Infrared diode laser spectroscopy

Three types of lasers (double-heterostructure 66 K InAsSb/InAsSbP laser diode, room temperature, multi quantum wells with distributed feedback (MQW with DFB) (GaInAsSb/AlGaAsSb based) diode laser and vertical cavity surface emitting lasers (VCSELs) (GaSb based) have been characterized using Fourier transform emission spectroscopy and compared. The photoacoustic technique was employed to determine the detection limit of formaldehyde (less than 1 ppmV) for the strongest absorption line of the v₃ + v₅ band in the emission region of the GaInAsSb/AlGaAsSb diode laser. The detection limit (less than 10 ppbV) of formaldehyde was achieved in the 2820 cm⁻¹ spectral range in case of InAsSb/InAsSbP laser (fundamental bands of v₁, v₅). Laser sensitive detection (laser absorption together with high resolution Fourier transform infrared technique including direct laser linewidth measurement, infrared photoacoustic detection of neutral molecules (methane, form-aldehyde) is discussed.     

Free-running emerald laser pumped by laser diode

Free-running emerald laser pumped by 660-nm laser diode (LD) was reported. Free-running output powerof 24 mW has been obtained with overall efficiency of 1.4% and slope efficiency of 11.9% when the LD incident power was 2.56 W. The laser threshold value of emerald crystal was estimated to be 0.7 W.     

Phase perturbation investigation of laser diode for the laser diode to single-mode fiber coupling system

A novel phase-perturbation method as well as an experimental system were established to study the deviation of the laser diode (LD) far-field intensity distribution from the ideal Gaussian. An analytical expression of the LD far-field intensity distribution and a numerical method based on the Monte Carlo calculation were developed to fit the measured results. The loss of the LD to the single-mode fiber (SMF) coupling system caused by this kind of deviation of the LD far-field intensity distribution was quantitatively analyzed.     

Electronically tunable external-cavity laser diode

We present a new concept for an electronically tunable diode laser. It is based on an external-cavity configuration with simultaneous feedback and intracavity spatial separation of the laser's spectral components. The electronical tunability is achieved by insertion of a liquid-crystal array as an electronically controlled aperture into the region of spatial separation of the spectral components. Wavelength tunability without mechanical movement over a range of 10 nm and two-color operation are demonstrated with a 670-nm laser diode.     

Mode-hop-free electro-optically tuned diode laser

A tunable external-cavity Littrow diode laser, with an intracavity electro-optical crystal, which combines a large mode-hop-free tuning range with high tuning speeds and high tuning accuracy, has been designed. A mode-hop-free single-mode tuning range of 50 GHz at 793 nm with an output power of 60 mW and tuning speeds of 1.5 GHz/micros is demonstrated. The instantaneous linewidth is smaller than 300 kHz. Generally mode-hop-free tuning is obtained when the elongation of the cavity is proportional to the cavity length measured anywhere across the beam. This elongation is achieved with an intracavity crystal in which the thickness, and thus the electric field inside it, varies across the beam.     

高密度封装二极管激光器阵列

 理论模拟了自制的高效冷却器的散热能力,分析了单元封装结构所需材料的导热特性,获得了高功率二极管激光器在高功率密度、高占空比条件下运行的可行性。改进了高密度封装的关键工艺,热沉金属化层达到了3~5 mm,焊料厚度为4~7 mm,封装间距0.6 mm,采用峰值功率1 kW的背冷式叠阵二极管激光器。实验测试结果表明:封装的二极管激光器叠阵单元的整体封装热阻为0.115 ℃/W,有良好的散热能力;该叠阵模块在电流为100 A、占空比15%时,输出峰值功率为986 W,峰值功率密度达到1.5 kW/cm2,平均每个板条的斜效率为1.25 W/A,激光器阈值电流为20 A左右。     

Infrared dye laser excited by a diode laser

A waveguide dye laser with an inner diameter of 30 μm and a length of 1.0 nm has been excited with a pulsed GaAlAs diode laser. The infrared-absorbing dye 5,5′-dichloro-11-diphenylamino-3,3′-diethyl-10,12-ethylenethiatri- carbocyanine perchlorate was used in tetramethylene sulfoxide solution. By changing dye concentration, laser wavelengths from 950 to 1005 nm were obtained.     

半导体激光器发射光谱实验仪

设计了一种半导体激光器发射光谱实验仪 ,可以用来观测LD发射的荧光光谱、激光光谱 ,以及了解光栅外腔选取单纵模、压窄线宽、波长调谐的机理 .该实验仪结构紧凑 ,物理概念清晰 ,适用于大专院校的光学实验教学     

Mid-infrared diode laser spectroscopy of SO

The absorption spectrum of the fundamental band of SO⁺ (X²Π) has been recorded using a mid-infrared tunable diode laser spectrometer with the velocity modulation technique in an AC glow discharge of He/SO₂. Forty-two lines of SO⁺ were identified in the spectral range of 1230-1330 cm⁻¹. The observed rovibrational transitions together with the microwave data published previously were fitted to a standard effective Hamiltonian for ²Π states. Molecular constants for the ground and υ = 1 vibrational states were derived. The band origin was determined to be 1291.5299(27) cm⁻¹.     

