400 to 1000 nm, respectively. The etch depth of the crystals is more than 350 nm.
1 citations
TL;DR: In this paper, it is assumed that the observed effect is associated with the structural anisotropy, i.e., with the formation of an array of GaAs quantum wires.
Abstract: Dichroism in the transmission of light (the dependence of the transmittance on the direction of polarization of light) is revealed in corrugated GaAs/AlAs superlattices grown on a nanofaceted A(311) surface. It is assumed that the observed effect is associated with the structural anisotropy, i.e., with the formation of an array of GaAs quantum wires. This inference is confirmed by high-resolution electron microscopy. The GaAs/AlAs superlattices containing quantum wires also exhibit polarization anisotropy of the photoluminescence observed in the yellow-red spectral range.
1 citations