This PDF file contains the front matter associated with SPIE Proceedings Volume 9294, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

One provides a simple recipe, which is manipulating refractive of doped region of the MCPCF, to obtain the equal amplitude distribution of the in-phase supermode for multicores photonic crystal fibers (MCPCFs). Using coupled mode theory and vector finite element method (VFEM), a 7-core PCF is analyzed in detail and the results are applied to 16-,18- and 19-core PCFs, which will find important applications in high-power MCPCF lasers and amplifiers. One shows that it is possible to construct uniformly distributed modes for the nontrivial examples of 7- 16-, 18- and 19-core PCFs. One demonstrates that an equal amplitude distribution of in-phase supermode can be achieved by manipulating refractive of doped region in cores area. This research would provide a theoretical basis for investigating equal amplitude in-phase supermode in the MCPCF.

Micro unmanned aerial vehicle, mostly powered by electricity, plays an important role in many military and civil applications, e.g. military detection, communication relay et al. But restricted endurance ability severely limits its applications. To solve the problem, laser wireless power transmission system is proposed. However, overall efficiency of the system is quite low. This paper describes basic structure of laser wireless power transmission system and its working process. The system consists of two major modules: a high power laser source transmitting energy and a photovoltaic receiver converting optical energy into electricity. Then factors influencing efficiency of the system are analyzed. It suggests that electro-optical efficiency of laser, atmospheric impact on laser beam and photo-electric efficiency of photovoltaic receiver play significant role in overall efficiency of the system. Atmospheric impact on laser beam mostly derived from refraction, absorption, scattering and turbulence effects, leads to drop in energy and quality of laser beam. Efficiency of photovoltaic receiver is affected by photovoltaic materials. In addition, matching degree between intensity distribution of laser beam and layout of photovoltaic receiver also obviously influence efficiency of photovoltaic receiver. Experiment results suggest that under non-uniform laser beam illumination, efficiency of photovoltaic receiver mostly depends on layout of photovoltaic receiver. Through optimizing the layout of photovoltaic receiver based on intensity distribution of laser beam, output power is significantly improved. The analysis may help to take corresponding measures to alleviate negative effects of these factors and improve performance of laser wireless power transmission system.

A tunable multi-wavelength Brillouin fiber laser with double Brillouin frequency spacing based on a four-port circulator is experimentally demonstrated. The fiber laser configuration formed by four-port circulator isolates the odd-order Brillouin stokes signal to circulate within the cavity only. In addition, it also allows propagation of the incoming Brillouin pump and even-order Stokes signals from four-port circulator to output coupler .A L-band erbiumdoped fiber (EDF) with 1480nm pump is used to amplify Stokes signals and to get more output channels. At the Brillouin pump power of 8dBm and the 1480 nm pump power of 200mw, 5 output channels with double Brillouin frequency spacing and tuning range of 20 nm from 1568nm to 1588nm are achieved.

The paper study on the effect of index distribution on the mode field and calculated the mode distribution in various index profiles. A single mode gaussian hybrid multicore fiber with 19 hexagonally arranged high index quartz rods is designed and investigated. Theoretical and simulative results are presented and compared to the conventional large mode area double clad fiber, the fundamental mode (FM) area can be reached 694.28 μm², the confinement loss of FM and high order modes (HOMs) are 0.186 dB/m and 1.48 dB/m respectively with the bending radius of 20 cm at 1.064 μm wavelength, moreover, the index distribution can resistant the mode field distortion, which caused by fiber bending. So the FM delivery can be formed and the beam quality can be improved.

A new method that adopt fiber laser phase array source to form all optics network in the deep space communication was proposed in this paper. The far-field light intensity figure of 1.55μm fiber laser phase array source was simulated, and the scanning range with changing among array components the phase was obtained. The number of array components was 3×3, wavelength was 1.55πm, and core radius was 10μm. The scanning range was ± 0.9909° when the distance of array components was 80μm. It was found that applying fiber laser phase array source can achieve scanning advantages with dynamic range in the all optics network.

