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2016
Volume: 43 Issue 2
36 Article(s)
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[in Chinese]
Study on Entropy Squeezing of the Atom in an Atom-Cavity-Optomechanical System
Liao Qinghong, Zheng Qinghua, Yan Qiurong, Liu Ye, and Zhang Qi
Using the theory of information entropy squeezing, the entropy squeezing of a two-level atom in an atomcavity- optomechanical system is investigated. The influences of the coherent angles of the atom, the coupling coefficient between the cavity field and the mechanical mode, and the relative phase of the two atom levelUsing the theory of information entropy squeezing, the entropy squeezing of a two-level atom in an atomcavity- optomechanical system is investigated. The influences of the coherent angles of the atom, the coupling coefficient between the cavity field and the mechanical mode, and the relative phase of the two atom level on the entropy squeezing of the atom are discussed. It is shown that the squeezing amplitude, squeezing frequency and squeezing direction of the atomic information entropy squeezing can be controlled by choosing the suitable coherent angle of the atom, coupling coefficient between the cavity field and the mechanical mode and the relative phase of the two atom level, respectively; and the atomic optimal entropy squeezing states in the system can be prepared by controlling the coherence angle of the atom. The proposal may provide a theoretical way to control entropy squeezing of the atom in the atom-cavity-optomechanical system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 218001 (2016)
Research Article
Deformable Mirror Eigen-Modes Based Wavefront Sensorless Adaptive Optics System for Point-Like Target
Wang Rui, and Dong Bing
For point-like target, a wavefront sensorless adaptive optics correction method using deformable mirror (DM) eigen- modes is proposed and studied by simulation and experiment. A set of DM eigen- modes whose derivatives are orthogonal with each other is derived from the influence function matrix of DM to replace traditiFor point-like target, a wavefront sensorless adaptive optics correction method using deformable mirror (DM) eigen- modes is proposed and studied by simulation and experiment. A set of DM eigen- modes whose derivatives are orthogonal with each other is derived from the influence function matrix of DM to replace traditional Lukosz modes. The metric function is set as the mean square radius of far-field spot. The required correction amount of each mode is directly solved from the relationship between coefficients of DM eigen-modes and the metric function value. In the simulation,the correction accuracy using the two modes mentioned above is compared and the effect of modal bias coefficient variation on correction accuracy is analyzed. Closed-loop correction results for different aberration level are also given. The experimental system is set up based on a 37- channel DM. Experimental results show that low- order aberrations can be effectively corrected by the algorithm and the correction accuracy of DM eigen-modes is better than Lukosz modes..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 212001 (2016)
Modeling and Analysis of Beam Wander in Maritime Atmospheric Turbulence
Wang Hongxing, Wu Xiaojun, and Song Bo
Beam wander is an important effect when a beam propagates in atmospheric turbulence. Based on the marine atmospheric refractive index fluctuation power spectrum, a new theoretical expression is developed for a horizontal propagation path in maritime atmospheric environment. In order to validate the model, a set of measBeam wander is an important effect when a beam propagates in atmospheric turbulence. Based on the marine atmospheric refractive index fluctuation power spectrum, a new theoretical expression is developed for a horizontal propagation path in maritime atmospheric environment. In order to validate the model, a set of measurements of beam wander for a collimated Gaussian beam is carried out using CCD technique during multiple laser transmissions under the sea surface environment in Yantai region, and the experiments are conducted at different times and various ranges. By comparing the theoretical value with measured value under the weak fluctuation condition, the results show that the relative errors between them are below16%, and the estimation given by the new theoretical expression generally provides a good fit with the data. According to the conclusion of this paper, the beam wander in the maritime atmospheric turbulence can be more accurately predicted..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 213001 (2016)
Biomedical Photonics and Laser Medicine
Study on Photoacoustic Noninvasive Detection for Blood Glucose Concentration Based on Tunable Pulsed Laser
Ren Zhong, Liu Guodong, and Huang Zhen
A preliminary research of noninvasive monitoring of blood glucose concentration is performed using the photoacoustic detection technique, and a noninvasive photoacoustic detection system is established. A tunable pulsed laser is used as the excitation source and a confocal ultrasonic transducer is used to capture the pA preliminary research of noninvasive monitoring of blood glucose concentration is performed using the photoacoustic detection technique, and a noninvasive photoacoustic detection system is established. A tunable pulsed laser is used as the excitation source and a confocal ultrasonic transducer is used to capture the photoacoustic signal of glucose concentrations. The pre-amplifier, data transmission based on GPIB-USB bus and virtual instruments developing software LabVIEW are used in this system. The time-resolved photoacoustic signals for the glucose solutions with concentration from 0 mg/dL to 300 mg/dL are acquired based on the established photoacoustic detection system. The glucose solutions with different concentrations are scanned by the tunable pulsed laser with output wavelength from 1300 nm to 2300 nm and with interval of 10 nm, and the photoacoustic peak-to-peak values are obtained. In order to obtain the characteristic wavelengths of the glucose solution, the difference spectrum algorithm and the first order differential derivative are used. The mathematical correction model between glucose concentrations and photoacoustic peak-to-peak values is established by means of linear least square fitting algorithm for the optimized characteristic wavelengths, and the glucose concentrations are inverted. Two better characteristic wavelengths are chosen based on the minimum root mean square error..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 204001 (2016)
Novel Illumination Design of Acoustic Resolution Photoacoustic Microscopy System
Zeng Guang, Shi Yan, Song Liang, and Liu Chengbo
