Semiconductor Laser Beam Research Articles

Variable magnification beam expander system based on semiconductor laser

Due to the different divergence angles in two perpendicular directions and the presence of astigmatism in edge-emitting semiconductor lasers, the communication distance and efficiency of underwater communication are seriously affected. Therefore, based on the fact that the semiconductor laser beam belongs to Gaussian beam, satisfying Gaussian characteristics and collimating and expanding characteristics, a system composed of fast-axis collimation mirror and variable magnification beam expander is designed. Simulation is performed, and the final divergence angle is calculated. Experimental results show that the divergence angles of the fast axis and the slow axis have been compressed from 49 and 9, respectively, to 0.315 mrad and 0.180 mrad. Simulation demonstrates that the system can achieve propagation over a distance of 100m underwater and solve the alignment difficulty of APT. The designed structure is compact, easy for processing and adjustment, with high practical value, which helps to solve the problems of optical energy loss and low coupling efficiency in underwater long-distance communication.

Review of Developments in Semiconductor Laser Beam Combining Technology

Review of Developments in Semiconductor Laser Beam Combining Technology

Visible laser attenuation characteristics using various polymeric nanocomposites

The attenuation characteristic of a semiconductor laser and green laser beam power with various polymer nanocomposites including PbS, TiO2, V2O5, and CuO are investigated experimentally. Various polymeric nanocomposites with the same concentration of different nanoparticles were prepared using a solution casting technique. The distance between the sample and detector as well as the sample and laser source, and the laser beam incident angle on the surface of the sample are found to be important factors to obtain robust measurements of the attenuation of the semiconductor and green laser beam power. The nanocomposite thin film doped with CuO has more laser beam power attenuation compared to the other prepared nanocomposite thin films. Polymer nanocomposites have various applications, e.g., cut-off laser filters, optical limiting laser, and laser beam power attenuation.

Quantitative Determination of Loss Properties of Semiconductor Laser Beams Propagating in Hollow Waveguides

The loss propertiesof semiconductor laser beams propagating in hollow waveguides (HWGs) are crucial in several applications. The attenuation coefficient of the distributed feedback quantum cascade laser (DFB-QCL) in the HWG was quantitatively determined by measuring its beam profile and laser power along the length of the HWG. The experimental reliability was evaluated, with measurement uncertainties as low as 2.6% and 0.5% for the full width at half maximum (FWHM) of beam profile and the laser power, respectively. We derived an empirical formula for the attenuation coefficient, which is exponential rather than linear with the length of the HWG. The formula was verified to be highly accurate, with a 76.2% reduction in deviation compared to the data in the datasheet. We propose a new concept for a free optical path (FOP) that depends on the inner diameter of the HWG and the incident angle of the beam. The FOP could be an excellent parameter for designing or optimizing HWG-based sensors.

Hydrogen gas detection by Raman Scattering using multiple laser reflection

It is the great interest for detecting hydrogen for safety in the hydrogen society. The sensitivity of detecting hydrogen by Raman scattering was improved about 35 times by using multiple reflections of excite laser beam compared to a single laser beam. 355 nm semiconductor laser beam was reflected about 30 to 40 times between the two concave mirrors. The detection limit of hydrogen was 0.1% and Raman intensity showed linear relation with the hydrogen concentration.

Theoretical and experimental research on crosstalk in spectral beam combining of a laser diode bar with a high fill factor.

Spectral beam combining is an important way to improve the brightness of semiconductor laser beams. For a spectral beam combining system, crosstalk between different emitters would cause the deterioration of beam quality and the reduction of beam combining efficiency, especially for the laser diode bar with a high fill factor. In this paper, an analysis model of the spectral beam combining system with crosstalk is established. The most important advantage of this model is that it can analyze the spectral distribution of the combined beam and also give a relatively good estimation for the beam quality parameters, such as beam size and far-field divergence angle. This model is verified by the experimental results. Furthermore, based on the theoretical model, a method for eliminating crosstalk is developed. By introducing a spatial filter inside the grating external cavity, the crosstalk between different emitters is blocked in the far field, and the beam quality is improved. In the experiment of beam combining of five emitters, after crosstalk is eliminated, the divergence angle of the combined laser beam is reduced from 10.09 to 4.73 mrad, the beam parameter product is reduced from 2.95 to 0.91 mm⋅mrad, and the power of the main lobe is improved from 1.77 to 2 W.

