高压螺旋形空心阴极UVCu+激光器

本文研究了高压螺旋形空心阴极紫外(UV)铜离子激光器的工作特性,测定不同螺旋结构激光器的紫外输出功率。在放电长度1.2m,内径6mm,螺距9mm的分段放电管中,在波长260nm时获得最大峰值功率660mW。     

A self-consistent model for negative glow discharge lasers: thehollow cathode helium mercury laser

A model for negative glow metal-vapor ion lasers that self-consistently describes the dynamics of the negative glow and the cathode sheath regions of the discharge has been developed. The model computes the electron energy distribution and the population of relevant excited states in the negative glow self-consistently with the charged particles fluxes and electric field distribution in the cathode sheath. Its application to the study of the helium-mercury charge transfer ion laser is reported. The model accurately depicts the operation of a hollow cathode in the laboratory, where for a defined cathode geometry and material, the discharge characteristics are determined by the selected discharge voltage and the gas pressure. The laser output power calculated as a function of the discharge parameters is in good agreement with experimental measurements reported in the literature. The model can be modified to simulate other negative glow discharge lasers, such as electron-beam pumped CW ion lasers     

High-gain ultraviolet Cu-II laser in a segmented hollow cathodedischarge

We report measurements of the discharge and laser characteristics of an ultraviolet (UV) copper ion laser radiating on the 248.6- and 270.3-nm transitions. Our 50-cm active length laser operates in a high-voltage segmented hollow cathode discharge with Brewster windows and external mirrors. The lowest threshold currents were 7.3 and 5.6 A for the above transitions, respectively. The threshold current was found to increase with decreasing active length. We obtained superior gain characteristics (to 11.2 and 8.8%/m gain for the 248.6-and 270.3-nm transitions, respectively, at 0.3 A/cm linear current density) compared with previous studies on UV Cu ion lasers in conventional hollow cathode discharges     

CW radio-frequency excited white-light He-Cd+ laser

We report on the design and performance of a continuous-wave transverse capacitively coupled radio-frequency excited He-Cd⁺ laser, which is capable of simultaneously delivering stable, tens-milliwatt power output at the three primary spectral lines blue: (λ=441.6 nm), green (λ=533.7 nm and λ=537.8 nm), and red (λ=635.5 nm and λ=636.0 nm). Mixing these lines can result in the laser beam featured by a wide band of colors, including white color. The radio-frequency discharge, that excited the He-Cd mixture inside an alumina ceramic tube (400 mm length and 4 mm inner diameter) inserted into the fused silica tubing, operated between 400 mm long and 4 mm wide outer electrodes. Transformation of the radio-frequency discharge impedance to the 50-Ω output resistance of the radiofrequency generator and symmetrization of the radio-frequency voltage were performed by a special matching circuit. Under single-line operation the He-Cd⁺ laser output powers of 60 mW, 38 mW and 14 mW were obtained for the blue, green and red lines, respectively, at an input radio-frequency power of 400 W. Owing to the power interaction between the laser oscillations at red and green higher laser output powers in red and green are possible under multi-line operation. At optimum conditions the white-light laser output power of about 60 mW is obtainable from the laser tube of 40 cm active length. The rms noise-to-signal ratio (lower than 0.4%) of the laser output power of the radio-frequency excited He-Cd⁺ laser was comparable to that of hollow cathode He-Cd⁺ lasers and much lower than that of conventional positive column He-Cd⁺ lasers. The presented laser has exhibited stable operation for more than 400 hours, showing ability to become a long life laser     

A new design of hollow cathode lasers with multiple electrodes

A new design for hollow cathode lasers, using multiple electrodes excited with an alternating power supply, is introduced and a report on their preliminary performance is given. Laser action was observed on the 781 nm transition of the Cu ion.     

Applications of excimer lasers to laser-radar observations of the upper atmosphere

Development of efficient ultraviolet (UV) rare-gas halide excimer lasers has added new possibilities for laser radar (lidar) technique for monitoring atmospheric constituents. An experimental result of the observation of the stratospheric ozone layer by a XeCl laser (308 nm) based on the differential-absorption-lidar (DIAL) technique is described. The obtained ozone profile in an altitude range of 15- 25 km are in good agreement with those measured by radiosonde. The measurement error is analyzed for one-wavelength lidar. The accuracy is estimated to be 10-30 percent within an altitude range of 10-30 km and at a range resolution of 1 km or less. The accuracy and the resolution are higher than the Umkehr method. Recent progress of rare-gas halide lasers and their frequency conversion techniques as a transmitter for lidar are reviewed. Many powerful and reliable new sources are available in almost every wavelength over the near UV region. New applications of these UV sources to the lidar system are also briefly discussed, especially from the scientific field on the middle atmosphere.     