Imaging depth of acoustic resolution photoacoustic microscopy is capable of reaching the centimeter level. There are several drawbacks regarding to the mainstream illumination designs of current acoustic resolution photoacoustic microscopy systems, e.g. switch between bright field illumination and dark field illuminatiImaging depth of acoustic resolution photoacoustic microscopy is capable of reaching the centimeter level. There are several drawbacks regarding to the mainstream illumination designs of current acoustic resolution photoacoustic microscopy systems, e.g. switch between bright field illumination and dark field illumination is not available, and the utilization efficiency of laser energy is very low. Therefore, the application of the system is limited. A novel optical illumination design has been proposed to overcome these limitations. A convex lens is applied to focus the diverging ring-shape light before it is reflected by the optical condenser, as a result, the ultimate laser spot on the sample surface can be smaller. The Monte Carlo simulation results show that laser fluence within the volume of effective ultrasound detection has been improved by as much as 6 times, and therefore the intensity of photoacoustic signals can be linearly increased as well. On the other hand, the tuning range of optical focus depth of the system has also been expanded, and after specific tuning, optimal photoacoustic signals can be obtained within different kinds of samples..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 204002 (2016)
Handheld Spectral Domain Optical Coherence Tomography for in vivo Tooth Imaging
Liu Hao, Gao Wanrong, and Chen Chaoliang
Optical coherence tomography (OCT) is a non-invasive high resolution cross-sectional imaging method with high sensitivity. A simple handheld spectral- domain optical coherence tomography (SDOCT) system is developed for imaging tooth tissues. The design of the handheld OCT probe is described in detail, and the lateral sOptical coherence tomography (OCT) is a non-invasive high resolution cross-sectional imaging method with high sensitivity. A simple handheld spectral- domain optical coherence tomography (SDOCT) system is developed for imaging tooth tissues. The design of the handheld OCT probe is described in detail, and the lateral scanning is realized by using a scanning mirror. The handheld OCT probe is characterized by its compact size and portable feature, making it easier for in vivo tooth imaging. The system is used for imaging of in vitro and in vivo tooth tissues. The enamel, dentin and the interface between them can be clearly observed in the high-resolution tomographic images..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 204003 (2016)
Holography and Information Processing
Method of Color Holographic Stereogram Generation Based on Fourier Transformation
Wang Jiaojiao, Yu Jia, Liu Huiping, Cheng Kai, and Wang Jincheng
An automatic method of making color coded synthesized Fourier transform hologram is proposed. The images of the three-dimensional model are processed by the principle of synthesized holography and the pseudo color coding method. The processed images are displayed by a spatial light modulator (SLM). The light, through tAn automatic method of making color coded synthesized Fourier transform hologram is proposed. The images of the three-dimensional model are processed by the principle of synthesized holography and the pseudo color coding method. The processed images are displayed by a spatial light modulator (SLM). The light, through the SLM and the Fourier transform optical path and the lens with a large numerical aperture, forms a point pixel on the spectrum plane. By a computer and the program control systems, a large-format color-coded large-viewing angle rainbow hologram is produced pixel by pixel automatically..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 209001 (2016)
Using Wavefront Plane to Improve Imaging Resolution of Holographic Stereogram
Huang Yingqing, Zhao Kai, Jiang Xiaoyu, and Yan Xingpeng
Because of the low imaging resolution of holographic stereogram, a method using wavefront plane is proposed to improve imaging quality. The resolution limit of holographic stereogram is mainly affected by spatial sampling, angular sampling and diffraction. The influences due to these factors are analyzed with mathematiBecause of the low imaging resolution of holographic stereogram, a method using wavefront plane is proposed to improve imaging quality. The resolution limit of holographic stereogram is mainly affected by spatial sampling, angular sampling and diffraction. The influences due to these factors are analyzed with mathematical equations. Supposing that the distance between hologram and human eyes is about 600 mm, the relationship between imaging resolution limit and depth of three-dimensional scene or Hogel size is provided according to acuity of human eyes. The depth limit of three-dimensional scene and optimal Hogel size are 12.80 mm and 90 μm, respectively, if the wavelength is 632.8 nm. A wavefront plane which is decided by depth limit is set. The experiments are performed with two three-dimensional scenes to evaluate the proposed method. With numerical simulation method, the tank model which has complicate structures is reproduced. The elaborate features of tank model at every depth are accurately obtained. A teapot model is optically reconstructed with holographic three-dimensional display system based on spatial light modulator. The three-dimensional cues such as depth and gloss are well provided in the reconstructed images..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 209002 (2016)
Laser Manufacturing
Effect of Silicon and Aluminum Addition on Microstructure and Properties of MoFeCrTiW High-Entropy Alloy Coating
Zhou Fang, Liu Qibin, and Zheng Bo
In order to improve the wear resistance and high-temperature oxidation resistance of materials surface, MoFeCrTiWSixAly (x=0 or 1 and y=0 or 1) high-entropy alloy coatings, named MoFeCrTiWSixAly high-entropy alloy (HEA) coatings, are fabricated on Q235 steel by laser cladding. The effect of silicon and aluminum on the In order to improve the wear resistance and high-temperature oxidation resistance of materials surface, MoFeCrTiWSixAly (x=0 or 1 and y=0 or 1) high-entropy alloy coatings, named MoFeCrTiWSixAly high-entropy alloy (HEA) coatings, are fabricated on Q235 steel by laser cladding. The effect of silicon and aluminum on the microstructure, phases, wear resistance and high- temperature oxidation resistance are researched by X- ray diffraction (XRD), scanning electron microscopy (SEM) and wear tester. The results show that the main phase of MoFeCrTiWSixAly HEA coatings is BCC structure. With the addition of silicon and aluminum, the lattice constants of BCC structure are all reduced. When x=0 and y=1, the coating is composed of single BCC structure, its microstructure is fine dendrites, but its wear resistance is lower. When x=1 and y=0 or 1, there is few intermetallic compound in the coatings and its wear resistance increases. MoFeCrTiWSixAly HEA coatings exhibit higher oxidation resistance at 800 ℃. Adding silicon and aluminum into coatings can further improve the high-temperature oxidation of coatings..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203002 (2016)
Microstructures of Heat Treatment and Properties of TA15 Titanium Alloy Formed by Technology of Laser Rapid Forming Combined with Continuous Point Forging
