scholarly journals Оценка вклада поверхностной рекомбинации в микродисковых лазерах с помощью высокочастотной модуляции

2019 ◽  
Vol 53 (8) ◽  
pp. 1122
Author(s):  
А.Е. Жуков ◽  
Э.И. Моисеев ◽  
Н.В. Крыжановская ◽  
С.А. Блохин ◽  
М.М. Кулагина ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Small Diameter ◽  
Low Frequency ◽  
Thermal Stabilization ◽  
Frequency Component ◽  
Nonradiative Recombination ◽  
Modulation Mode ◽  
Side Walls ◽  
Small Signal Modulation

AbstractMicrodisk lasers 10–30 μm in diameter operating at room temperature without thermal stabilization and with an active region based on nanostructures of hybrid dimensionality—quantum wells–dots—are investigated. High-frequency measurements of the microlaser response are performed in the direct small-signal modulation mode, which makes it possible to establish the parameters of the operating speed and analyze their dependence on the microlaser diameter. It is found that the K factor is (0.8 ± 0.2) ns, which corresponds to optical losses of ~6 cm^–1, and no regular dependence on the diameter is observed. It is found that the low-frequency component of the damping coefficient of relaxation oscillations is inversely proportional to the diameter. This character of the dependence evidences a decrease in the carrier lifetime in small-diameter microcavities, which can be associated with the prevalence of nonradiative recombination on their side walls.

Recombination Mechanism in Short-Wavelength GaN/AlGaN Quantum Wells

2004 ◽  
Vol 831 ◽  
Author(s):  
D. Fuhrmann ◽  
T. Retzlaff ◽  
U. Rossow ◽  
A. Hangleiter
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Light Emission ◽  
Excitation Power ◽  
Ultraviolet Region ◽  
Nonradiative Recombination ◽  
Power Dependence ◽  
Recombination Mechanism ◽  
Quantum Well Structures ◽  
Internal Efficiency

ABSTRACTTo date, light emission by AlGaN-based heterostructures and LED's operating in the ultraviolet region is far less efficient than emission from longer wavelength structures based on GaInN. We have realized GaN/AlGaN quantum well structures emitting in the 360–320 nm range with peak room-temperature internal efficiencies reaching more than 20 %. From detailed studies of the temperature and excitation power dependence of the efficiency we find that excitons play a crucial role enhancing radiative recombination in such structures. Except for the peak internal efficiency, which reaches 73 % in GaInN/GaN, the overall behavior in GaN/AlGaN and GaInN/GaN is very similar, suggesting that the main difference is the nonradiative recombination mechanism.

scholarly journals Влияние саморазогрева на модуляционные характеристики микродискового лазера

2020 ◽  
Vol 46 (11) ◽  
pp. 3
Author(s):  
А.Е. Жуков ◽  
Э.И. Моисеев ◽  
А.М. Надточий ◽  
Н.В. Крыжановская ◽  
М.М. Кулагина ◽  
...  
Keyword(s):  
Room Temperature ◽  
Modulation Frequency ◽  
Small Diameter ◽  
Thermal Stabilization ◽  
The Self ◽  
Maximum Speed ◽  
Modulation Bandwidth ◽  
Heating Effect ◽  
Self Heating ◽  
High Bias

The performance of quantum dot microdisk lasers operating at room temperature without thermal stabilization was experimentally investigated, and the highest modulation bandwidth of microdisks of various diameters was calculated. It is shown that taking into account the self-heating effect of the microlaser at high bias currents, which manifests itself in a decrease in the maximum modulation frequency and in an increase in the current at which the maximum speed is reached, allows us to describe the experimental data well. Self-heating effect has the greatest impact on microlasers of small diameter (less than 20 µm).

scholarly journals Role of dislocations in nitride laser diodes with different indium content

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agata Bojarska-Cieślińska ◽  
Łucja Marona ◽  
Julita Smalc-Koziorowska ◽  
Szymon Grzanka ◽  
Jan Weyher ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Defect Density ◽  
Laser Diodes ◽  
Diffusion Path ◽  
Vapour Phase ◽  
Indium Content ◽  
Nonradiative Recombination ◽  
Light Emitters ◽  
Vapour Phase Epitaxy

AbstractIn this work we investigate the role of threading dislocations in nitride light emitters with different indium composition. We compare the properties of laser diodes grown on the low defect density GaN substrate with their counterparts grown on sapphire substrate in the same epitaxial process. All structures were produced by metalorganic vapour phase epitaxy and emit light in the range 383–477 nm. We observe that intensity of electroluminescence is strong in the whole spectral region for devices grown on GaN, but decreases rapidly for the devices on sapphire and emitting at wavelength shorter than 420 nm. We interpret this behaviour in terms of increasing importance of dislocation related nonradiative recombination for low indium content structures. Our studies show that edge dislocations are the main source of nonradiative recombination. We observe that long wavelength emitting structures are characterized by higher average light intensity in cathodoluminescence and better thermal stability. These findings indicate that diffusion path of carriers in these samples is shorter, limiting the amount of carriers reaching nonradiative recombination centers. According to TEM images only mixed dislocations open into the V-pits, usually above the multi quantum wells thus not influencing directly the emission.