High Power Heating Light Source Based on Semiconductor Laser Beam Combintion Technology

High Power Heating Light Source Based on Semiconductor Laser Beam Combintion Technology

Vein width measurement of groundwater on Earth's surface using Semiconductor Laser Light and Proton Precession Magnetometer

Near-surface geophysical methods such as Semiconductor LASER Light Box (SCLLB) and Proton Precession Magnetometer (PPM) coupled with Vertical Electrical Soundings (VES) and water dowsing approach are used to measure the vein width of Groundwater (GW) on the Earth's surface at fifteen locations in the Deccan Trap flood basalt area in Pune region, Maharashtra, India. The main objective is to validate old simple water dowsing way of GW detection in hard rock using the established modern science and technology namely VES, PPM and SCLLB techniques. On the basis of deflection of the L-shaped copper rods, the presence of GW with clues on the edges of GW vein is detected using the old traditional dowsing method. The efficacy of dowsing is verified by VES. It is found that apparent resistivity in the range from 48Ωm to 117Ωm over the GW location delineated by the dowser is relatively low, thus confirming the presence of GW in the study area. Variation in the intensity of Earth's Magnetic Field (EMF) measured by PPM is found in the range from 37,788nT to 43,242nT over GW locations. High magnetic intensity values indicated high GW potential in weathered vesicular-amygdaloidal basalt and magnetic field gradient changes enabled to calculate GW vein width. It is suggested that water dowsers might get a dowsing reaction as a result of entering into magnetic field gradient changes caused by GW. Digital barometer records the atmospheric pressure (P) and temperature (T) showing that both P and T are higher than the non-GW location which alters refractive index (RI) of medium over GW locations in the study area. A small change in RI alters the intensity of the semiconductor laser beam (≈234 μA to 1204 μA) indicating the edges of GW vein, thus giving the width of the vein. The results obtained by PPM and SCLLB match with dowsing responses. It is found that GW sources and width of GW vein (≈1 m to 6 m) in Deccan basaltic terrain can be measured quickly and with ease by using SCLLB in comparison to VES and PPM. It is concluded that the application of proposed modern instrumental measurement survey by PPM and SCLLB coupled with the old simple technology of water dowsing demonstrated the potential to generate a subsurface water resource database at the national level, especially in hard rock.

Advances in high power high beam quality diode lasers

Semiconductor laser enjoys its benefits such as small volume, light weight, long operation life, various selectable wavelength and direct current driving, meanwhile suffers from its beam quality which is making it hard for direct applicdations. Researchers around the world realize that it is beam quality has the same importance as power, and acquiring high power and high beam quality is the key issue in semiconductor laser induxtry. The question of how to improve the beam quality of high power semiconductor lasers is attracting increasing attention from researchers home and abroad. Considering the application fields which require high power high beam quality, such as industry processing and national defense, this paper discussed the research progress on both diode laser unit devices and laser beam combining sources. First of all, the relationships between single laser emitter′s structureand themodeof laser units, including lateral mode, transverse mode and longitudinal mode, are analyzed. Lateral mode is the main factor which limits the high beam quality for high power semiconductor lasers. Ridge waveguide is the main method adopted to realize single lateral mode. A method called longitudinal photonic bandgap crystal is introduced to manipulate the transverse mode of a single laser unit, which can acquire large optical near field and high beam quality even in high current input. To control longitude mode, usually to acquire single longitude mode in single semiconductor laser unit, distribute Bragg reflectors and distribute feedback structures using gratings in fabrication is also introduced in this section. And then we summarize the methods and some results of controlling modeusedinternationalresearchers. Further more, we introduced the lasers beam technology, including beam shaping and beam combining, considering all conditions of single emitters beam combining, mini bar beam combining, centimeter bar beam combining, laser stacks beam combining and laser systems beam combining. In beam combining technology, we introducted the method of traditional beam combining, including polarizetion beam combining and wavelength beam combining. Then the method of using dense wavelength division multiplexing with volume Bragg gratings to realize beam combinign is also introduced. Spectrum beam combining method using a Bragg diffractive grating is then introduced, which may realize a high beam quality of a single emitter′s beam spot with a laser bar′s optical power. Furthermore, coherent beam combining considering each laser unit′s wavelength, polarization and phase to realize high power high intensity farfield is also introduce. Then, the lastest international reported of high power, high beam quality diode laser combining sources are introduced, and characteristics of laser beam technology and development trends arediscussed and analyzed. Finally, the developments of high power high beam quality diode lasers are prospected. Right now, our country still have a distance below internal research in high quality semiconductor laser chip and beam combining source. The semiconductor laser chips′ power and beam quality needed to be improved. The technology of 10 kW level beam combining and optical fiber coupling technology is still urged to be acquired. Grating fabrication in optical beam combining technology and chip fabrication are also needed to be conquered.