A dual-wavelength linear cavity erbium-doped fiber (EDF) laser based on a fiber grating pair is demonstrated experimentally. A circulator, a 980nm/1550nm wavelength division multiplexing (WDM) coupler, a 1×2 coupler, a polarization controller, a 6m long erbium-doped fiber and a fiber grating pair for wavelength interval of 0.3nm are included in the structure. A circulator connected at two ports as reflecting mirror structure. A 980nm pump source pump an erbium-doped fiber with a length of 6m consist of an erbium doped fiber amplifier. Through adjusting the state of the polarization controller, the transmission characteristic of cavity is changed. In both polarization and wavelength, the feedback from the fiber grating pair results in the laser operating on two longitudinal modes that are separated. The birefringence induced by the fiber grating pair is beneficial to diversify the polarization states of different wavelength in the erbium-doped fiber. So it is enhanced the polarization hole burning effect. This polarization hole burning effect greatly reduced the wavelength competition. Then, it was possible to achieve stable dual-wavelength. It turns out the structure generated the stable dual-wavelength with the 0.3nm wavelength interval and the output power is 0.13dBm in the end. The whole system have a simple and compact structure, it can work stably and laid a foundation for microwave/millimeter wave generator. It has a good application performance in the future for scientific research and daily life.

A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier（EDFA） consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.

On the basis of Coherent Beam Combination(CBC) based on Array of Liquid Crystal Optical Phased Arrays(LCOPA array), two major contributions are made in this article. Firstly, grating lobes and side lobes of combined beam are analyzed. Furthermore, according to interference theory the methods to suppress grating lobes and side lobes are put forward. Secondly, a new beam quality factor Q(θ₀) is proposed to evaluate the beam quality of combined beam and several influence factors are discussed. These analysis results help to obtain combined beam with better beam quality.

Structures which are similar to double wedges usually exist in a supersonic inlet. When a supersonic flow goes through double wedges, oblique shock waves intersect and shock wave reflection appears. In an off design condition, Mach Reflection (MR), one kind of shock wave reflection, probably appears. The laser energy deposition helps decrease the Mach stem height and reduce the total pressure loss. Numerical simulation on the influence of deposition location and laser energy in reducing the Mach stem height was investigated in Mach 3.45, 5, 6, 7. Mach Reflection was achieved at different Mach number. The simulations and analysis showed that proper increase of distance between energy deposition location and Mach stem where was near by the upstream oblique shock waves would have a better effect on decreasing Mach stem height. When inflow Mach number changed, the influence of laser energy deposition became different at a variety of deposition location

In this paper, a segment of thulium-doped fiber is pumped by a 976nm laser diode.Broadband gain at centerwavelength of 1953nm is achieved. The maximum amplified spontaneous emission bandwidth is 8nm. Simultaneously, self- oscillation of wavelength spacing 0.073nm is observed. The output power and self- oscillation modes increase with pump power increasing and wavelength spacing of self-oscillation is unchanged.The relation between fiber length and output power at pump power 400mW is analyzed. Higher output power can be abtained by selecting a appropriate fiber length when pump power is unchanged. Through the experiment, a weak absorption band of thulium-doped fiber near 976nm is verified. The structure can be used as narrow linewidth broadband source near 1950nm with the characteristic of low cost, simple structure and good stability.

The soft-killing laser weapon plays an important role in photoelectric defense technology. It can be used for photoelectric detection, search, blinding of photoelectric sensor and other devices on fire control and guidance devices, therefore it draws more and more attentions by many scholars. High power fiber-optic laser has many virtues such as small volume, simple structure, nimble handling, high efficiency, qualified light beam, easy thermal management, leading to blinding. Consequently, it may be used as the key device of soft-killing laser weapon. The present study introduced the development of high power fiber–optic laser and its main features. Meanwhile the key technology of large mode area (LMA) optical fiber design, the beam combination technology, double-clad fiber technology and pumping optical coupling technology was stated. The present study is aimed to design high doping LMA fiber, ensure single mode output by increasing core diameter and decrease NA. By means of reducing the spontaneous emission particle absorbed by fiber core and Increasing the power density in the optical fiber, the threshold power of nonlinear effect can increase, and the power of single fiber will be improved. Meantime, high power will be obtained by the beam combination technology. Application prospect of high power fiber laser in photoelectric defense technology was also set forth. Lastly, the present study explored the advantages of high power fiber laser in photoelectric defense technology.