Xi Mingzhe, Liu Jingbo, Zhao Yi, and Gao Shiyou
A thick-wall part of TA15 titanium alloy is formed by the technology of laser rapid forming combined with continuous point forging. The influence of different annealing temperatures on the microstructures and the tensile properties test at room temperature of the TA15 alloy part formed by the technology of laser rapid A thick-wall part of TA15 titanium alloy is formed by the technology of laser rapid forming combined with continuous point forging. The influence of different annealing temperatures on the microstructures and the tensile properties test at room temperature of the TA15 alloy part formed by the technology of laser rapid forming combined with continuous point forging is investigated. The analysis of size of the plastic deformation zone formed by continuous point forging and the microstructure formation mechanism of the as-formed TA15 alloy part is given. The reason that the lamellar microstructure of the as- formed TA15 alloy part transform into the equiaxed microstructure is also explained. The results show that the volume fraction of equiaxed αgrain in the annealed structure of TA15 alloy and the size of the equiaxed α grain increase with annealing temperature increasing. The results also show that the strength of the annealed TA15 alloy reduce, and at the same time its ductility increases with annealing temperature increasing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203001 (2016)
Microstructure Evolution and Mechanical Properties of 5CrNi4Mo Die Steel Parts by Selective Laser Melting Additive Manufacturing
Chen Hongyu, Gu Dongdong, Gu Ronghai, Chen Wenhua, and Dai Donghua
The 5CrNi4Mo die steel is successfully prepared by selective laser melting (SLM) additive manufacturing technology. The mechanism of the phase transformation is investigated and the influence of the applied laser linear energy density h (the ratio of laser power to scan velocity) on densification, microstructure, and mThe 5CrNi4Mo die steel is successfully prepared by selective laser melting (SLM) additive manufacturing technology. The mechanism of the phase transformation is investigated and the influence of the applied laser linear energy density h (the ratio of laser power to scan velocity) on densification, microstructure, and mechanical properties of SLM-processed parts is studied. It shows that a high h results in the formation of residual pores and lowers the densification level, caused by severe balling phenomenon. A low h causes the limited wetting ability and low densification level. When h is optimized at 258.3 J/m, the SLM-processed parts have an improved densification level of 98.12% without apparent process defects. The laser-induced large solidification rate leads to the martensitic transformation. Alloying elements such as Mn, Ni, and Cr in the original powder can stabilize the undercooling austenite and lower the critical cooling rate of martensite transformation, ensuring the successful process of martensite transformation. The microstructures of martensite are further refined with decreasing h. When h is 193.8 J/m , high microhardness of 689.5 HV0.2, low friction coefficient of 0.44 and wear rate of 2.3×10-5 mm3/(N?m) are obtained for the SLM-processed parts..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203003 (2016)
Thermal Properties and Mechanical Properties of Selective Laser Melting Different Layer Thicknesses of Ni Powder
Yan Anru, Yang Tiantian, Wang Yanling, Ma Zhihong, Du Yun, and Wang Zhiyong
In order to solve the problem of low production efficiency in making heat sink use the commercial selected laser melting (SLM) equipment while keeping good thermal properties and mechanical properties , SLM technology is used to build Ni samples with different (20/40/60 μm ) powder layer thicknesses. The relative densiIn order to solve the problem of low production efficiency in making heat sink use the commercial selected laser melting (SLM) equipment while keeping good thermal properties and mechanical properties , SLM technology is used to build Ni samples with different (20/40/60 μm ) powder layer thicknesses. The relative density, microstructure, thermal conductivity, thermal expansion coefficient and tensile properties of the samples are presented. Beyond the layer thickness threshold of the laser melting, the melting track is spheroidizing line. Within the layer thickness range can be melted, the samples can be nearly full densification. With increasing layer thickness from 20 μm to 40 μm，the primary dendrite spacing increases from about 347 nm to 635 nm. Thermal conductivity decreasing from 99.28 W/K ·m at 20 μm to 92.48 W/K ·m at 40 μm. Increasing from 25 ℃ to 100℃ ，the thermal expansion coefficient from 11.02×10-6 m/(m·℃) to 12.9×10-6 m/(m·℃) at 40 μm layer thickness, lower than 11.42× 10-6 m/(m·℃) to 13.4×10-6 m/(m·℃) at 20 μm. Tensile strengths of SLMed Ni samples are much higher than those of wrought Ni regardless of layer thickness and building direction. The production efficiency of using SLM technology form heat sink at 40 μm increases 34.6% compared with 20 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203004 (2016)
Study of Nanosecond Laser Ablation on Aluminum and Stainless Steel Targets
Han Fengming, Xu Shizhen, Song Wenliang, Xiang Xia, Liu Chunming, Miao Xinxiang, and Yuan Xiaodong
Nanosecond laser damage of several aluminum and stainless steel are investigated, which materials are commonly used in the target chamber of laser drive inertial confinement fusion (LICF) device. The experimental data on mass removal and ablation depth during 1064 nm, 8 ns fundamental frequency laser ablation are measuNanosecond laser damage of several aluminum and stainless steel are investigated, which materials are commonly used in the target chamber of laser drive inertial confinement fusion (LICF) device. The experimental data on mass removal and ablation depth during 1064 nm, 8 ns fundamental frequency laser ablation are measured. The results show that the aluminum is ablated obviously when the laser fluence is greater than 1.0 J/cm2. The ablation rate of aluminum increased slowly, which has an average value of 2.31±0.89 μg/cm2/shot under laser fluence of 1.2~ 5.2 J/cm2. Furthermore, the ablation depth of aluminum increases with the increase of laser fluence, while that of stainless steel increases at first and then decreases. Aluminum alloy′s ablation depth is significantly higher than that of stainless steel. The ablation mechanism is discussed. The 1064 nm laser absorption of stainless steel is much higher than that of aluminum, which effects the laser energy deposition processes. This study is very helpful to LICF target chamber materials′ selection and laser drilling or cutting of the metals..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203005 (2016)
Influence of the Welding Conditions on Weld Defects in Double-Sided Laser Beam Welded T-Joints of Ti-6Al-4V Alloy
Ma Xuyi, Gong Shuili, Zhang Jiuxing, Yang Jing, and Lu Wei