Low threshold, room temperature pulsed and quasi-continuous lasing in optically pumped CdZnTe/ZnTe quantum wells

1993 ◽  
Vol 22 (5) ◽  
pp. 479-484 ◽  
Author(s):  
R. D. Feldman ◽  
T. D. Harris ◽  
J. E. Zucker ◽  
D. Lee ◽  
R. F. Austin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Room Temperature ◽  
Optically Pumped ◽  
Low Threshold

The Lightning Electromagnetic Pulse Coupling Effect Inside the Shielding Enclosure With Penetrating Wire

Frequenz ◽  
2017 ◽  
Vol 71 (11-12) ◽  
Author(s):  
Xue Jiao ◽  
Bo Yang
Keyword(s):  
Electromagnetic Pulse ◽  
Coupling Effect ◽  
Fdtd Method ◽  
Current Source ◽  
Low Frequency ◽  
Frequency Component ◽  
Lightning Current ◽  
Proper Size ◽  
Practical Engineering ◽  
Difference Time

AbstractTo study the lightning electromagnetic pulse (LEMP) coupling and protection problems of shielding enclosure with penetrating wire, we adopt the model with proper size which is close to the practical engineering and the two-step finite-difference time-domain (FDTD) method is used for calculation in this paper. It is shown that the coupling voltage on the circuit lead inside the enclosure increases about 34 dB, when add 1.0 m long penetrating wire at the aperture, comparing with the case without penetrating wire. Meanwhile, the waveform, has the same wave outline as the lightning current source, shows that the penetrating wire brings a large number of low frequency component into the enclosure. The coupling effect in the enclosure will reduce greatly when penetrating wire has electrical connection with the enclosure at the aperture and the coupling voltage increase only about 12 dB than the case without penetrating wire. Moreover, the results show that though the waveguide pipe can reduce the coupling effect brought by the penetrating wire, the exposing part of penetrating wire can increase the coupling when the penetrating wire outside the enclosure is longer than the waveguide pipe and the longer the exposing part is, the stronger the coupling is.

Low-frequency component electric microfield distributions in plasmas governed by W. Ebeling potential

2021 ◽  
Author(s):  
Sara Kobbi ◽  
Salima Guerricha ◽  
Smaïl Chihi ◽  
Abdallah Bekkouche ◽  
Mohammed Tayeb Meftah
Keyword(s):  
Low Frequency ◽  
Frequency Component

A Raman study of B203 through the liquid-glass transition range

1992 ◽  
Vol 02 ◽  
pp. C2-265-C2-270
Author(s):  
A. K. HASSAN ◽  
L. M. TORELL ◽  
L. BORJESSON
Keyword(s):  
Glass Transition ◽  
Correlation Length ◽  
Room Temperature ◽  
Vibrational Mode ◽  
Low Frequency ◽  
Boson Peak ◽  
Transition Range ◽  
Structural Correlation ◽  
Raman Study ◽  
Correlation Range

The low frequency Raman spectrum of B203 and the boroxol ring vibrational mode at 808 cm-1 have been studied from room temperature to 1273 K as the glass transforms to a melt. Both the low frequeney "boson" peak and the boroxol mode are markedly influenced by the glass transition. Raising the temperature above Tg the strength of the 808 cm-1 mode decreases linearly indicating the Similar behavior of the boroxol ring concentration. The boson peak shows a different temperature behavior, which mirrors that of the sound velo city. The structural correlation length demostrates the same correlation range in the liquid and the glass. The results, when compared with neutron diffraction measurements contradict a recently proposed relation between the "boson correlation length" and the position of the first sharp diffraction peak of the structure factor.

scholarly journals Electron acoustic solitons in the Earth's magnetotail

2004 ◽  
Vol 11 (2) ◽  
pp. 215-218 ◽  
Author(s):  
S. G. Tagare ◽  
S. V. Singh ◽  
R. V. Reddy ◽  
G. S. Lakhina
Keyword(s):  
Electron Beam ◽  
Small Amplitude ◽  
Low Frequency ◽  
Frequency Component ◽  
Magnetized Plasma ◽  
Cold Electron ◽  
Ion Plasma ◽  
Electron Acoustic ◽  
Two Temperature ◽  
Perpendicular Polarization

Abstract. Small amplitude electron - acoustic solitons are studied in a magnetized plasma consisting of two types of electrons, namely cold electron beam and background plasma electrons and two temperature ion plasma. The analysis predicts rarefactive solitons. The model may provide a possible explanation for the perpendicular polarization of the low-frequency component of the broadband electrostatic noise observed in the Earth's magnetotail.

scholarly journals The Tangential Force Affecting the Radial Baffles in a Stirred Vessel: Analysis of the Macro-instability Related Component

10.14311/450 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
P. Hasal ◽  
I. Fořt ◽  
J. Kratěna
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Tangential Force ◽  
Low Frequency ◽  
Frequency Component ◽  
Relative Magnitude ◽  
Tangential Component ◽  
Vertical Position ◽  
Total Force ◽  
Rushton Turbine

Experimental data obtained by measuring the tangential component of the force affecting radial baffles in a flat-bottomed cylindrical mixing vessel stirred with a Rushton turbine impeller is analysed. Spectral analysis of the experimental data demonstrated the presence of its macro-instability (MI) related low-frequency component embedded in the total force. Two distinct dimensionless frequencies (both directly proportional to the impeller speed of rotation N) of the occurence of the MI component were detected: a lower frequency of approximately 0.025N and a higher frequency of about 0.085N. The relative magnitude QMI of the MI-related component of the total tangential force was evaluated by a combination of proper orthogonal decomposition (POD) and spectral analysis. The values of magnitude QMI varied in the interval [rom approximately 0.05 to 0.30. The magnitude QMI takes maximum values at low Reynolds number values (in laminar and transitional regions). In the turbulent region (ReM >20000) the QMI value is low and practically constant. The dependence oj the QMI values on vertical position in the vessel is only marginal. The results suggest that the magnitude of the MI component of the force is significantly influenced by the liquid viscosity and density.

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