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Photon statistics and dynamics of nanolasers subject to intensity feedback
摘要： Using a fully stochastic numerical scheme, we theoretically investigate the behavior of a nanolaser in the lasing transition region under the influence of intensity feedback. Studying the input-output curves as well as the second-order correlations for different feedback fractions, we obtain an insight into the role played by the fraction of photons reinjected into the cavity. Our results reveal that the transition shrinks and moves to lower pump values with the feedback strength, and irregular pulses can be generated when the feedback is sufficiently large. The interpretation of the observation is strengthened through the comparison with the temporal traces of the emitted photons and with the radio-frequency power spectra. These results provide insight into the physics of nanolasers as well as validating the use of the second-order autocorrelation as a sufficient tool for interpretation of the dynamics. This confirmation offers a solid basis for the reliance on autocorrelations in experiments studying the effects of feedback in nanodevices.
关键词： nanolasers,stochastic simulation,intensity feedback,photon statistics,autocorrelation
更新于2025-09-23 15:19:57
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Effect of Infrared Low-Intensity Laser Irradiation on Lipid Peroxidation under Conditions of Experimental Circulatory Hypoxia of Visual Analyzer
摘要： The physiological stress modeled by circulatory hypoxia activates LPO processes in various tissues. In posthypoxic period, the infrared low-intensity laser irradiation significantly decreased the chemiluminescence parameters in blood plasma, normalized the retinal levels of diene and triene conjugates, and decreased MDA in the rat brain attesting to the correcting effect of this irradiation during various types of physiological stresses.
关键词： infrared low-intensity laser irradiation,lipid peroxidation,rats,visual analyzer
更新于2025-09-23 15:19:57
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Electromagnetically induced grating in double quantum dot system
摘要： Electromagnetically induced grating (EIG) in the ladder-plus-Y double quantum dot system is modeled and the diffraction grating properties are explored in this structure. A high transmission function is obtained under the high pump field. This function is reduced under increasing the probe field due to the Kerr effect. The phase of this function depends on pumping. It is shown that the application of another two fields from the wetting layer (WL)-quantum dot (QD) type is more efficient in obtaining very high diffraction intensity. So, EIG with high diffraction intensity is obtained under a four-field application. Note that, WL-QD field effect is not studied earlier. Neglecting the WL effect reduces the transmission by five times. The diffraction intensity of this system is six times higher than that obtained from a single QD structure.
关键词： Quantum dot,Electromagnetically induced grating,Diffraction intensity
更新于2025-09-23 15:19:57
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Time-dependent 3D modeling of the thermal analysis of the high-power diode laser hardening process
摘要： In this paper, the thermal analysis of the high-power diode laser hardening process was modeled on AISI 4130 steel. Afterward, the depth and width of hardness were predicted based on the complete austenite temperature (AC3). Due to the dimensions and output beam power of the diode laser stack (DLS), it is impossible to achieve the suitable power density (103-105 W/cm2). Furthermore, the output intensity profile of the DLS is not homogeneous because of the pitch between the emitters. Thus, to achieve a suitable power density and a uniform beam profile, an optical layout was designed. The beam profile was experimentally obtained by a beam profiler at different distances from the focal plane and was compared with the modeling results. Due to the agreement between the modeling and experimental results, the intensity value of each mesh of the laser profile was extracted from the ZEMAX software. Then, for the thermal analysis of the laser hardening process (LHP), it was entered as a heat flux input into the COMSOL Multiphysics software.
关键词： Thermal analysis,Intensity profile,High power diode laser,Laser hardening,Complete austenite temperature
更新于2025-09-23 15:19:57
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A method for the statistical evaluation of the fluorescence intensity of single blinking quantum dots using a confocal fluorescence microscope
摘要： The evaluation of the fluorescence intensity of single quantum dots (QDs) using a confocal fluorescence microscope can provide an alternative approach for estimating the effects of environmental changes or surface modifications on the fluorescence intensity of single QDs. In the case of blinking QDs, irregular blinking would significantly influence the intensity evaluation results that are based on the analysis of one or a few single QDs. In this regard, statistical intensity evaluations based on a large number of single QDs would be helpful to estimate an approximate intensity value of single QDs with reduced effects of blinking on the evaluation results. Herein, we developed a convenient method to statistically evaluate the fluorescence intensity of a large number of single blinking QDs using Gaussian distribution. Based on the intensity analysis of thousands of single QDs, the fluorescence intensity of the single QDs evaluated using a confocal fluorescence microscope was approximately 4090 with little data fluctuation induced by blinking.
关键词： confocal fluorescence microscope,statistical evaluation,fluorescence intensity,single blinking quantum dots,Gaussian distribution
更新于2025-09-23 15:19:57
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Lens-to-sample distance effect on the quantitative analysis of steel by laser-induced breakdown spectroscopy
摘要： The focusing position of the laser affects the characteristics of the laser-induced plasma, which in turn influences the signal stability and the quantitative analysis of laser-induced breakdown spectroscopy. In this study, six standard alloy steels are used as the samples, and the trace elements including Si, Mn, Cr are quantitatively analyzed by internal standard method. The variations of line intensity, background noise intensity, signal-to-background ratio (SBR), detecting sensitivity and detection of limit (LOD) of the element with lens-to-sample distance (LTSD) were investigated. The results show that both the intensities of the analytical line and the background noise reached a maximum when the LTSD is 94 mm. While the corresponding SBR is relatively low. For quantitative analysis, it is observed that the change of the detection sensitivity with LTSD has the similar trend with that of SBR. That is, the detection sensitivity has a lower value when the LTSD is 94mm. However, when the LTSD changes from 93mm to 99mm, LODs of the three elements are maintained at a small value. The present results indicate that for quantitative analysis of LIBS, the intensities of the analytical line and the background noise should be comprehensively considered when optimizing the laser focusing position.