The T-joints of Ti-6Al-4V alloy are fabricated by double-sided synchronized laser beam welding with the homologous filler wire. The influence of the welding conditions on weld defects such as lack of fusion and porosity are investigated. Results show that the lack of fusion defects are determined by the laser power, weThe T-joints of Ti-6Al-4V alloy are fabricated by double-sided synchronized laser beam welding with the homologous filler wire. The influence of the welding conditions on weld defects such as lack of fusion and porosity are investigated. Results show that the lack of fusion defects are determined by the laser power, welding speed, laser incident angle and position. With larger enough welding heat input (higher laser power, and slower welding speed), the lower laser incident angle and higher laser incident position are required to avoid the lack of fusion defects. The quantity of plasma/metal vapor above the molten pool for weld seam with the lack of fusion defects is larger than that of the weld seam without the defects under a certain laser power. The porosity defects in the welded T-joints are mainly the type of keyhole porosity defects under different welding conditions, and the higher welding speed is helpful to decrease the porosity defects under a certain laser power..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203006 (2016)
Effect of Tungsten Powder Particle Size and Shape on Consolidation and Microstructure of W-xCu Composites by Selective Laser Melting
Yan Anru, Yang Tiantian, Wang Yanling, Ma Zhihong, Du Yun, and Wang Zhiyong
In order to manufacture tungsten-copper complicate parts with high precision and densification, two different characterizations of tungsten powder balled with copper powder are manufactured by selective laser melting (SLM). The dimensional accuracy, surface morphology and microstructure of specimens are studied. The coIn order to manufacture tungsten-copper complicate parts with high precision and densification, two different characterizations of tungsten powder balled with copper powder are manufactured by selective laser melting (SLM). The dimensional accuracy, surface morphology and microstructure of specimens are studied. The composite powder containing irregular tungsten powder with 50=5 μm causes non-uniform rolling powder and serious sparks occur in sintering process. With the increasing of mass content of W from 60% to 75%, the height shrinkage increases from 70 μm to 220 μm, the length and width increase from 50 μm to 150 μm, from 70 μm to 150 μm, respectively. The surface morphology evolves from adhered debris to balling phenomenon, pores and W particle agglomerate exist in the microstructures. The composite powder containing regular tungsten powder with 50=20 μm shows uniform rolling powder process and no sparks occur in sintering. With the increasing of mass content of W from 60% to 75%, the height shrinkage increases from 70 μm to 220 μm, the length and width increase from 20 μm to 50 μm, the surface morphology evolves from sound to slightly melt fracture and the particle rearrangement is obvious. The regular tungsten powder with 50=20 μm is more applicable to manufacturing WCu components by selective laser melting than the irregular tungsten powder with 50=5 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203007 (2016)
Thermal Relaxation of Residual Stress and Grain Evolution in Laser Peening IN718 Alloy
Zhang Haifeng, Huang Shu, Sheng Jie, Xu Suqiang, Han Yuhang, and Zhou Jianzhong
In order to explore the thermal relaxation behavior of residual stress induced by laser peening on the surface of Nickel- based alloy, a single laser peening treatment is conducted on the surface of IN718 samples, followed by a series of thermal insulation tests conducted on these treated samples. Then the changes of tIn order to explore the thermal relaxation behavior of residual stress induced by laser peening on the surface of Nickel- based alloy, a single laser peening treatment is conducted on the surface of IN718 samples, followed by a series of thermal insulation tests conducted on these treated samples. Then the changes of the residual stress, full width at half maximum(FWHM) and grain evolution feature at various test temperatures and exposure time are analyzed. The results show that laser peening can induce compressive residual stress at treated region, enhance the magnitude of FWHM and obviously refine the grains in the near-surface of the material. During the thermal insulation tests, the relaxation magnitude of residual stress is positively correlated with the test temperature and the exposure time. The relaxation speed of residual stress appear to be relatively high during the initial period of exposure, and then slow down with the increases of exposure time. After being exposing by 300 min at 800 ℃, the residual stress relax at a maximum rate of 82.14%. When the test temperature is constant, there is an increase in FWHM value as the exposure time increase. At the test temperature of 600 ℃, the value change of FWHM is found to be slight. After being exposing by 300 min at 600 ℃ , the grain size is still small, which means that the grain refinement effect is still obvious. However, at the test temperature of 800 ℃, the grain grow rapidly so that after being exposing by 300 min, the grain refinement effect almostly disappear..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 203008 (2016)
Laser Physics
Compound Cavity ArF Excimer Laser with High Efficiency
Fan Yuanyuan, Zhou Yi, Liu Guangyi, Song Xingliang, Shan Yaoying, Wang Qian, and Zhao Jiangshan
ArF excimer lasers characterized by short wavelength and high photon energy have important applications in the field of integrated circuit lithography, material processing, laser medicine, and so on. Structure of the compound cavity 193 nm ArF excimer laser is designed based on the linewidth narrowing techniques. PrincArF excimer lasers characterized by short wavelength and high photon energy have important applications in the field of integrated circuit lithography, material processing, laser medicine, and so on. Structure of the compound cavity 193 nm ArF excimer laser is designed based on the linewidth narrowing techniques. Principles of the compound cavity laser are theoretically analyzed. Based on the characteristics of long cavity length in excimer laser system, the solutions for achieving effective mode-locking in compound cavity are proposed and experimentally verified. The laser output with nearly the same linewidth as the narrow-band cavity with dispersive elements and 4.02 times large energy is obtained. The laser efficiency and the energy stability are greatly improved as well..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202001 (2016)
Linearized Swept Laser Source Generation Based on Pre-Distortion and Optical Phase-Locked Loop
Xu Yan, Qin Jie, Xie Weilin, Zhou Qian, Dong Yi, and Hu Weisheng