A narrow-linewidth ytterbium (Yb)-doped phosphate fiber laser based on fiber Bragg grating (FBG) operating around 980 nm is reported. Two different kinds of cavity are applied to obtain the 980 nm narrow-linewidth output. One kind of the cavity consists of a 0.35 nm broadband lindwidth high-reflection FBG and the Yb-doped phosphate fiber end with 0° angle, which generates a maximum output power of 25 mW. The other kind of resonator is composed of a single mode Yb-doped phosphate fiber and a pair of FBGs. Over 10.7 mW stable continuous wave are obtained with two longitudinal modes at 980 nm. We have given a detailed analysis and discussion for the results.

Beam combining (BC) of fiber lasers based on master oscillator power amplifier (MOPA) configuration has been considered as a promising way to achieve high power laser output. In recent years, it has been demonstrated that tip-tilt phase errors impact the combining effect seriously, especially the beam quality in coherent beam combining even if all the beamlets are phase-locked. Adaptive fiber-optics collimator (AFOC) is an effective way to compensate the tip-tilt aberrations in fiber laser systems. As the piezoelectric bimorph actuators used in the AFOCs of traditional type provide very weak force (0.1~1N level), they can only actuate the naked fiber. So the application of traditional AFOCs in high power level is limited by the structure. When the output power is scaled up-to several kW, a coreless end cap is usually spliced on the output side as the end of fiber. Because of the end cap, the expansion of the beam reduces the extractable fluence and avoids fiber facet damage. Then the AFOCs that can be used in high-power situations become the direction of research and development. In this paper, a new structure of AFOC based on flexible hinges is presented for the first time to our knowledge. It utilizes two piezoelectric stacks actuators for X-Y displacement of the fiber end cap placed in the focal planes of the collimating lens. Also the new type of AFOC based on flexible hinges has been developed and demonstrated experimentally. The thrust of zero displacement of the piezoelectric stacks actuators is 330 N. The maximum tip/tilt deviation angle of the collimated beam is 180μrad in X direction and 150 μrad in Y direction for a chosen focal length of 0.05m. The first resonance-frequency of this device is about 700 Hz and the bandwidth of this device is 500Hz. This work provides a reference for beam combing and beam pointing controlling in high power conditions.

Pumping coupler technology is one of the critical technologies for high power laser and amplifier. Side-pumping technology can couple pumping beam into inner cladding of the double-clad fiber through the side of the fiber. Compared to the end-pumping technology by tapered fused bundle (TFB), it has many superiorities. That the signal fiber was not disconnected guarantees high transmission efficiency, providing the possibility of transmitting a high power signal. Additionally, the pump light is coupled into the double-cladding fiber all along the coupler’s body (~5-10 cm long), which reduces the thermal effects caused by leakage of pumping light, resulting in high pump power handling capabilities. For the realization of reliable, rugged and efficient high power fiber amplifiers and fiber laser systems, a novel kind of fused side-pumping coupler based on twisting is developed. The complete simulations were carried out for the process of side-pumping. From detailed information about simulations, we found that the pump efficiencies, one of the vital parameters of pumping coupler, have a significant influence with coupling length, the numerical aperture (NA) and taper ratio of pump fiber. However, the diversification of the parameters drops the high transmission efficiency barely. Optimized the parameters in the simulations, the pump and signal coupling efficiencies are 97.3% and 99.4%, respectively. Based on theoretical analysis, the side-pumping coupler was demonstrated at the pump and signal coupling efficiencies are 91.2% and 98.4%, respectively. This fiber coupler can be implemented in almost any fiber laser or amplifier architecture.

