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Slope Efficiency (slope + efficiency)

Distribution by Scientific Domains
Physics and Astronomy70%
Polymers and Materials Science17%

Selected Abstracts

Low-Threshold Distributed-Feedback Lasers Based on Pyrene-Cored Starburst Molecules with 1,3,6,8-Attached Oligo(9,9-Dialkylfluorene) Arms

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009
Ruidong Xia
Abstract Here, a detailed characterization of the optical gain properties of sky-blue-light-emitting pyrene-cored 9,9-dialkylfluorene starbursts is reported; it is shown that these materials possess encouragingly low laser thresholds and relatively high thermal and environmental stability. The materials exhibit high solid-state photoluminescence (PL) quantum efficiencies (>90%) and near-single-exponential PL decay transients with excited state lifetimes of ,1.4,ns. The thin-film slab waveguide amplified spontaneous emission (ASE)-measured net gain reaches 75,78,cm,1. The ASE threshold energy is found to remain unaffected by heating at temperatures up to 130,°C, 40 to 50,°C above Tg. The ASE remained observable for annealing temperatures up to 170 or 200,°C. 1D distributed feedback lasers with 75% fill factor and 320,nm period show optical pumping thresholds down to 38,65,Wcm,2, laser slope efficiencies up to 3.9%, and wavelength tuning ranges of ,40,nm around 471,512,nm. In addition, these lasers have relatively long operational lifetimes, with N1/2,,,1.1,×,105,pulses for unencapsulated devices operated at ten times threshold in air. [source]

Continuous-wave laser operation at 1.33 ,m of Nd:CNGG and Nd:CLNGG crystals

LASER PHYSICS LETTERS, Issue 3 2008
Z.B. Shi
Abstract With a laser-diode (LD) as the pump source, continuous-wave (cw) laser performance at 1.33 ,m of Nd:CNGG and Nd:CLNGG crystals was demonstrated for the first time. The maximum power of 158 mW and 141 mW from Nd:CNGG and Nd:CLNGG lasers were obtained with the corresponding optical conversion efficiencies of 1.3% and 1.5%, and slope efficiencies of 2.0% and 2.9%, respectively. The difference between the laser performance of Nd:CNGG and Nd:CLNGG crystals was also discussed. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Sensitive Explosive Vapor Detection with Polyfluorene Lasers

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
Ying 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]

Low Thresholds in Polymer Lasers on Conductive Substrates by Distributed Feedback Nanoimprinting: Progress Toward Electrically Pumped Plastic Lasers

ADVANCED MATERIALS, Issue 7 2009
Ebinazar B. Namdas
A light-emitting transistor (LEFET) architecture with a distributed feedback (DFB) resonator structure nanoimprinted into the gain medium offers a route to achieving an electrically pumped plastic laser. A 2D DFB laser provides lower lasing thresholds than a 1D DFB laser under identical conditions. The 2D DFB lasers exhibit excellent characteristics with lasing threshold and slope efficiency of 32,nJ/pulse and 1.2%, respectively. [source]

Continuous wave and passively Q-switched laser performance of the mixed crystal Nd:Lu0.15Y0.85VO4

LASER PHYSICS LETTERS, Issue 5 2010
S. Zhang
Abstract Laser characteristics of a novel mixed laser crystal Nd:Lu0.15Y0.85VO4 was investigated. It is attractive for Q-switching with high repetition rate and short pulse width due to its suitable stimulated emission cross-section and short upper level lifetime. Continuous wave (CW) output power of 8.18 W was obtained at the pump power of 18.9 W, corresponding to the optical conversion efficiency of 43.3% and the slope efficiency of 47%. In the passive Q-switching operation, the minimum pulse width attained was 7.8 ns, with the pulse repetition frequency of 23.2 kHz, with the single pulse energy and peak power estimated to be 94.8 ,J and 12.2 kW, respectively. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

8.5 W room temperature continuous wave operation of a Ho:LuAG laser

LASER PHYSICS LETTERS, Issue 12 2009
X.M. Duan
Abstract We report the continuous wave Ho:LuAG laser operated at room temperature. Using the diode-pumped Tm:YLF laser as a pumping source, maximum output power of 8.5 W at 2100 nm was obtained under the incident pump power of 18.4 W, corresponding to a slope efficiency of 51.3% and a conversion efficiency of 46.2%. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Crystal growth, optical properties, and continuous-wave laser operation of Nd3+ -doped CaNb2O6 crystal