Linearly frequency-swept laser source is widely used in high spatial resolution, precision and dynamic range light measuring and optic fiber sensor. However, the frequency sweep nonlinearity and the phase noise of the laser source limit the system spatial resolution, precision and dynamic range. The mechanism of the noLinearly frequency-swept laser source is widely used in high spatial resolution, precision and dynamic range light measuring and optic fiber sensor. However, the frequency sweep nonlinearity and the phase noise of the laser source limit the system spatial resolution, precision and dynamic range. The mechanism of the nonlinearity and phase noise in frequency-swept distributed feedback (DFB) semiconductor laser is analyzed, and propose the combination of pre-distortion and optical phase-locked loop to overcome the nonlinearity of the frequency sweep and suppress the phase noise of the laser source. Chirp of 50 GHz is achieved where the root mean square frequency error is less than 263 kHz. And the performance of the frequency- swept laser source linearity and coherence enhancement is demonstrated..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202002 (2016)
Efficient Methods of Green Output by Second Harmonic Generation with Short Pulse Broad-Band Laser
Zhang Xin, Zhang Hengli, Mao Yefei, and Sang Sihan
The effect of the role on the second harmonic generation of the Q-switched broadband optical fiber laser are simulated by using the methods of grating angular spectral dispersion (ASD), prism ASD, and crystal cascade scheme. LBO crystal type I phase is used to match, by numerically solving the three wave coupling equatThe effect of the role on the second harmonic generation of the Q-switched broadband optical fiber laser are simulated by using the methods of grating angular spectral dispersion (ASD), prism ASD, and crystal cascade scheme. LBO crystal type I phase is used to match, by numerically solving the three wave coupling equations of Gauss beam, the incident light frequency width, focal position, focal spot size and crystal thickness influence on the conversion efficiency are obtained, and the parameters of crystal is optimized. The calculation results show that the second harmonic generation (SHG) efficiency is only 17% with the laser bandwidth of 5 nm; the use of the grating ASD can achieve frequency doubling efficiency of more than 70% in a large spectral range; the compensation of the prism is smaller, while can improve the efficiency by 50%; three crystal cascade can make the efficiency increased by 130%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202003 (2016)
980 nm High-Power Fundamental Mode Distributed-Feedback Laser
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As the pumping source of lasers, 980 nm high-power laser diodes are of great importance. However, these laser diodes have some shortcomings, such as broad spectral width and low beam quality which lower the pumping efficiency and affect the stability of laser diodes. In order to improve the pumping efficiency of high-pAs the pumping source of lasers, 980 nm high-power laser diodes are of great importance. However, these laser diodes have some shortcomings, such as broad spectral width and low beam quality which lower the pumping efficiency and affect the stability of laser diodes. In order to improve the pumping efficiency of high-power semiconductor laser, the linewidth should be narrowed and the beam quality should be increased. The 980 nm highpower distributed-feedback laser (DFB) is studied by fabricating a first order grating into the laser to realize the narrow linewidth, wavelength stability output and optimizing the condition of the ridge waveguide to get the fundamental mode output. The fabricated laser diode with 1000 μm cavity length has a threshold current of 6 mA, slope efficiency of 0.71 W/A, maximum stable output of 130 mW. The thermal drift coefficient of wavelength on this DFB laser is 0.064 nm/K. When measuring the far-field divergence angle, fast axis divergence angle is 34° and slow axis divergence angle is 6.3°..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202004 (2016)
Supercontinuum Generation using Resonator Cavity of Q-Switched Fiber Laser
Li Siyuan, Ge Tingwu, Sun Chang, Gao Jing, An Na, and Wang Zhiyong
By adding the nonlinear medium in the cavity, the supercontinuum laser is produced by the resonant cavity directly. The problem of the traditional super continuous spectrum laser source demanding the high power and multi stage amplification structure is avoided. In the cavity, using the acoustic optical modulator (AOM)By adding the nonlinear medium in the cavity, the supercontinuum laser is produced by the resonant cavity directly. The problem of the traditional super continuous spectrum laser source demanding the high power and multi stage amplification structure is avoided. In the cavity, using the acoustic optical modulator (AOM) as the Q medium, the pulse is divided under the influence of the modulation instability, and the supercontinuum laser with average output power of 102 mW is obtained directly, with the corresponding optical-optical efficiency of 5%. In addition, the spectral range is from 440 nm to 1700 nm, with 10 dB flatness of 500 nm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202005 (2016)
Research on Conversion Technology from Non-Polarized to Linearly Polarized Laser Based on the Principle of Polarization Phase Locking
Dong Suhui, Wang Xiaolin, Su Rongtao, Zhou Pu, and Yang Lijia
A novel method to adaptively convert laser beam from non-polarized to linearly polarized based on the principle of polarization phase locking is presented. The non-polarization laser is divided into two beams whose polarization states are perpendicular to each other by a polarization splitter. Based on the principle ofA novel method to adaptively convert laser beam from non-polarized to linearly polarized based on the principle of polarization phase locking is presented. The non-polarization laser is divided into two beams whose polarization states are perpendicular to each other by a polarization splitter. Based on the principle of coherent polarization beam combining, and used the phase modulator whose operating voltage is optimized by parallel gradient descent algorithm to keep the difference of phase of the two splitter beams to mπ. The output beam is linearly polarized laser with high polarization extinction ratio. In theory, the model of adaptive polarization conversion is built, and the factors affecting the efficiency and polarization extinction ratio are analyzed. In experiment, experiment system is built based on the optical path of free- space structure, and the adaptive conversion of non-polarization maintaining laser to a linearly one with the polarization extinction ratio of 93.5% and the converting efficiency of 88% is realized..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202006 (2016)
Quasi-Phase Matching and C erenkov Radiation Harmonics in Nonlinear Photonic Crystals with Fractal Superlattices
Ma Boqin, Tian Shaohua, and Wang Ye
