Low saturation fluence in a semiconductor saturable electroabsorber mirror operated in a self-biased regime

A semiconductor saturable absorber mirror utilizing the electroabsorption effect on a self-biased stack of extremely shallow quantum wells is proposed and analyzed theoretically and numerically. The saturation flux and recovery time of the proposed device when operated with picosecond incident pulses are shown to compare very favorably with existing all-optical constructions. (C) 2008 American Institute of Physics

Electron-conformational transformations in nanoscopic RyR channels govern both the heart's contraction and beating

We show that a simple biophysically based electron-conformational model of RyR channel is able to explain and describe on equal footing the oscillatory regime of the heart's cell release unit both in sinoatrial node (pacemaker) cells under normal physiological conditions and in ventricular myocytes under Ca$^{2+}$ SR overload.Comment: 6 pages, 3 figure

Laser diode structures with a saturable absorber for high-energy picosecond optical pulse generation by combined gain-and Q-switching

The performance of gain-switched Fabry-Perot asymmetric-waveguide semiconductor lasers with a large equivalent spot size and an intracavity saturable absorber was investigated experimentally and theoretically. The laser with a short (∼20 μm) absorber emitted high-energy afterpulse-free optical pulses in a broad range of injection current pulse amplitudes; optical pulses with a peak power of about 35 W and a duration of about 80 ps at half maximum were achieved with a current pulse with an amplitude of just 8 A and a duration of 1.5 ns. Good quality pulsations were observed in a broad range of elevated temperatures. The introduction of a substantially longer absorber section leads to strong spectral broadening of the output without a significant improvement to pulse energy and peak power

Theory of direct and indirect effect of two-photon absorption on nonlinear optical losses in high power semiconductor lasers

The effect of the transverse laser structure on two-photon absorption (TPA) related effects in high-power diode lasers is analysed theoretically. The direct effect of TPA is found to depend significantly on the transverse waveguide structure, and predicted to be weaker in broad and asymmetric waveguide designs. The indirect effect of TPA, via carrier generation in the waveguide and free-carrier absorption, is analysed for the case of a symmetric laser waveguide and shown to be strongly dependent on the active layer position. With the active layer near the mode peak, the indirect effect is weaker than the direct effect due to the population of TPA-created carriers being efficiently depleted by their diffusion and capture into the active layer, whereas for the active layer position strongly shifted towards the p-cladding, the indirect effect can become the dominant power limitation at very high currents. It is shown that for optimizing a laser design for pulsed high power operation, both TPA related effects and the inhomogeneous carrier accumulation in the waveguide caused by diffusive current need to be taken into account

Threshold and power of pulsed red‐emitting diode lasers with a bulk active layer near p‐cladding under high‐temperature operation

Threshold properties and pulsed output of AlGaInP visible-emitting lasers with an asymmetric waveguide structure and a bulk active layer are analysed. The efects of the current leakage, increased by the heating of the laser due to the proximity of the electrical pulse source and the Joule heating in and around this source are analysed. When optimising the laser design, waveguiding properties of the bulk active layer are shown to be important, leading to threshold currents decreasing, and injection efciency increasing, with active layer thickness in lasers with moderately thick (<0.1 μm) active layers

Electron-Conformational Transformations in Nanoscopic RyR Channels Governing Both the Heart's Contraction and Beating

We show that a simple biophysically based electron-conformational model of RyR channel can explain and describe on equal footing the oscillatory regime of the heart's cell release unit both in sinoatrial node (pacemaker) cells under normal physiological conditions and in ventricular myocytes under Ca2+ sarcoplasmic reticulum overload. © 2011 Pleiades Publishing, Ltd.This work was supported by the Ural Branch, Russian Academy of Sciences, project no. 09 M 14 2001

Strong Doping of the n-Optical Confinement Layer for Increasing Output Power of High- Power Pulsed Laser Diodes in the Eye Safe Wavelength Range

Abstract—An analytical model for internal optical losses at high power in a 1.5 μm laser diode with strong n-doping in the n-side of the optical confinement layer is created. The model includes intervalence band absorption by holes supplied by both current flow and two-photon absorption, as well as the direct two-photon absorption effect. The resulting losses are compared with those in an identical structure with a weakly doped waveguide, and shown to be substantially lower, resulting in a significant improvement in the output power and efficiency in the structure with a strongly doped waveguid

MODIFICATION OF RYANODINE-SENSITIVE CALCIUM RELEASE CHANNELS GATING AND CALCIUM DYNAMICS IN CARDIOMYOCYTES BY TEMPERATURE IN ELECTRON-CONFORMATIONAL THEORY

We took into account a temperature in an Electron-Conformational Model of SR-based Ca2+ Clock (ECM Clock). The results of modelling of ECM Clock show that higher temperature gives lower amplitude of cytosolic Ca2+ and higher frequency of oscillations and lower temperature destroys ECM Clock.Исследования поддержаны Программой повышения конкурентоспособности ведущих университетов РФ (постановление Правительства РФ № 211 от 16 марта 2013 г.)

High Power 1.5um Pulsed Laser Diode with Asymmetric Waveguide and Active Layer Near p-cladding

We report first experimental results on a high-power pulsed semiconductor laser operating in the eye-safe spectral range (wavelength around 1.5 lm) with an asymmetric waveguide structure. The laser has a bulk active layer positioned very close to the p-cladding in order to eliminate current-induced nonuniform carrier accumulation in the p-side of the waveguide and the associated carrier losses. Moderate doping of the n-side of the waveguide is used to strongly suppress nonuniform carrier accumulation within this part of the waveguide. Highly p-doped InP p-cladding facilitates low series resistance. An as-cleaved sample with a stripe width of 90 lm exhibits an output power of about 18 W at a pumping current amplitude of 80 A. Theoretical calculations, validated by comparison to experiment, suggest that the performance of lasers of this type can be improved further by optimization of the waveguide thickness and doping as well as improvement of injection efficiency.publishedVersionPeer reviewe