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Semiconductor Lasers (semiconductor + laser)
Selected AbstractsOrganic Lasers: The Development of Luminescent Concentrators for Pumping Organic Semiconductor Lasers (Adv. Mater.ADVANCED MATERIALS, Issue 31 200931/2009) Graham Turnbull and co-workers report on p. 3205 that a luminescent concentrator based on a coumarin dye doped polymer film can be used to reduce the pumping threshold of polymer lasers. To achieve this effect, the edge of the luminescent concentrator is placed in contact with the surface of an MEH-PPV distributed feedback laser. Intense green fluorescence from the edge of the concentrator film is then used to pump the laser (the red laser emission can be seen at the left of the cover image). [source] The Development of Luminescent Concentrators for Pumping Organic Semiconductor LasersADVANCED MATERIALS, Issue 31 2009Ying Yang A luminescent concentrator, based on coumarin dye doped polymer film, is used to reduce the pumping threshold of polymer lasers. The edge of the luminescent concentrator is placed in contact with the surface of an MEH-PPV distributed feedback laser. Intense green fluorescence from the edge of the concentrator film pumps the laser (red laser emission shown on left). [source] Indirect laser-induced fluorescence detection of diuretics separated by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5 2006Xiuhan Yang Abstract Indirect LIF detection was applied to the detection of four acidic diuretics separated by CZE. Semiconductor laser was employed to provide the stable excitation of 473 nm. With an optimized electrophoretic buffer system which contained 5 mM of triethylamine, 0.1 ,M of fluorescein, and 5% of n -butanol, fast separation of four diuretics (ethacrynic acid, chlorthalidone, bendroflumethiazide, and bumetanide) can be performed within 3 min with the detection limits of 0.2,2 ,g/mL. The impacts of buffer components including the concentrations of the electrolytes, fluorescence probe, and the organic additives were demonstrated. The method was applied for the detection of diuretics in urine. As an alternative way for the fast analysis of diuretics, this indirect detection method provided the technical support for future microchip performances, in which diuretics may be detected in the microchip by the common LIF detector without derivatization. [source] All-optical clock division with simultaneous wavelength conversion using an optically injected Fabry-Perot laser diodeMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2009Yu-Xiang Lv Abstract The authors propose and experimentally demonstrate a novel technique that uses a single Fabry-Perot laser diode (FP-LD) to perform simultaneous all-optical clock division and wavelength conversion. By utilizing the nonlinear dynamical period-one oscillation and the cross-gain modulation effect of the light injection semiconductor laser, we achieve the all optical clock frequency division of 12.36 GHz to 6.18 GHz with simultaneous wavelength conversion from 1550.24 nm to 1545.91 nm. The phase noise of the extracted optical clock is less than ,105 dBc/Hz. It was empirically found that the best clock division and wavelength conversion occurred when the injected signal power was approximately 2,2.5 times as the injected probe light power, and the range of optimum wavelength detuning was about from ,0.01 nm to 0.06 nm. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2428,2431, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24626 [source] Subtraction of scattering parameters for adiabatic intrinsic responses of semiconductor lasersMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2008S. J. Zhang Abstract Thermal effects will make chip temperature change with bias current of semiconductor lasers, which results in inaccurate intrinsic response by the conventional subtraction method. In this article, an extended subtraction method of scattering parameters for characterizing adiabatic responses of laser diode is proposed. The pulsed injection operation is used to determine the chip temperature of packaged semiconductor laser, and an optimal injection condition is obtained by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide temperature range. In this case, the scattering parameters of laser diode are measured on adiabatic condition and the adiabatic intrinsic responses of packaged laser diode are first extracted. It is found that the adiabatic intrinsic responses are evidently superior to those without thermal consideration. The analysis results indicate that inclusion of thermal effects is necessary to acquire accurate intrinsic responses of semiconductor lasers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 992,995, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23278 [source] Sensitive Explosive Vapor Detection with Polyfluorene LasersADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Ying Yang Abstract Distributed feedback organic semiconductor lasers based on polyfluorene are shown to be suitable for use as chemical sensors for the detection of nitroaromatic-based explosive vapors. The laser threshold is increased by a factor of 1.8 and the slope efficiency is reduced by a factor of 3 after exposure to the vapor. The sensing efficiency depends strongly on the excitation energy with a maximum efficiency of 85%. The temporal dynamics of the laser response to the analyte have been investigated. The laser emission falls to 60% of its initial value in 46,s. A model is developed to offer some insight into the diffusion of the vapor molecules inside the polymer layer. [source] Numerical analysis of optical feedback phenomenon and intensity noise of fibre-grating semiconductor lasersINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 3 2007Moustafa Ahmed Abstract This paper demonstrates numerical analysis of the dynamics and intensity noise of fibre-grating semiconductor lasers (FGSLs). The induced phenomenon of strong optical feedback (OFB) is analysed. The simulations are based on an improved time-delay rate equations model of a single-mode laser that takes into account the multiple round-trips of the lasing field in the fibre cavity. The analyses are performed in terms of the temporal trajectory of the laser intensity, bifurcation diagram and relative intensity noise (RIN). We explore influence of the fibre-cavity length on the dynamics and RIN. The results show that when the fibre cavity is short, the regime of strong OFB is characterized by either continuous-wave (CW) operation or periodic pulsation. The pulsation frequency is locked at the frequency separation of either the compound-cavity modes or the external fibre-cavity modes. The corresponding RIN level is close to or higher than the level of the solitary laser depending on pulse symmetry. When the fibre cavity is long, the laser exhibits unstable dynamics over wider range of OFB. Moreover, the strong-OFB