An all-solid-state high power quasi-continuous-wave tunable dual-wavelength Ti：sapphire laser system using birefringence filter

This paper describes a tunable dual-wavelength Ti：sapphire laser system with quasi-continuous-wave and high-power outputs. In the design of the laser, it adopts a frequency-doubled Nd：YAG laser as the pumping source, and the birefringence filter as the tuning element. Tunable dual-wavelength outputs with one wavelength range from 700 nm to 756.5 nm, another from 830 nm to 900mn have been demonstrated. With a pump power of 23 W at 532 nm, a repetition rate of 7 kHz and a pulse width of 47.6 ns, an output power of 5.1 W at 744.8 nm and 860.9 nm with a pulse width of 13.2 ns and a line width of 3 nm has been obtained, it indicates an optical-to-optical conversion efficiency of 22.2%.

Energy transfer in solid-state dye lasers based on methyl methacrylate co-doped with sulforhodamine B and crystal violet

Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG laser. Distributed feedback dye laser （DFDL） action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism. Theoretically, the characteristics of acceptor and donor DFDLs, and the dependence of their pulse widths and output powers on acceptor-donor concentrations and pump power, were studied. Experimentally, the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor-donor concentrations. Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium. The laser wavelength showed continuous tunability from 563 nm to 648 nm.

Analytical modelling of end thermal coupling in a solid-state laser longitudinally bonded by a vertical-cavity top-emitting laser diode

The intrinsic features involving a circularly symmetric beam profile with low divergence, planar geometry as well as the increasingly enhanced power of vertical-cavity surface-emitting lasers （VCSELs） have made the VCSEL a promising pump source in direct end bonding to a solid-state laser medium to form the minimized, on-wafer integrated laser system. This scheme will generate a surface contact pump configuration and thus additional end thermal coupling to the laser medium through the joint interface of both materials, apart from pump beam heating. This paper analytically models temperature distributions in both VCSEL and the laser medium from the end thermal coupling regarding surface contact pump configuration using a top-emitting VCSEL as the pump source for the first time. The analytical solutions are derived by introducing relative temperature and mean temperature expressions. The results show that the end contact heating by the VCSEL could lead to considerable temperature variations associated with thermal phase shift and thermal lensing in the laser medium. However, if the central temperature of the interface is increased by less than 20 K, the end contact heating does not have a significant thermal influence on the laser medium. In this case, the thermal effect should be dominated by pump beam heating. This work provides useful analytical results for further analysis of hybrid thermal effects on those lasers pumped by a direct VCSEL bond.

Research on All-solid-state Laser and Its Industrial Development in China

Some typical applications of solid-state laser are described, and its industrial development in China are also introduced in detail.

Development and Research on All-solid-state Intracavity Sum-frequency laser

Generation of intracavity multi-wavelength and the basic principle of sum-frequency lasers are discused, and the current research status and development of laser diode pumped lasers are introduced in detail.

Stimulated photoluminescence emission and trap states in Si/SiO_2 interface formed by irradiation of laser

Stimulated photoluminescence （PL） emission has been observed from an oxide structure of silicon when optically excited by a radiation of 514nm laser. Sharp twin peaks at 694 and 692nm are dominated by stimulated emission, which can be demonstrated by its threshold behaviour and linear transition of emission intensity as a function of pump power. The oxide structure is formed by laser irradiation on silicon and its annealing treatment. A model for explaining the stimulated emission is proposed, in which the trap states of the interface between an oxide of silicon and porous nanocrystal play an important role.

Superplastic solid state welding of steel and copper alloy based on laser quenching of steel surface

Based on the feasibility of isothermal superplastic solid state welding of steel and copper alloy, the welded surface of steel surface was ultra-fined through laser quenching, and then the welding process tests between different base metals of 40Cr and QCr0.5 were made under the condition of non vacuum and non shield gas. The experimental results show that, with the sample surface of steel after laser quenching and that of copper alloy carefully cleaned, and under the pre-pressed stress of 56.684.9 MPa, at the welding temperature of 750800 ℃ and at initial strain rate of （2.57.5）×10-4 s-1, the solid state welding can be finished in 120180 s so that the strength of the joint is up to that of QCr0.5 base metal and the expansion rate of the joint does not exceed 6%. The plastic deformation of the joint was further analysed. The superplastic deformation of the copper alloy occurs in welding process and the deformation of steel are little.