现代激光应用技术——激光二极管点火

本文简述了激光二极管点火的优越性；从光学技术角度概括分析了与激光二极管点火技术密切相关的激光二极管技术，光纤及光纤耦合技术，光敏化技术和测试技术及其发展状况。对国外在激光二极管点火方面的研究成果做了一定的介绍。     

On the interaction mechanisms between a high-power diode laser source and silver alloys: The case of aesthetic welding

Welding process is generally considered as a crucial stage in the manufacturing of decorative items in silver alloys. It is mostly hand-made by using oxy-fuel torch and the final performance of the manufactured goods is too strongly related to the capability of skilled technicians and to the settings of factors often unpredictable. Further, spreading and out-of-control oxidative phenomena, troublesome reprocessing of the welded parts and unsafe operational conditions are determining a progressively growing demand for alternative welding technologies.The matter of the present investigation is therefore to evaluate the suitability of a high-power diode laser source in automatic butt-welding of sheets in ‘800/1000’ and ‘925/1000’ silver alloys. Interaction mechanisms between laser beam and underlying silver substrates in a chemical active environment were studied. A ‘first approximation’ oxidation model and, accordingly, simple tools for monitoring and control of the welding process was then proposed. Finally, butt-welding of thin silver sheets was successfully experimented.     

Rubidium vapor laser pumped by two laser diode arrays

Scaling of alkali lasers to higher powers requires using multiple diode lasers for pumping. The first (to our knowledge) results of a cw rubidium laser pumped by two laser diode arrays are presented. A slope efficiency of 53%, total optical efficiency of 46%, and output power of 17 W have been demonstrated.     

二极管抽运铷蒸气激光的物理特性

结合激光微观动力学和热传学,充分考虑到发射激光时的各能级粒子数和热力学分布特性,建立了用于分析二极管抽运铷金属蒸气激光物理特性和增益腔内的温度分布模型,得到了抽运功率和激光输出、光-光转换效率及各物理参数之间的关系,分析了有效提高抽运能量吸收的具体措施,揭示了2P3/2和2P1/2两个精细能级之间的集居数弛豫对半导体抽运碱金属蒸气激光器(DPAL)物理特性的影响。结果表明：在设计不同用途DPAL时,必须要综合考虑各种因素,以确定相应的最佳结构参数。     

二极管泵浦高能激光研究进展和展望

高能激光广泛应用于材料加工、科学研究、空间碎片清除、军事应用等领域。二极管泵浦高能激光具有结构紧凑,系统简单、全电驱无限弹仓的特点,近年来,各类二极管泵浦高能激光围绕着同时实现高功率、高效率、高光束质量这一总目标发展迅速。详细综述了国内外高平均功率块状固体激光、高功率可见光波段激光、高峰值功率激光、高功率光纤激光、碱金属蒸气激光等二极管泵浦高能激光的研究进展,并对其发展趋势进行了展望。     

Xenon saturation spectroscopy by diode laser

Summary Commercial diode lasers have emission wavelengths which overlap some absorption xenon lines. We have performed saturation spectroscopy of four lines, leaving from the first excited atomic configuration 5p ⁵6s, at 823.16 nm, at 828.01 nm, at 834.68 nm and at 820.63 nm, in a weak glow discharge of natural xenon. Natural xenon is a mixture of several isotopes, and the two even isotopes, Xe(129) (26% of relative abundance) and Xe(131) (21%), have a nuclear spin (1/2 and 3/2, respectively) that produces a hyperfine structure. The complex resulting spectra have been resolved and the results are compared with the available literature data. The authors of this paper have agreed to not receive the proofs for correction.     

Power semiconductor laser diode arrays characterization

Nowadays, power semiconductor laser diode arrays are becoming a widespread source for a large variety of industrial applications. In particular, the availability of low-cost high-power laser diode arrays makes their use possible in the industrial context for material cutting, welding, diagnostics and processing. In the above applications, the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. In this paper, we present two different approaches useful for the characterization of the beam quality in laser diode arrays. The first one, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The second one is aimed at the measurement of a global quality factor of the array itself; to this end, the empirical extension of the M² concept to composite beams is presented along with some experimental results. As the first technique is especially intended for the non-destructive detection of design problems in the array itself and in the bias circuitry, the second one represents a powerful tool for the rapid on-line diagnostics of the laser beam during its use.     

kW级光纤耦合输出二极管激光器模块

基于二极管激光器mini-bar的光纤耦合方式是一种降低耦合系统成本并提高整体转换效率的方法, 为此,采用40片封装在铜微通道冷却器上的连续60 W二极管激光器mini-bar组成空间叠加阵列,作为耦合光源,采用非球面柱透镜及柱透镜阵列对mini-bar叠阵进行了快轴与慢轴的准直,实现了两列叠阵的激光束沿快轴方向的空间合成以提高叠阵激光束的填充因子,合成后的激光束可以耦合进入芯径为800 m、数值孔径为0.22的光纤。测试结果表明,光纤耦合模块输出功率最高为1360 W,整体光光效率58%,光纤端面的功率密度达到1.73105 W/cm2。     

GaInAsP/InP surface-emitting laser diode

In this review paper, we will introduce the advantages and laser characteristics of GaInAsP/InP surface-emitting (SE) lasers. In order to obtain the room temperature oscillation of the SE laser diodes, it is very important to reduce not only its threshold current density but also threshold current itself. To decrease its threshold current density and/or its threshold current, we investigated some possible SE laser structures. First, we tried to reduce the threshold current density by introducing (i) a Au/SiO₂ mirror, (ii) a dielectric multilayer mirror to increase the n-side (output-side) reflectivity, and (iii) multi-active-layer structure. Next, to reduce the threshold current, certain types of current confining structure, namely (i) a round-high-mesa/polyimide-buried structure, (ii) a planar buried heterostructure (PBH), (iii) a circular buried heterostructure (CBH) with SiO₂ mask and (iv) a flat surface circular buried heterostructure (FCBH), were investigated. The threshold current of the SE laser was reduced to 18 mA and its highest operation temperature was raised to 263 K (–10°C).