Experimental and theoretical study of the heating dynamics of carbon-containing optothermal fibre converters for laser surgery

We have studied carbon-containing optothermal fibre converters (COTFCs) that are located on the distal end of a quartz – quartz optical fibre for delivering laser radiation in medical laser surgery systems and differ in the thickness and structure of the layer of a material converting laser radiation into heat. The heating dynamics of ‘thin-film’ and ‘3D’ converters have been investigated at average incident semiconductor laser beam powers of 0.3, 1.0 and , with the converters placed freely in air. The results demonstrate that, before the instant of disintegration, the efficiency of laser heating of the converter surface can reach for thin-film converters, for spherical 3D converters and for planar 3D converters. The thin-film converter breaks down at an average laser beam power as low as , which is accompanied by a considerable reduction in heating efficiency and is caused by the disintegration of the carbon film on its surface. The spherical 3D converter breaks down at an average power of , as a result of the disintegration of the carbon film on its surface and partial melting of a modified layer containing microbubbles. The carbon film on the surface of the planar 3D converter also disintegrates at an average power of , but the structure of the modified layer remains unchanged. We have constructed structural and optophysical models of the converters by simulating light absorption in carbon films on the surface of the COTFC and inside the microbubbles present in the modified layer of the converters. The proposed models of the COTFCs have been shown to adequately describe real converters.

608 消費電力最小化原理に基づくレーザによる薄板のひずみレス全体焼入れ(OS3 先進製造技術(4),研究討論セッション)

We focus on a small power semiconductor laser beam as a heat source to perform less deformation entire hardening of thin plate. In the present report, we discuss the plate deformation and the power consumption in laser processing. As a result, a suitable laser irradiating condition is found to minimize the power consumption under the less plate deformation

Semiconductor laser beam bending

This study is about a single-component cylindrical structured lens with a gradient curve that was used for bending laser beams. It operates under atmospheric conditions and bends the laser beam independently of temperature, pressure, polarity, polarization, magnetic field, electric field, radioactivity, and gravity. A single-piece cylindrical lens that can bend laser beams was developed. Lenses are made of transparent, tinted, or colored glass and are used to undermine or absorb the energy of laser beams. This study is not a work of a plasma filamentation, nor is related to a self-accelerating wave packet. Rather, it focuses on bending the laser beam as required. The dimensions of the light-bending curvatures vary depending on the source and the lens. This is an application of laser beam bending. The dimensions of the captured images are 500 $\times $ 700 mm.

The Influence of Laser Beam and Auxins on Rooting of Leatherleaf Viburnum (VIBURNUM RHYTIDOPHYIIUM Hemsl.) Cuttings

Abstract The aim of this work is to compare the effect of three- and sixfold irradiation with a semiconductor laser beams of 200 mW power and wavelength equal to 670 nm and the rooting agent on the percentage and quality of rooted cuttings of leatherleaf viburnum. The most effective for root number and root length was threefold irradiation and for fresh root weight threefold irradiation applied together with the rooting agent.

Optimum design of aspheric collimation lenses for optical antenna system

Three kinds of aspheric collimation lenses for optical antenna have been design by optimization. The aspheric cylinder collimation lenses with aspheric surfaces (such as elliptic, hyperbolic and parabolic marginal profiles) have been researched for the semiconductor laser beam with the characteristic of dot emitting source. Based on genetic algorithm and the optimization toolbox of MTLAB, the divergence angle has been optimized. The collimation divergence angle is less than 115μrad has been measured by laser beam analyzer. This optimum design laser beam collimation lenses as a pre-collimation system can be used for optical antenna system. And it can be widely used in modern space laser communication.

Quantitative Analysis of Uranium in Aqueous Solutions Using a Semiconductor Laser-Based Spectroscopic Method

A simple analytical method based on the simultaneous measurement of the luminescence of hexavalent uranium ions (U(VI)) and the Raman scattering of water, was investigated for determining the concentration of U(VI) in aqueous solutions. Both spectra were measured using a cw semiconductor laser beam at a center wavelength of 405 nm. The empirical calibration curve for the quantitative analysis of U(VI) was obtained by measuring the ratio of the luminescence intensity of U(VI) at 519 nm to the Raman scattering intensity of water at 469 nm. The limit of detection (LOD) in the parts per billion range and a dynamic range from the LOD up to several hundred parts per million were achieved. The concentration of uranium in groundwater determined by this method is in good agreement with the results determined by kinetic phosphorescence analysis and inductively coupled plasma mass spectrometry.