LASER PHYSICS LETTERS, Issue 10 2009
Y. Cheng
Abstract Laser crystal Nd:CaNb2O6 with excellent quality has been grown by Czochralski technique. The effective segregation coefficient of Nd3+ was studied by X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Nd:CaNb2O6 were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10,20 cm2with a broad FWHM of 7 nm at 808 nm for E , a light polarization. The emission cross section at 1062 nm is 9.87 × 10,20 cm2. We report what we believe to be the first demonstration of the continuous-wave Nd:CaNb2O6 laser operation under diode pumping. Output power of 1.86 W at 1062 nm was obtained with a slope efficiency of 19% in the CW regime. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Laser properties of continuous-grown GdVO4/Nd:GdVO4 composite crystal

LASER PHYSICS LETTERS, Issue 9 2009
X.D. Li
Abstract Effective CW and A-O Q-switched laser operations were demonstrated firstly using a continuous-grown GdVO4/Nd:GdVO4 composite rod. A maximum CW output power of 19.2Wwas obtained with the slope efficiency of 79.6% and the maximum optical-optical efficiency of 73.0% to absorbed pump power. In A-O Q-switched operation, the pulse width of 15.0 ns, 10.6 ns, and 6.9 ns, the peak power of about 11.3 kW, 29.6 kW, and 130.4 kW were achieved at the repetition rate of 100 kHz, 50 kHz, and 10 kHz, respectively. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Actively Q-switched, diode pumped thulium laser

LASER PHYSICS LETTERS, Issue 12 2007
J.K. Jabczynski
Abstract 6 W of output power and near 50% slope efficiency with respect to absorbed pump power was demonstrated in freerunning mode for a short, 40-mm long resonator. The uncoated, with 3.5% dopant of thulium YLF rod of.3× 8 mm size wrapped with indium foil was mounted in copper heat-sink maintaining 293 K temperature of coolant water and inserted in a short, 40-mm long resonator. For pumping the fiber coupled (0.4 mm core diameter) laser diode bar at 792-nm wavelength was deployed. The fused silica acousto-optic modulator with above 80% diffraction efficiency for 25-W power of RF was taken as the Q-switch for such a laser. In the best case of Qswitching mode up to 2-mJ output energy with 20-ns pulse duration corresponding to 100-kW peak power was demonstrated for rep. rate of a few Hz. Emission wavelength was around 1904 nm for both free-running and Q-switching regimes. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Edge-pumped asymmetric Yb:YAG/YAG thin disk laser

LASER PHYSICS LETTERS, Issue 10 2007
Q. Liu
Abstract An edge-pumping scheme for a quasi-three-level solid-state laser using asymmetric crystal is reported. The scheme uses a thin disk laser configuration with the pump light incident from disk edges. The pump light propagates through the disk along the zigzag path and repeatedly passes the gain medium, thus improving the pump uniformity and absorption efficiency. A maximum output power of over 123 W was achieved from an edge-pumped composite Yb:YAG/YAG thin disk laser, with slope efficiency of 34.8% and beam quality M2 , 20. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Laser diodes semicircular side-pumped laser rod with a round-sharped output

LASER PHYSICS LETTERS, Issue 7 2006
Y. X. Guo
Abstract In order to keep the symmetric of the pump geometry and obtain a low-level, high quality laser output, the temperature of the side-pumped laser rod is more often be controlled by a water cooling system than a conduction cooling system in the diode-pumped solid-state lasers. But the use of the water cooling system increases the volume and decreases the mobility. To solve the confliction between the beam quality and the mobility of the laser system, a novel, compact and all-solid design of the pump structure is applied to the side-pumped laser system. The Nd:YAG rod is pumped by semicircular mounted LD arrays inthe pump module, and two pump modules are working together to compensate each other. Numerical calculation and experiment are performed, the output laser has a round-sharped beam with a beam waist of 5 mm and a divergence angle less than 7 mrad, and a maxim output pulse energy of 75.8 mJ is obtained under the working frequency of 20Hz, the slope efficiency is 35.8%. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Continuous-wave intracavity Raman generation in PbWO4 crystal in the Nd:YVO4 laser

LASER PHYSICS LETTERS, Issue 2 2006
V. A. Orlovich
Abstract Continuous-wave Raman generation on PbWO4 crystal placed in the cavity of an end-diode-pumped Nd:YVO4 laser is demonstrated. The Raman threshold was measured as 0.9 Wof the laser-diode power. The highest output power obtained at the first Stokes wavelength 1177 nm was 178 mW at the laser diode power of 2.3 W, corresponding to the slope efficiency of 13%. The Stokes beam quality M2 did not exceed 1.7. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