Low-temperature sealing glass (320-380°C) can be applied to the hermetic package of optical fiber devices, without the need of metallization. This paper introduced a PbO-ZnO-B₂O₃-F system low-temperature glass composite which has an softening point as low as 246°C and expansion coefficient of 8.0 ppm/°C. The glass composite was sealed with quartz glass fibers at 360-390°C, then the effect of sintering temperature and holding time on the surface reaction were well investigated. Although the mismatch of expansion coefficient exists within glass fiber, negative expansion filler and parent glass, they combined well with each other after a short time heating. The F- in glass network helped to lower the sealing temperature, wet the oxide surface and promote the combination of parent glass and fibers. The sealing temperature and holding time affect the interface layer and the shape of the fiber. The optimum packaging process should be sealing composite glass and fibers beneath 380°C with shortened holding time as possible. Using glazed glass composite preforms, sealing fiber in a ferrule to achieve compressed package will be helpful to realize hermetic package for optical fiber devices.

Striation-free laser cutting of thick section stainless steel is hard to obtain due to several factors, such as nozzle standoff distance, cutting speed, focal plane position, gas pressure, thickness of metal and recast layer. It will be vital to properly combine these factors in striation-free cutting because striation formation is a complicated process. Therefore, many scholars have been studying the mechanisms of striation formation, which will be systematically summarized in this paper. Based on the review, the author holds that supersonic gas nozzle designing plays a key role in creating an ideal cutting condition. Based on the introduction of some structures of supersonic gas nozzle, this paper proposes that two objectives should be fulfilled in order to achieve striation-free cutting: One is to produce a uniform flow of assistant gas and the other is to get a stable laser cutting temperature field.

With the development of laser transmission technology, the laser ranging and communication technology integration, miniaturization has become an important research direction nowadays. Based on laser ranging and communication integration of the requirements, design the1064nm fiber laser system, to suffice laser communication, laser ranging and beacon beam of the requirements at the same time could be provide the coherent detection to signal beam. The simulation experiment the 1064nm of free space optical communication in the laboratory, the coherent detection sensitivity is higher than -22dBm, the bit error rate 10⁻⁷ laser communication system. Multiple laser ranging to build coherent beam experimental realization of the coupling efficiency is higher than 70%, the laser output power of greater than 21W. The light source system is designed in this paper can realize the previous several lasers to complete the task, not only has the advantage of integration and miniaturization, through the simulation experiment could satisfy the communication requirements of power laser ranging ,and it is ideal light for laser transmission integration technology.

A simulation platform is set up to study the ship-borne laser communications. A liquid crystal spatial light modulator is used as a non-mechanical beam steering control device to simulate beam motions of moving platforms. Because of its light weight, low power and compact form, the liquid crystal spatial light modulator is superior to its mechanical counterparts. The theory of beam steering is introduced firstly. And then the performance of the simulation platform is researched and evaluated. The steering angles range from -2.89° to 2.89° with the control precision of ~ 0.02°. The simulated sinusoidal frequency of the spatial light modulator can reach 4 Hz in maximum. Finally, the beam motions of the ship platforms with different natural rolling periods are simulated based on the platform. The correlation coefficients between the theoretical and the simulated motion curves are greater than 0.9805. Results show that it is feasible to realize the beam motions simulation of specific moving platforms using the liquid crystal spatial light modulator.

Lasers at 2.79 μm emitted by Er:YSGG crystal have attracted considerable interest in biological and medical applications. However, due to the thermal effect of laser crystal, the output power has been limited. In this paper, the advantages of Er:YSGG/YSGG composite crystal in reducing thermal effects and achieving high output power are investigated theoretically and experimentally. The numerical results show that the temperature rising and total thermal deformation of Er:YSGG/YSGG composite crystal are evidently reduced because the undoped YSGG absorbs the heat generated from the Er:YSGG. The maximum temperature rising reduces with increasing of the length of undoped YSGG crystal, and its location moves from the pump face to the inside of the Er:YSGG. The optical path difference of the Er:YSGG/YSGG composite crystal is obviously reduced comparing with that of Er:YSGG crystal, which indicates the thermal focal length of the Er:YSGG/YSGG composite crystal is increased, and the thermal effects are reduced. In experiments, the maximum continuous wave output power of 900 mW with slope efficiency of 12.1% at wavelength of 2.79 μm is obtained in laser diode end pumped Er:YSGG/YSGG crystal. To our knowledge, the output power of Er:YSGG/YSGG crystal is the highest value for the laser diode end pumped Er:YSGG crystal. The thermal focal length of the Er:YSGG/YSGG measured in experiment is increased comparing with that of Er:YSGG. Investigations have demonstrated that the Er:YSGG/YSGG composite crystal has a great advantage in reducing the influence of thermal effects and achieving high output power.