Analytical and numerical investigations of displaced thermal state evolutions in a laser process

We investigate how displaced thermal states （DTSs） evolve in a laser channel. Remarkably, the initial DTS, an example of a mixed state, still remains mixed and thermal. At long times, they finally decay to a highly classical thermal field only related to the laser parameters κ and g. The normal ordering product of density operator of the DTS in the laser channel leads to obtaining the analytical time-evolution expressions of the photon number, Wigner function, and von Neumann entropy. Also, some interesting results are presented via numerically investigating these explicit time-dependent expressions.

Transition state to mode locking in a passively mode-locked erbium-doped fibre ring laser

The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.

Microstructure and mechanical properties of laser beam welding 6061 aluminum alloy with different states

With the diversification of manufacture methods, joining the same materials with different states becomes indispensable in practical application. In present work, 6061 aluminum alloys with different states were welded by laser beam welding （LBW）. The microstructures of welded joint, before and after heat treating, were investigated. The mechanical properties, such as the tensile properties and microhardness , were tested. And the fracture characteristic was observed by means of scanning electron microscope （SEM）. The results show that the 6061 aluminum alloys have superior weldability and the microstructures are different significantly in different states. Besides, the grain boundaries of the joint microstructures become unclear after the heat treating. The strength and the elongations of welded joints could reach to those of the base metal. The tensile fracture occurs in the fusion zone and near 6061-0 alloy. And the fracture presents ductile rupture. Therefore, the LBW is an effective method for 6061 aluminum alloy.

Recent progress in matter in extreme states created by laser

I.INTRODUCTION Strong interest in the modeling of planetary interiors,dwarf stars,and the physical conditions necessary to achieve inertial confinement fusion(ICF)have driven attention to the properties of matter at high density,temperature,and pressure(beyond the megabar limit).Extreme states of matter have been studied using gas guns,explosives,and Z-pinches,among other methods(see,e.g.,Refs.1–4).However in recent years,lasers have become the most reliable standard tool for creating extreme states of matter.

New Progress on All Solid State Laser Technology in China

1 Significance of All Solid State Laser (DPL) Technology in Field of LaserBecause of the advantages of high conversion efficiency, good beam quality, small size and light weight, DPL becomes the hotspot and priority of development of laser technology. It may be the main body of laser in the future and replace gas laser and liquid laser. It is a great revolution of laser technology.The developed countries vie in developing DPL. China has achieved great success in this field, but there is a wide gap between the developed countries and us. We should attach great importance to it.

Infrared Laser Pumped Green and Blue Laser Emissions from a Single Solid State Material Doped by Rare Earth Ions

The possible ways and progress of infrared or red laser pumped green and blue laser emissions from a single solid state material doped by rare earth ions are outlined. The green and blue lasers realized from infrared laser pumped rare earth doped nonlinear laser crystals by means of self frequency conversion and from infrared laser pumped rare earth doped bulk, fiber and microsphere materials by means of frequency upconversion are introduced in detail. Other kinds of devices and methods are also compared. The typical nonlinear laser crystals such as YAl 3(BO 3) 4, GdAl 3(BO 3) 4, YCa 4O(BO 3) 3 , GdCa 4O(BO 3) 3, and the typical upconversion fluoride fibers are compared and analyzed. The major problems remaining to be solved and the developing trends in the area are also discussed.

Thermal Analysis of Blue Laser Diode for Solid State Lighting Application

Solid-state light sources based on laser diode are becoming great alternative for LEDs. Improvement of the thermal characteristics of InGaN LD is very important for realizing reliable devices. In this investigation the influence of the temperature of diode on light parameters was studied. White light was obtained by coupling blue light of diode with yellow phosphors: YAG:Ce3+ and GYAG:Ce3+ with nitride. For three values of the temperature of LD’s stem, regulated by Peltier module, CCT, CRI and chromaticity coordinates were measured by spectroradiometer. The importance of emission characteristics of materials was shown. Subsequently, the influence of temperature on laser diode intensity was investigated for 120 hours. This experiment was repeated for different levels of current and temperature. Finally, the steady state of thermal finite element analysis was performed to reveal the distribution of the temperature. The analysis showed the importance of heat sink and also temperature control.