High-power narrow line width tunable cladding pumped Er:Yb co-doped fiber laser

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2006
Shu-min Zhang
Abstract A narrow line width, tunable, and highly efficient fiber laser based on Er3+/Yb3+ co-doped double-clad fiber with the maximum output power of 438 mW and a slope efficiency of ,16% has been demonstrated. By using a fiber Bragg grating (FBG) as a narrow band reflector, 3-dB line width of the output laser could be as narrow as 0.04 nm over the whole tuning range, and by compressing or stretching the FBG, wavelength tunable range of 4.0 nm was realized. In the experiment, we also found that there existed an optimum splitting ratio of the output coupler, at which the maximum output power could reach ,647 mW. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1736,1739, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21762 [source]

Analog characteristics of electroabsorption modulator for RF/optic conversion; RF gain and IMD3

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2006
Yong-Duck Chung
Abstract We design and fabricate a traveling-wave electroabsorption modulator for RF/optic conversion. The RF gain is measured with a simple RF/optic link. It is related to the optical transfer curve. The input optical power causes the change of the transfer curve so that the RF gain varies accordingly. The RF/optic conversion gain shows a close relationship with the slope efficiency of transfer curve. Linearity is also one of the important characteristics for analog applications. We evaluate the linearity of the module from the 3rd -order intermodulation distortion (IMD3). © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1151,1155, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21564 [source]

Device characteristics and metal,dielectric high reflectivity coating analysis of ,,,,1.3,µm InGaAsP/InGaAsP MQW PBH lasers

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2010
J. W. Leem
Abstract The cavity length-dependent characteristics of compressively strained InGaAsP/InGaAsP multiple quantum well planar buried heterostructure lasers operating at ,,,,1.3,µm were investigated under continuous-wave mode. The uncoated 600,µm long laser exhibits Pmax,=,33.6,mW and Ith,=,12.9,mA at 25,°C with d,/dT,=,0.35,nm/K and d,/dPe,=,0.044,nm/mW, leading to stable beam characteristics of 19.7° (parallel),×,24.1° (perpendicular). From the inverse slope efficiency versus cavity length plot, the loss parameters of internal differential efficiency (,i) and internal optical loss (,i) were extracted, i.e., ,i,=,78% and ,i,=,10.6,cm,1. The transparent current density of Jtr,=,0.12,kA/cm2 and modal gain of G,=,49.5,cm,1 were also estimated from cavity length-dependent threshold current density measurements. Metal,dielectric Au/Ti/SiO2 layers for high reflectivity (HR) coating were analyzed using theoretical calculations and experimental results. For the HR-coated 600,µm long laser with Au (150,nm)/Ti (5,nm)/SiO2 (250,nm), Pmax increased up to 61,mW at 25,°C with a reduced Ith of 10.6,mA compared to the uncoated laser, providing an HR of about 94%. [source]

Low thermal resistance, high-speed 980 nm asymmetric intracavity-contacted oxide-aperture VCSELs

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009
Y. M. Song
Abstract We demonstrated high-speed characteristics of an oxide-aperture vertical-cavity surface-emitting laser (VCSEL) with intracavity structures for both p- and n-contacts, based on InGaAs/GaAs multiple quantum wells operating at , , 980 nm, indicating a low thermal resistance (Rth). The asymmetric current injection scheme is employed for reducing current crowding around the rim of the oxide aperture. A high aluminium content undoped Al0.88Ga0.12As and GaAs distributed Bragg reflector (DBR) mirror is used for efficient heat dissipation. The VCSEL with a 7 ,m oxide aperture exhibited an output power of 2.5 mW and a threshold current of 0.8 mA with a slope efficiency of 0.39 mW/mA at 20 °C under continuous-wave operation and it still worked with 1.3 mW at 90 °C. The temperature tuning coefficient of 0.081 nm/°C and dissipated electrical power tuning coefficient of 0.104 nm/mW were observed, leading to a low Rth of 1.28 °C/mW. A high modulation bandwidth up to 13 GHz with a modulation current efficiency factor of 6.1 GHz/mA1/2 was achieved. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Lu2O3:Yb3+ ceramics , a novel gain material for high-power solid-state lasers

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2005
K. Takaichi
Abstract We have developed Yb3+:Lu2O3 ceramics with nanocrystalline technology and a vacuum sintering method. A laser diode end-pumped efficient Yb3+:Lu2O3 ceramic laser was demonstrated. A 0.7 W cw output power was obtained with the slope efficiency of ,36% at 1035 nm wavelength, and 0.95 W with the slope efficiency of ,53% at 1079 nm. We classify the Lu2O3:Yb3+ ceramics as gain medium for high-power solid-state lasers (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]