High energy laser weapons are ready for some of today’s most challenging military applications. Based on the analysis of the main tactical/technical index and combating process of high energy laser weapon, a performance calculation and simulation system of high energy laser weapon was established. Firstly, the index decomposition and workflow of high energy laser weapon was proposed. The entire system was composed of six parts, including classical target, platform of laser weapon, detect sensor, tracking and pointing control, laser atmosphere propagation and damage assessment module. Then, the index calculation modules were designed. Finally, anti-missile interception simulation was performed. The system can provide reference and basis for the analysis and evaluation of high energy laser weapon efficiency.

First principles calculations based on the plane wave pseudo-potential method have been carried out to study effects of intrinsic point effects in GaAs saturable absorbers on the related electronic structures and optical properties. The defect energy levels corresponding to each kind of the intrinsic point defect and their electron occupancy are analyzed from the aspects of band structure and partial density of states (PDOS). Furthermore, the impacts on the optical properties of GaAs saturable absorbers made by the native point defects are also obtained. It can be found that the absorption edges of the GaAs with V_Ga defect, V_As defect or Ga_As defect exhibit substantial redshifts, which is mainly attributed to the defect energy levels in the band gap, and the absorption coefficient of the GaAs crystal with V_Ga defect, V_As defect or Ga_As defect is bigger than those with other defects in near-infrared range. The dielectric function and the refractive index of GaAs crystal with V_Ga defect, V_As defect or GaAs defect show redshifts in near-infrared region too. The analysis of the optical properties of GaAs crystal with intrinsic point defects will be helpful in guiding the application of the GaAs crystal as saturable absorber in solid-state laser.

We demonstrate the design and performance of an optical switch that has been constructed for the SG-II upgrading facility. The device is a longitudinal, potassium di-hydrogen phosphate (KDP), 360 mm×360 mm aperture, and 2×1 array electro-optical switch driven by a 20 kV output switching-voltage pulse generator through two plasma electrodes produced at the rise edge of the switching-voltage pulse. The results show that the temporal responses and the spatial performance of the optical switch fulfill the operation requirements of the SG-II upgrading facility.

To theoretically study the feasibility of antifreeze coolants applied as cooling fluids for high power LD heat sink, detailed Computational Fluid Dynamics (CFD) analysis of liquid cooled micro-channels heat sinks is presented. The performance operated with antifreeze coolant (ethylene glycol aqueous solution) compared with pure water are numerical calculated for the heat sinks with the same micro-channels structures. The maximum thermal resistance, total pressure loss (flow resistance), thermal resistance vs. flow-rate, and pressure loss vs. flow-rate etc. characteristics are numerical calculated. The results indicate that the type and temperature of coolants plays an important role on the performance of heat sinks. The whole thermal resistance and pressure loss of heat sinks increase significantly with antifreeze coolants compared with pure water mainly due to its relatively lower thermal conductivity and higher fluid viscosity. The thermal resistance and pressure loss are functions of the flow rate and operation temperature. Increasing of the coolant flow rate can reduce the thermal resistance of heat sinks; meanwhile increase the pressure loss significantly. The thermal resistance tends to a limit with increasing flow rate, while the pressure loss tends to increase exponentially with increasing flow rate. Low operation temperature chiefly increases the pressure loss rather than thermal resistance due to the remarkable increasing of fluid viscosity. The actual working point of the cooling circulation system can be determined on the basis of the pressure drop vs. flow rate curve for the micro-channel heat sink and that for the circulation system. In the same system, if the type or/and temperature of the coolant is changed, the working point is accordingly influenced, that is, working flow rate and pressure is changed simultaneously, due to which the heat sink performance is influenced. According to the numerical simulation results, if ethylene glycol aqueous solution is applied instead of pure water as the coolant under the same or a higher working temperature, the available output of optical power will decrease due to the worse heat sink performance; if applied under a lower working temperature(0 °C, －20 °C), although the heat sink performance become worse, however the temperature difference of heat transfer rises more significantly, the available output of optical power will increase on the contrary.