关键词： Laser-induced breakdown spectroscopy,Quantitative analysis,Line intensity,Lens-to-sample distance
更新于2025-09-23 15:19:57
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Ultra-high sensitivity temperature sensor using a fiber loop mirror based on a water-filled asymmetric two-hole fiber
摘要： Conventional practice for transformer dissolved gas analysis (DGA) is to use concentrations of several fault gases, with or without total dissolved combustible gas, for evaluating apparent fault severity. We suggest a simpler approach based on the normalized energy intensity (NEI), a quantity related directly to fault energy dissipated within the transformer. DGA fault severity scoring based on NEI is shown to be sensitive to all IEC fault types and to be more responsive to shifts in the relative concentrations of the fault gases than scoring based on fault gas concentrations. Instead of eight or more gas concentration limits, NEI scoring requires only two or three limits that can be empirically derived to suit local requirements for any population of mineral-oil-filled power transformers.
关键词： enthalpy,Dissolved gas analysis (DGA),normalized energy intensity (NEI),fault energy,transformer,fault severity
更新于2025-09-23 15:19:57
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Laser array beam propagation through liver tissue
摘要： Laser array beam propagating through mouse liver tissue is investigated. The turbulence power spectrum of the liver tissue is employed in the extended Huygens–Fresnel method to obtain an optical intensity pro?le and beam broadening at the observation point in biological liver tissue. Variations of the beam pro?le and the beam broadening are simulated based on the number of beamlets, source size, wavelength and the ring radius of the array. A biological tissue, illuminated by the laser array beam, exhibits different beam pro?les and beam spot radius variations when the number of beamlets, source size, wavelength and the ring radius of the laser array beam are varied. Examining these variations observed in the propagated optical beam and comparing them with the test cases, abnormalities such as cancer and tumor in a biological liver tissue can be diagnosed.
关键词： Optical wave propagation,Tissue turbulence,Effective beam spot radius,Optical intensity,Optical imaging
更新于2025-09-23 15:19:57
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Ultra-Wide and Flattened Optical Frequency Comb Generation Based on Cascaded Phase Modulator and LiNbO3-MZM Offering Terahertz Bandwidth
摘要： In this paper, a new technique for generation of ultra-wide and flattened optical frequency comb (OFC) based on serial cascading of a phase modulator and dual-driven Lithium-Niobate Mach Zehnder modulator (DD-LiNbO3-MZM) is proposed. Over 60 carriers were generated by carefully adjusting the RF switching voltage (RFSV) of the DD-LiNbO3-MZM and the signal frequency of the sinusoidal wave (RF) source. A low power amplified RF source with a signal driving power of ~16.9dBm is applied, and the power of CW laser is kept at 3dBm. The frequency spacing (FS) is kept at 20GHz for generating the maximum number of carriers. Nonetheless, the scheme is also tested for the FSs of 64GHz, and 32GHz. Each scenario is examined in simulation environment and the main outcomes are highlighted. The proposed scheme is comparatively simple and the FS varies with the applied RF source on the modulators. The achieved OFC lines have a tone-to-noise ratio (TNR) of over ~45dB with an undesired side mode suppression ratio of approximately 20dB. The comb lines are almost flat with a varying power deviation of around 0dB-6dB which is optimized to nearly ~0.12dB. Furthermore, the impact of the RFSV on the generated number of carriers is studied in detail. The scheme is analyzed in terms of cost efficiency, power deviations, TNR, optical signal to noise ratio, and number of achieved comb lines.
关键词： Optical Frequency Comb,Mach-Zehnder modulator,Phase modulator,Intensity modulation
更新于2025-09-23 15:19:57
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[IEEE 2019 Tenth International Conference on Intelligent Control and Information Processing (ICICIP) - Marrakesh, Morocco (2019.12.14-2019.12.19)] 2019 Tenth International Conference on Intelligent Control and Information Processing (ICICIP) - An Improved Scan Matching Method Based on Laser Reflection Intensity
摘要： High-precision localization performance of mobile robots in featureless environments plays an important role in the field of navigation. This paper describes an effective localization solution using a landmark whose surface is covered with two different materials resulting in different laser reflection intensities. Based on the landmark, a feature extraction algorithm is proposed and an improved scan matching method for mobile robot localization in featureless environments is described. Unlike traditional scan matching methods which only use geometric features, the proposed method mixes geometric information extracted from environment and laser reflection intensity extracted from the landmark to achieve accurate pose estimation. Experiments show that our method has higher precision than previous methods.
关键词： high-precision localization,scan matching,laser reflection intensity,featureless environment
更新于2025-09-23 15:19:57