Two-Photon Transitions of ^(85)Rb 5D_(5/2) State by Using an Optical Frequency Comb and a Continuous-Wave Laser

A high-resolution two-photon spectrum of 5S1/2 → 5P3/2 → 5D5/2 transitions in a thermal SSRb vapor cell is presented by using an optical frequency comb and a cw laser. The fluorescence of 6P3/2 → 5S1/2 spontaneous emission is detected when the cw laser frequency is scanned from the 5S1/2 ground state to 5P3/2 hyperfine levels and the optical frequency comb repetition rate is fixed. The hyperfine splittings （Ff = 2-5） of the 5D5/2 excited state are well resolved. The dependences of fluorescence intensities on the cw laser intensity and temperature of SSRb vapor eel1 are studied, respectively. The experimental results are in good agreement with the theoretical analyses.

Simulation of Intermediate State Absorption Enhancement in Rare-Earth Ions by Polarization Modulated Femtosecond Laser Field

We extend the third perturbation theory to study the polarization control behavior of the intermediate state absorption in Nd^（3＋）ions. The results show that coherent interference can occur between the single-photon and three-photon excitation pathways, and depends on the central frequency of the femtosecond laser field. Moreover,single-photon and three-photon absorptions have different polarization control efficiencies, and the relative weight of three-photon absorption in the whole excitation processes can increase with increasing the laser intensity.Therefore, the enhancement or suppression of the intermediate state absorption can be realized and manipulated by properly designing the intensity and central frequency of the polarization modulated femtosecond laser field.This research can not only enrich theoretical research methods for the up-conversion luminescence manipulation of rare-earth ions, but also can provide a clear physical picture for understanding and controlling multi-photon absorption in a multiple energy level system.

Engineering steady-state entanglement for two atoms held in separate cavities through laser cooling

We propose a scheme to prepare the steady-state entanglement for two atoms, which are held in separate cavities that are coupled through a short optical fiber or optical resonator. The entangled steady-state with a high fidelity can be achieved even with a low cooperativity parameter, by making use of the driving laser fields. Such a cooling mechanism is based on a resonant laser pump of the unwanted ground states to the excited states, which finally decay to the desired steady-state.

High harmonic generation in crystal SiO_(2) by sub-10-fs laser pulses

The high harmonic generation(HHG)by few-cycle laser pulses is essential for research in strong-field solid-state physics.Through comparison of high harmonic spectra of solids generated by laser pulses with varying durations,we discovered that lasers with good dispersion compensation are capable of producing a broad spectrum of high harmonics.As the pulse duration is further compressed,several interference peaks appear in the broad spectrum.Moreover,we conducted simulations using the semiconductor Bloch equation,considering the effect of Berry curvature,to better understand this process.Our work provides a valuable approach for studying HHG by few-cycle laser pulses in solid materials,expanding the application of HHG in attosecond physics.

Time-resolved K-shell x-ray spectra of nanosecond laser-produced titanium tracer in gold plasmas

A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The timeresolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By comparing the simulated spectra obtained by using the FLYCHK code with the measured titanium spectra, the temporal plasma states, i.e.,the electron temperatures and densities, are deduced. To evaluate the feasibility of using the method for the characterization of Au plasma states, the deduced plasma states from the measured titanium spectra are compared with the Multi-1D hydrodynamic simulations of laser-produced Au plasmas. By comparing the measured and simulated results, an overall agreement for the electron temperatures is found, whereas there are deviations in the electron densities. The experiment–theory discrepancy may suggest that the plasma state could not be well reproduced by the Multi-1D hydrodynamic simulation, in which the radial gradient is not taken into account. Further investigations on the spectral characterization and hydrodynamic simulations of the plasma states are needed. All the measured and FLYCHK simulated spectra are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.57760/sciencedb.j00113.00032.