pulsation becomes beating quasi-periodic at the relaxation oscillation frequency and the fibre-cavity mode-separation frequency. Copyright © 2007 John Wiley & Sons, Ltd. [source] Well-posedness, smooth dependence and centre manifold reduction for a semilinear hyperbolic system from laser dynamicsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 8 2007Mark Lichtner Abstract We prove existence, uniqueness, regularity and smooth dependence of the weak solution on the initial data for a semilinear, first order, dissipative hyperbolic system with discontinuous coefficients. Such hyperbolic systems have successfully been used to model the dynamics of distributed feedback multisection semiconductor lasers. We show that in a function space of continuous functions the weak solutions generate a smooth skew product semiflow. Using slow fast structure and dissipativity we prove the existence of smooth exponentially attracting invariant centre manifolds for the non-autonomous model. Copyright © 2006 John Wiley & Sons, Ltd. [source] Subtraction of scattering parameters for adiabatic intrinsic responses of semiconductor lasersMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2008S. J. Zhang Abstract Thermal effects will make chip temperature change with bias current of semiconductor lasers, which results in inaccurate intrinsic response by the conventional subtraction method. In this article, an extended subtraction method of scattering parameters for characterizing adiabatic responses of laser diode is proposed. The pulsed injection operation is used to determine the chip temperature of packaged semiconductor laser, and an optimal injection condition is obtained by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide temperature range. In this case, the scattering parameters of laser diode are measured on adiabatic condition and the adiabatic intrinsic responses of packaged laser diode are first extracted. It is found that the adiabatic intrinsic responses are evidently superior to those without thermal consideration. The analysis results indicate that inclusion of thermal effects is necessary to acquire accurate intrinsic responses of semiconductor lasers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 992,995, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23278 [source] Modulation bandwidth of semiconductor lasers based on coupled quantum wellsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2004M. S. Wartak Abstract The effect of well coupling on differential gain and maximum-modulation bandwidth for semiconductor lasers based on coupled quantum wells is analyzed using the K -factor method. We determine differential gain in coupled quantum wells within the self-consistent solution of the Poisson, Schroedinger, and 4 × 4 Luttinger,Kohn equations. The multiple-body effects of bandgap renormalization, coulombic scattering interactions, and a nonMarkovian distribution are also included. The analysis has been performed for coupled wells at 1.55 ,m in an InGaAsP/InP lattice-matched system grown in the [001] direction. Our results suggest that in order to maximize modulation bandwidth and differential gain, one should design structures with barrier widths larger than 40 Å. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 272,274, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20275 [source] Carrier leakage suppression utilising short-period superlattices in 980 nm InGaAs/GaAs quantum well lasersPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2004D. Lock Abstract Short-period Super Lattices (SSLs) have been proposed as a method of reducing carrier leakage in semiconductor lasers. SSLs increase the carrier confinement by increasing the effective barrier height due to the carriers being "reflected" from the SSL. Thermionically driven leakage of electrons from the quantum wells has been suggested as an important non-radiative current path in (Al)GaAs based devices which is exacerbated at high temperatures. Due to the fact that the application of high pressure causes a reduction in the zone centre ,,X minima splitting, pressure can be used to investigate the extent to which such leakage increase the threshold current. In this study, we compare devices with and without SSL layers and find direct evidence for leakage suppression in devices containing SSLs up to a temperature of 60 °C. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preface: phys. stat. sol. (c) 1/8PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2004Markus C. Amann In this special issue of physica status solidi (c) we have included 10 invited papers reviewing the current state-of-the-art and the progress achieved in materials science, semiconductor theory, novel physical mechanisms and advanced device concepts in the field of nanostructured electronic and optoelectronic semiconductor devices. All of these papers were written by previous members of the Collaborative Research Centre 348 "Nanometer-Halbleiterbauelemente: Grundlagen , Konzepte , Realisierungen" (Nanometer Semiconductor Devices: Fundamentals , Concepts , Realisations), which was funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) during the period from 1991 to 2003. In these twelve years, the researchers in this programme have carried an intense activity directed towards two main objectives. First of all, Fundamentals and Concepts of nanostructure devices and their technology were explored theoretically and experimentally including the effects of low-dimensional structures on carrier transport, optical properties and spin, as well as the enabling epitaxial and nanostructure technologies such as the cleaved-edge-overgrowth technique and the self-assembled growth of quantum dots. A second field of interest was focused towards the design and development of Novel Semiconductor Devices exploiting nanostructure technology. This comprises optical detectors and memories with nanometer lateral dimensions, microwave detectors and sources up to the 300 GHz regime, innovative tunable and surface-emitting semiconductor lasers for the wavelength range 0.9 to 2 ,m, and nitride-based resonant tunnelling diodes. Some of the device innovations have meanwhile become commercial products proving also the practical importance of this research area. The articles in this special issue relate to the projects of the last three-years' funding period from 2000 to 2003 and are organized along these two topical areas. We would like to thank the numerous reviewers for their valuable comments and the editorial staff of physica status solidi (c) for their extremely helpful support. The funding by the German Research Foundation over the full project time and the continued monitoring and advice by its representatives Dr. Klaus Wehrberger and Dr. Peter Heil are gratefully acknowledged by all previous members and co-workers of this Collaborative Research Centre. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||