In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m², and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.

266nm UV laser has a wide range of applications in many fields, such as laser medical treatment, laser processing, precision measure and other applications for the reason of its advantages in wavelength, small diffraction effects, high single-photon energy, and high resolution and so on. BBO crystals absorb parts of the fundamental laser energy and second harmonic laser energy are unavoidable, and thus the temperature raise, so that the existing crystal phase matching conditions change, resulting in phase mismatching in the high-power frequency doubling, greatly influence the 266nm UV laser conversion efficiency. To further study the effect of phase mismatching to conversion efficiency, and improve the conversion efficiency, output power and other output characteristics of 266nm laser, the article mainly describe from the following three aspects. Firstly, took the use of three-dimensional nonlinear crystal temperature distribution which is obtained, the process of BBO crystal thermal-induced phase mismatching is analyzed. Secondly, based on frequency doubling theory, the effects of the thermal-induced phase mismatching affected of conversion in crystals are analyzed. Combining with the phase mismatching of the three-dimensional distributions, the fourth harmonic conversion efficiency with thermal phase mismatching changes of BBO 266nm UV laser are simulated for the first time. Thirdly, by using MATLAB software, the effects of phase mismatching to conversion efficiency in crystal for different waist radius, 532nm laser power and the fundamental beam quality are simulated. The results indicate a good physical interpretation of reasons of high power laser frequency doubling system. It shows that the model established explains the reason of the reduction of conversion efficiency, output power and the beam quality excellently. All results make a leading sense to the research on the compensating of the phase mismatching and on the improvement of conversion efficiency.

The laser transmission characteristics affected in the complex channel environment, which limits the performance of laser equipment and engineering application severely. The article aim at the influence of laser transmission in atmospheric and seawater channels, summarizes the foreign researching work of the simulation and comprehensive test regarding to the laser transmission characteristics in complex environment. And researched the theory of atmospheric turbulence effect, water attenuation features, and put forward the corresponding theoretical model. And researched the simulate technology of atmospheric channel and sea water channel, put forward the analog device plan, adopt the similar theory of flowing to simulate the atmosphere turbulence .When the flowing has the same condition of geometric limits including the same Reynolds, they must be similar to each other in the motivation despite of the difference in the size, speed, and intrinsic quality. On this basis, set up a device for complex channel simulation and comprehensive testing, the overall design of the structure of the device, Hot and Cold Air Convection Simulation of Atmospheric Turbulence, mainly consists of cell body, heating systems, cooling systems, automatic control system. he simulator provides platform and method for the basic research of laser transmission characteristics in the domestic.

The laser detection and identification is based on the method of using laser as the source of signal to scan the surface of ocean. If the laser detection equipment finds out the target, it will immediately reflect the returning signal, and then through receiving and disposing the returning signal by the receiving system, to realize the function of detection and identification. Two mediums channels should be though in the process of laser detection transmission, which are the atmosphere and the seawater. The energy loss in the process of water transport, mainly considering the surface reflection and scattering attenuation and internal attenuation factors such as seawater. The energy consumption though atmospheric transmission, mainly considering the absorption of atmospheric and the attenuation causing by scattering, the energy consumption though seawater transmission, mainly considering the element such as surface reflection, the attenuation of scattering and internal attenuation of seawater. On the basis of the analysis and research, through the mode of establishment of atmospheric scattering, the model of sea surface reflection and the model of internal attenuation of seawater, determine the power dissipation of emitting lasers system, calculates the signal strength that reaches the receiver. Under certain conditions, the total attenuation of -98.92 dB by calculation, and put forward the related experiment scheme by the use of Atmospheric analog channel, seawater analog channel. In the experiment of the theory, we use the simulation pool of the atmosphere and the sea to replace the real environment where the laser detection system works in this kind of situation. To start with, we need to put the target in the simulating seawater pool of 10 meters large and then control the depth of the target in the sea level. We, putting the laser detection system in position where it is 2 kilometers far from one side, secondly use the equipment to aim at the target in some distance. Lastly, by launching and detecting the signal of returning wave, identify the effect of the image produced by the system.