Laser beam shaping with an ellipsoidal lens

This paper presents a semiconductor laser beam shaping system that can collimate the irradiance profile effectively by using an ellipsoidal lens. Geometrical optics analysis based on the ray tracing method is done and the formulas to calculate the shape of ellipsoidal lens are given. Both the theoretical and experimental result show that the laser beam system works effectively; the divergence angle is reduced to less than 1° in the fast-axial direction. By using epoxy resin, this shaper collimates a semiconductor laser beam and packages the laser diode (LD) at the same time, which simplifies the manufacturing process and greatly reduces the LD volume. Because of the small volume, low-cost, high rigidity and easy fabrication, the shaper is of great value in the field of semiconductor laser diode applications.

Dynamic simulation on the temperature field of laser micro-patterning metal in the liquid

To further understand the mechanism of laser electrochemical etching metal, it is necessary to describe the temperature field induced by laser heating metal at the liquid–solid interfaces. For solving the complex problem of laser heating a metal immersed in a liquid, the thermal phenomena adjacent to the metal–liquid interface, which was induced by means of irradiating a stainless steel sample immersed in a liquid with an 808nm semiconductor laser beam, were numerically investigated. Based on a simplified method to solve the transient explosive boiling when a continuous wave (CW) laser heating a material in a liquid, a commercial finite element analysis (FEA) code (ABAQUS) was used to directly solve and model the transient temperature fields of laser micro-patterning metal in a liquid. As known from simulation results, the simulation of laser scanning indicates that it realizes the effect of pulse laser heating owing to laser moving and liquid cooling. Moreover, laser scanning achieves the pattern at a high resolution. At the same time, the experiment phenomena also proved that the simulation results were reasonable.

The effect of pressure on GRIN lenses

The changes of the optical power of Gradient Index (GRIN) lenses occurring in hydrostatic pressures of the range of 0–2 GPa are investigated. The measurements of the position of the waist of the semiconductor laser beam revealed the increase of the optical power of the lenses with increasing pressure. The use of the special plano-concave lenses insensitive to the changes of the refractive index of the pressure medium allowed to attribute the changes to the increasing index gradient in GRIN material. The effect has been explained within the frame of Mueller’s theory of photoelasticity. The findings have been then confirmed in experiments with the plano-planar and plano-convex lenses of the same materials.

Optical Antenna System Design for 3D Imaging Lidar

A new aspheric surface pre-collimation lenses system for the optical antenna of threedimensional (3D) imaging of lidar has been optimally designed and simulated by optical design software CODE-V. Four kinds of aspheric surfaces spherical lenses including the sections of spherical, elliptical, hyperbola, and parabola have been researched. The optical system, including the elliptical cylinder lenses collimation and the optical antenna, can be realized less than 5 rad collimation angle for dot source semiconductor laser beam.

Development of a novel two‐laser beam stereolithography system

PurposeThe purpose of this paper is to develop a novel two‐laser beam stereolithography system which has the advantages of low cost, fabrication time reduction and high accuracy.Design/methodology/approachThe wavelengths of the two semiconductor laser beams are determined to be 405 nm (blue light) and 532 nm (green light), respectively, according to the relative absorbance rate of the visible‐light curable resin (NAF202) used. The blue light laser is suitable for scanning the contour of objects because of its fast absorbance, thus giving a narrow cured depth. The green light laser is better suited to scanning the internal crosshatch to condense the fabrication time because of its deep penetration and its high power results in a wide cured width. A photoabsorber, carbon powder with an average diameter of 0.1 μm, is adopted to control the cured layer thickness. An adaptive crosshatch technique is introduced and applied to the fabrication process. Two benchmarks are proposed and fabricated using the developed system to evaluate the fabrication capability. Furthermore, a coordinate measuring machine is employed to evaluate the accuracy of the fabricated benchmark parts.FindingsAn optimal weight percentage of 1.5 is specified. The technique developed in this study is feasible for the fabrication of highly‐convoluted objects such as fan blades. The inclusion of the adaptive crosshatch technique in the developed system significantly reduces the fabrication time.Originality/valueThe results presented in this paper show that the developed system can fabricate objects quickly with high accuracy.