Lithium niobate (LiNbO3) nonlinear photonic crystals with Sierpinski fractal superlattices are fabricated successfully using high voltage electric field, and their quasi-phase matching and C?erenkov radiation harmonics are studied theoretically and experimentally. The relationship between the fundamental wavelengths anLithium niobate (LiNbO3) nonlinear photonic crystals with Sierpinski fractal superlattices are fabricated successfully using high voltage electric field, and their quasi-phase matching and C?erenkov radiation harmonics are studied theoretically and experimentally. The relationship between the fundamental wavelengths and the order of quasi-phase matching harmonics is gotten theoretically. This result corresponds to the experimental value. For one reciprocal vector, quasi-phase matching second-harmonics of 2 kinds of wavelength can be accomplished. The collinear and non-collinear quasi-phase matching second- and third-harmonics in the near infrared wavebands are observed. The distribution of C?erenkov second- and third-harmonic radiation angles as a function of input fundamental wavelength are calculated and the results agree with the experiments. C?erenkov radiation angles reach the minimum at some certain wavelengths. C?erenkov third-harmonic radiation angles are larger than the secondharmonic ones at the same wavelength..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 202007 (2016)
Materials and Thin Films
Shortwave Pass Cutoff Filter of Optical Fiber Community Antenna Television Transmission Systems
Wu Boqi, Dong Lianhe, Sun Yanjun, Leng Yanbing, Wang Li, and Zhang Hengxu
The shortwave-pass cutoff filter (SWPF) can be used into the community antenna television (CATV) to restrain and distinguish diverse signals. It is the important component in the CATV transmission systems. The film is studied in order to reduce the transmission noise and improve the quality of signals. On account of thThe shortwave-pass cutoff filter (SWPF) can be used into the community antenna television (CATV) to restrain and distinguish diverse signals. It is the important component in the CATV transmission systems. The film is studied in order to reduce the transmission noise and improve the quality of signals. On account of the demands for parameters of the cutoff filter during the transmission systems, the suitable material of the thin film is determined. The testing results are gained from the equivalent model of the film. The light-operated tooling values of the coating materials and the thickness of the specifically higher sensitive film are adjusted. Conclusively, the mismatching of the film is removed during the coating process. The SWPF with less layers is fabricated. The reflectance is less than 1% from 1100 nm to 1360 nm, while the transmittance is less than 0.08% at 1490 nm ±20 nm and the transmittance is less than 0.05% at 1550 nm±20 nm. It is found that the film can meet the requirements of CATV transmission systems..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 207001 (2016)
Measurement and Metrology
Three-Dimensional Shape Absolute Measurement Based on Laser Speckles
Zhao Minglu, Ma Xiao, Zhang Zibang, Liang Man, Li Ying, and Zhong Jingang
The longitudinal coherence properties of laser speckles are investigated. The properties are then utilized for three-dimensional (3-D) shape absolute measurement, bringing a feature that phase unwrapping is released. A sequence of speckle images is captured by a CCD camera at different longitudinal positions. The laterThe longitudinal coherence properties of laser speckles are investigated. The properties are then utilized for three-dimensional (3-D) shape absolute measurement, bringing a feature that phase unwrapping is released. A sequence of speckle images is captured by a CCD camera at different longitudinal positions. The lateral displacement of the speckle can be obtained by calculating the correlation among the speckle images. According to the relationship between the longitudinal length and the lateral displacement, the absolute measurement of height from the object surface to reference plane can be realized. Additionally, the phase unwrapping process is released in data processing. A projection-lens system in the technique of projected digital speckle patterns is also released, because the laser speckle field is generated by a laser which illuminates on a frosted glass. The structure of the system is simple and convenient for implement. This technique is potential to be used in practice..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 208001 (2016)
Non-Invasive Investigation of the Microstructure of the Ding Kiln Porcelain with Optical Coherence Tomography
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical coherence tomography (OCT) is a non-destructive subsurface tomography system based on low coherence interferometry. Non-invasive nature and high speed of acquisition of OCT make it possible to image relic and provide subsurface morphology visualization. Porcelain from Ding kiln of Northern Song dynasty is scannOptical coherence tomography (OCT) is a non-destructive subsurface tomography system based on low coherence interferometry. Non-invasive nature and high speed of acquisition of OCT make it possible to image relic and provide subsurface morphology visualization. Porcelain from Ding kiln of Northern Song dynasty is scanned and imaged to visualize the subsurface morphology of the surface glaze and core. Layer structures and interfaces can be visualized clearly from OCT images. The characteristics of the thickness of the glaze layer, bubbles and crystal particles in glaze, the penetration depth of OCT in porcelain are analyzed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 208002 (2016)
Multi-Beams Time-Synchronization Measurement for Intertial Confinement Fusion Laser Facility
Zhang Bo, Peng Zhitao, Lü Jiakun, Sun Zhihong, Dong Jun, and Lu Zongui
A method measuring timing synchronization of multi-beams laser for intertial confinement fusion (ICF) facility is proposed. Firstly, the time interval of reference laser beam arriving criterion point and target point is measured. Secondly, the time interval of reference laser beam arriving criterion point and measured A method measuring timing synchronization of multi-beams laser for intertial confinement fusion (ICF) facility is proposed. Firstly, the time interval of reference laser beam arriving criterion point and target point is measured. Secondly, the time interval of reference laser beam arriving criterion point and measured laser beam arriving target point is measured, the D- value between these two intervals stand for the time synchronization difference between reference beam and measured beam arriving the same target point. The analysis shows that the precision of this method is 25.2 ps.The measurement technology is simple and efficient, and it has been successfully applied in the synchronization measurement of ICF laser facility..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 208003 (2016)
Optical Communication
Laser Performance of Yb3+-Doped Photonic Crystal Fiber Using the Powder Sinter Direction Drawn Rod Technology
Xia Changming, Tian Hongchun, Hou Zhiyun, Liu Jiantao, Zhang Sa, Zhang Wei, Fu Jian, Wu Jiale, and Zhou Guiyao