Low-level laser irradiation has been reported to promote bone formation, but the molecular mechanism is still unclear. Hedgehog signaling pathway has been reported to play an important role in promoting bone formation. The aim of the present study was to examine whether low-level Ga-Al-As laser (808 nm) irradiation could have an effect on Hedgehog signaling pathway during osteoblast proliferation in vitro. Mouse osteoblastic cell line MC3T3-E1 was cultured in vitro. The cultures after laser irradiation (3.75J/cm2) were treated with recombinant N-terminals Sonic Hedgehog (N-Shh)or Hedgehog inhibitor cyclopamine (cy). The experiment was divided into 4 group, group 1:laser irradiation, group 2: laser irradiation and N-Shh, group 3: laser irradiation and cy, group 4:control with no laser irradiation. On day 1,2 and 3,cell proliferation was determined by cell counting, Cell Counting Kit-8.On 12 h and 24 h, cell cycle was detected by flow cytometry. Proliferation activity of laser irradiation and N-Shh group was remarkably increased compared with those of laser irradiation group. Proliferation activity of laser irradiation and cy group was remarkably decreased compared with those of laser irradiation group, however proliferation activity of laser irradiation and cy group was remarkably increased compared with those of control group. These results suggest that low-level Ga-Al-As laser irradiation activate Hedgehog signaling pathway during osteoblast proliferation in vitro. Hedgehog signaling pathway is one of the signaling pathways by which low-level Ga-Al-As laser irradiation regulates osteoblast proliferation.

We report on a high energy laser diode (LD) side-continuous-pumped Nd:YAG (yttrium aluminum garnet) picosecond regenerative amplifier. The mode-locking picosecond oscillator is used as seed source with 31.3 ps pulse width, 150 mW average power and 1064.4 nm center wavelengths at the repetition frequency of 86 MHz. For the amplifier system, average output power of 6.4 W and 10.8 W are achieved at repetition frequency of 2 kHz and 4.5 kHz, which corresponds to output pulse energy of 3.2 mJ and 2.4 mJ respectively. The regenerative amplifier designed has high compact and high stability.

A high-power high-beam-quality 1064nm Nd:YAG rod laser and SHG by intracavity-frequency-doubling are reported. With two common side-pumped Nd:YAG rod modules in the short cavity, we achieved an 78.5W near diffraction-limited pulsed wave 1064nm laser(M²=1.5) with pulse frequency 30kHz, pulse width 94ns and a good power stability of ±1% for over two hours. Finally, a 40W pulsed green laser with pulse width of 92ns in a near diffraction-limited beam (M²=1.45) is generated using an LBO crystal as the frequency doubler in the cavity.

The high-performance InGaAsSb/GaAsSb/GaAs lasers emitting 1300 nm is simulated. Compared to the type-II quantum well GaAsSb/GaAs, In_0.48Ga_0.52As_0.98Sb_0.02/GaAs_0.98Sb_0.22 has large bandoffset which will offer a better electron confinement. And GaAs_0.98Sb_0.22 can reduce the effective strain of the highly lattice mismatched InGaAsSb quantum well. The transparent carrier densities of active unit is as low as 0.72×10¹⁸ cm^-3. The threshold current and slope efficiency of the InGaAsSb/GaAsSb/GaAs three quantum wells laser is equal to 83 mA and 0.62W/A. When the current is over 93 mA, external efficiency will reach 0.72. In order to further enhance the performance of InGaAsSb/GaAsSb quantum well (QW) laser, the asymmetric (0.5 μm/1.5 μm) waveguide structure is also studied.

We present a extended-cavity diode laser (ECDL) with megahertz linewidth by optical feedback from a folded Fabry–Perot cavity, and demonstrate the efficient laser linewidth reduction and frequency stabilization of the optical feedback technique. In our experiments, a folded Fabry–Perot cavity with a finesse of 4750 replaces the reflecting mirror in the traditional ECDL configuration, the folded Fabry–Perot cavity can serve as an optical feedback element, which forces the semiconductor laser automatically to lock its frequency optically to the cavity resonance frequency. The laser’s phase noise is significantly suppressed, and The laser’s linewidth is reduced from about 20GHz to 15MHz.