A kind of Yb3+-doped photonic crystal fiber with small core fabricated using the powder sinter direction drawn rod technology is reported. Using the Yb3+-doped photonic crystal fiber as the laser gain medium, a fiber laser with the central wavelength of 1045 nm is obtained with the excitation of 976 nm by using the lasA kind of Yb3+-doped photonic crystal fiber with small core fabricated using the powder sinter direction drawn rod technology is reported. Using the Yb3+-doped photonic crystal fiber as the laser gain medium, a fiber laser with the central wavelength of 1045 nm is obtained with the excitation of 976 nm by using the laser diode. In addition, the influence of the fiber length on the laser properties of fiber laser is experimentally investigated. The maximum output power is limited to 0.42 W by available small fiber core. The slope efficiency is 33%. The results show that the Yb3+-doped photonic crystal fiber fabricated in the powder sinter direction drawn rod technology can be used as the potential optical material for the high power fiber laser.powder sinter direction drawn rod technology.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 205001 (2016)
Method of Brillouin Scattering Spectrum Character Extraction Based on Genetic Algorithm and Quantum-Behaved Particle Swarm Optimization Hybrid Algorithm
Zhang Yanjun, Xu Jinrui, and Fu Xinghu
A new optimization algorithm is presented, which is based on the genetic algorithm (GA) and quantumbehaved particle swarm optimization (QPSO) algorithm. The algorithm uses the crossover and mutation operators of GA to optimize the QPSO algorithm, improves its global search ability and overcomes the disadvantage that QPA new optimization algorithm is presented, which is based on the genetic algorithm (GA) and quantumbehaved particle swarm optimization (QPSO) algorithm. The algorithm uses the crossover and mutation operators of GA to optimize the QPSO algorithm, improves its global search ability and overcomes the disadvantage that QPSO algorithm easily falls into local extremum. It is used to extract the character of the Pseudo-Voigt-shaped Brillouin scattering spectrum. The parameters estimation and simulation analysis of Brillouin scattering spectrum are analyzed under different weight ratios, line widths and signal-to-noise ratios. The experimental data of Brillouin scattering spectrum are collected in different temperatures and processed by GA-QPSO algorithm.The experimental results show that the GA-QPSO algorithm can improve the frequency shift extraction accuracy of Brillouin scattering spectrum. The maximum error of frequency shift fitting is 2.18 MHz under 25 ℃ and the average fitting error decreases with the increase of temperature, gradually.The frequency shift fitting maximum error is 0.065 MHz under 80 ℃. Therefore, the new algorithm can be used for measuring the temperature and strain in Brillouin scattering sensing system. It has a very good application prospect in improving spatial resolution and detection precision..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 205002 (2016)
Measurement Meathod for Real-Time Transmission of Optical Singal Based on Single Photon Detection
Zhu Bo, Zhu Yong, Lu Lin, Zhang Baofu, Wu Chuanxin, and Wei Yimei
The system of peak time delay tracking is designed, which bases on peak count rate scanning method for single photon detector. By scanning the time range near the previous peak position, a group of data can be compared to find the biggest value for determining the new peak position. It implements the peak of real-time The system of peak time delay tracking is designed, which bases on peak count rate scanning method for single photon detector. By scanning the time range near the previous peak position, a group of data can be compared to find the biggest value for determining the new peak position. It implements the peak of real-time tracking experiment during 125 km optical fiber in the environment of rapidly changing temperature. In order to solve the precision problem which is limited by the long step, the system introduces the polynomial fitting method to increase the accuracy. The accuracy of the light pulse transmission time obtained by peak time delay tracking system is superior to that obtained by avalanche photodiode directly measuring method, which is proved by the comparison experiment of single passing and double passing real-time measurements..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 205003 (2016)
Demodulation Method of Pulse-Wave Sensing by Fiber Bragg Grating Based on Mach-Zehnder Interferometer
Miao Changyun, Shen Ziqi, and Zhang Cheng
A wavelength demodulated method of fiber Bragg grating (FBG) is proposed to measuring pulse signal, which can be applied to smart clothing. Based on the photonic crystal fiber (PCF), a kind of Mach- Zehnder interferometer (In-line MZI) is fabricated on the basis of mode interference. The interferometer works as an edgeA wavelength demodulated method of fiber Bragg grating (FBG) is proposed to measuring pulse signal, which can be applied to smart clothing. Based on the photonic crystal fiber (PCF), a kind of Mach- Zehnder interferometer (In-line MZI) is fabricated on the basis of mode interference. The interferometer works as an edge filter in the wavelength demodulation system of FBG. The temperature sensitivity of the interferometer is lower than 3.5 pm/℃ (range from 25 ℃ to 60 ℃ ). The experiment results indicate that the system can achieve linear demodulation within the range of 2 nm, with a wavelength sensitivity of 0.055 nm-1 and a wavelength resolution of 2.2 pm. The demodulation results of FBG pulse signal measured from the proposed system are consistent with the results measured from SM130 demodulation instrument.crystal fiber.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 205004 (2016)
Beam Steering Performance Simulation of Liquid Crystal Spatial Light Modulator Based on 2D Scalar Diffraction
Ding Ke, and Qi Bo
Liquid crystal spatial light modulator (LCSLM) can be applied to beam steering. Considering that the one-dimensional scalar diffraction analytic method can only solve the diffraction efficiency, two-dimensional scalar diffraction numerical method is introduced and the sampling demand and realization algorithms are striLiquid crystal spatial light modulator (LCSLM) can be applied to beam steering. Considering that the one-dimensional scalar diffraction analytic method can only solve the diffraction efficiency, two-dimensional scalar diffraction numerical method is introduced and the sampling demand and realization algorithms are strictly analyzed. After phase stages and nonlinearity of LCSLM are modeled, the spatial distribution of circular beam through LCSLM and focus lens is calculated, diffraction efficiency and steering accuracy are simulated with variety of parameters. The relations between the stages and accuracy efficiency with different steering angles are concluded, which can provide choosing basis for liquid devices. Using BNS 256×256 liquid device, the beam steering experiment in which the accuracy and efficiency of different steering angles are researched is established and simulations according to experimental parameters are also done. The experimental and simulation results show good agreement, which demonstrates that two-dimensional scalar diffraction can be used for engineering performance evaluation of LCSLM device..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 205005 (2016)
Design of Wide-Angle Laser Beam Splitter with Sub-Wavelength Multi-Level Structure
Chen Qi, Li Guojun, Fang Liang, and Zhou Chongxi
Splitting angle is one of the significant performance parameters of diffractive laser beam splitter. Current study of wide-angle diffractive beam splitter mainly focuses on Dammann grating. Dammann grating relies on its periodic transition points to modulate the incident optical wave, however the inhomogeneity of outgoSplitting angle is one of the significant performance parameters of diffractive laser beam splitter. Current study of wide-angle diffractive beam splitter mainly focuses on Dammann grating. Dammann grating relies on its periodic transition points to modulate the incident optical wave, however the inhomogeneity of outgoing beams is extremely sensitive to the precision of transition points, and the existing processing technology cannot meet the requirement of design accuracy. So, using a sub-wavelength multi-level structure to achieve wide-angle beam splitting is put forward and an actual design example of sub-wavelength 16 levels grating is given, whose incident wavelength is 1.55 μm, beam splitting number is 16 and diffraction angle is 29°. Getting an initial structure by scalar diffraction theory and then applying rigorous coupled- wave analysis and genetic algorithm to do a vector optimization, finally the diffraction efficiency rises to 89%, inhomogeneity drops to 4.53%. The results indicates that sub-wavelength multi-level structure can achieve wide-angle beam splitting with high diffraction efficiency and homogeneity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 205006 (2016)
Optical Design and Fabrication
Two-Stage Static Correction of Aircraft Conformal Window Aberration
Zhao Chunzhu, Cui Qingfeng, Piao Mingxu, and Zhao Lidong
Aircraft conformal windows have asymmetrical shape and usually tilt relative to the imaging system behind. Thus, rotationally symmetrical fixed corrector having the simplest structure can not be applied to aberration correction for aircraft conformal windows. To simplify the structure of aircraft conformal correction sAircraft conformal windows have asymmetrical shape and usually tilt relative to the imaging system behind. Thus, rotationally symmetrical fixed corrector having the simplest structure can not be applied to aberration correction for aircraft conformal windows. To simplify the structure of aircraft conformal correction system to the greatest extent, the two-stage static correction of aircraft conformal window aberration is presented. This solution makes fixed corrector applied to the aberration correction for aircraft conformal windows. The first stage static correction is to correct the asymmetrical aberration introduced by the conformal window at 0° field of regard along the axis based on some static correction method. This stage provides condition for using fixed corrector. It is proved theoretically that the first stage static correction can be achieved by designing the inner surface of the conformal window. The second static correction is to correct the dynamic aberration varying with the look angle introduced by the conformal window using fixed corrector. The two-stage static correction principle of aircraft conformal window aberration is clarified. Based on this principle, a design example is presented..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 216001 (2016)
Remote Sensing and Sensors
Positioning Model and Simulation of Conical Scanning Airborne Laser Bathymetry System
Shen Erhua, Zhang Yongsheng, and Li Kai
Based on the internal structure of the circular scanning airborne laser bathymetry system coastal zone mapping and imaging lidar (CZMIL), the vector equations of laser in the prism, atmosphere and water are deduced and rectified to remove the mounting error of the prism, scanner and laser. With the vector equations andBased on the internal structure of the circular scanning airborne laser bathymetry system coastal zone mapping and imaging lidar (CZMIL), the vector equations of laser in the prism, atmosphere and water are deduced and rectified to remove the mounting error of the prism, scanner and laser. With the vector equations and the attitude and location data provided by global position system/inertial navigation system, the laser point positioning model is deduced in the mapping coordinates. The intersection of laser line and sea surface is simulated depending on the mathematical principles of line and plane intersection. Combined with the direction vector of laser line in the water got by the refraction principle and the sea floor plane mathematical equation, the location of the laser points are simulated. Finally the influences of the plane attitude and height on the point clouds distribution are discussed deeply when the boresight misalignments are existed, which are meaningful to the calibration of system error and the correction of point clouds location for the circular scanning airborne laser bathymetry system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 214001 (2016)
Spectroscopy
Raman Enhancement Study on Au@SiO2 Nanoparticles with Different Au Core Sizes
Yang Jingliang, Li Ruoping, Wang Liwei, Han Junhe, and Huang Mingju
By synthesizing Au@SiO2 nanoparticles with shell thickness of 2~3 nm and core size of 15, 25, 50 nm instead of Au nanoparticles, the relationship between electromagnetic coupling intensity and particle size and gap is studied. The results show that the Au@SiO2 nanoparticles with core size 50 nm have much more enhancemeBy synthesizing Au@SiO2 nanoparticles with shell thickness of 2~3 nm and core size of 15, 25, 50 nm instead of Au nanoparticles, the relationship between electromagnetic coupling intensity and particle size and gap is studied. The results show that the Au@SiO2 nanoparticles with core size 50 nm have much more enhancement. In order to further increase the surface-enhanced Raman scattering (SERS) activity, the Au@SiO2 nanoparticles are layered on the smooth gold surface, and then stronger SERS signal is obtained than that from Au@SiO2 nanoparticles on the silicon surface. The dimensional finite different time domain method is used to simulate the SERS activity under different size, gap and substrate conditions. The results show that the bigger of the particles are and the narrower the gaps are, the higher the electromagnetic coupling intensity of the Au nanoparticles on the smooth gold surface is. It agrees well with our experiment data. In addition, the hot spot from the gap between nanoparticles is transferred to the gap between nanoparticle and substrate. This provides a convenient way to prepare the high sensitivity and stability Raman substrate..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 43, Issue 2, 215001 (2016)
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