高功率266 nm全固态单频连续波激光器研究进展

高功率单频连续波266 nm激光在大容量信息存储、高分辨光谱监测及高精度紫外光刻等领域具有重要应用价值,近年来已成为国内外紫外激光领域的研究热点之一。文中首先综合比较了用于产生高功率266 nm紫外激光的非线性光学晶体基本性能,并根据主要的激光器频率锁定方法,重点分析了H?nsch-Couillaud (H-C)频率锁定和Pound-Drever-Hall (PDH)频率锁定方法的优缺点以及连续波单频266 nm激光器发展现状,介绍了本课题组最新研究成果,即基于H-C频率锁定方法实现了功率1.1 W的单频连续波266 nm紫外激光稳定输出。最后,针对进一步提升全固态单频连续波266 nm激光器性能亟需解决的问题和可能解决路径进行了简要分析和展望。     

1 W operation of singly ionized silver and copper lasers

We report a multiline output power of 1 W from the 800.4, 825.5, and 840.4 nm Ag II transitions and 350 mW from the 408.6 nm Ag II transition resulting from pulsed operation of a silver hollow cathode laser. Continuous output of 1 W was obtained in a copper hollow cathode from the 780.8 nm Cu II transition. Design considerations for continuous high-power operation of the hollow cathode discharge are also discussed.     

Multiwatt operation of Cu II and Ag II hollow cathode lasers

We report multiwatt pulsed (120 μs pulsewidth, 40Hz) laser operation of silver and copper hollow cathode lasers. Peak output powers of 65 mW at 224 nm, 500 mW at 248 nm, 1.3 W at 318.1 nm, and 2.3 W at 478.8 nm have been achieved. Measurements of small-signal gains of selected laser transitions and new laser lines in Cu, Ag, Kr, and Ar are presented.     

UV generation by frequency quadrupling of a Yb-doped fiberamplifier

The pulsed output of a Yb-doped fiber amplifier was frequency doubled and quadrupled to generate visible and UV radiation. When pumped with 150-200 mW at 980 nm and seeded at 1064 nm, the amplifier produced an average power of 90 mW at 1064 nm, 45 mW at 532 nm, and 1.4 mW at 266 nm. These results indicate that frequency-converted fiber lasers and amplifiers will be able to replace conventional tunable UV sources (e,g,, frequency-converted dye lasers) in a number of applications     

具有金属纳米颗粒结构的微小孔面发射激光器

在普通850nm垂直腔面发射激光器基础上制备出带有金属纳米颗粒结构的微小孔径垂直腔面发射激光器。当小孔和金属颗粒的直径分别为400nm和100nm时,其最大输出光功率达到0.5mW。介绍了该器件的制备工艺,从实验和理论两方面验证了金属纳米颗粒结构激发局域表面等离子体,从而使输出光功率得到提高。     

空阴极氦-氪离子激光器的实验研究

通过改革HCD He-Kr离子激光器的结构和电源,激光输出特性获得了很好的改善。通过观察各种自发辐射谱线输出波形,分析研究了激光输出波形的形成机理。实验结果指出,阴极溅射是影响He-Kr HCD离子激光器激光输出波形和输出功率的主要原因之一。     

980nm InGaAs应变量子阱激光器及组合件

利用分子束外延技术研制出了高质量InGsAs/GaAs应变量子阱材料及量子阱激光器.脊形波导窄条形量子阱激光器的阈值电流和微分量子效率分别为15mA和0.8 W/A,线性输出功率大于150mW,基横模输出功率可达100mW.InGaAs应变量子阱激光器和单模光纤进行了耦合,其组合件出纤光功率典型值为40mW,最大值可达60mW.显示出了高的基横模输出功率和高的耦合效率.其组合件在40～60mW下,中心发射波长在977nm.满足了对掺铒光纤高效率泵浦的波长要求,成功地研制出适于掺铒光纤放大器用的应变量子阱激光器.     

Second-order DFB lasers fabricated by deep UV contact lithography and GSMBE

DFB ridge waveguide lasers at 1.55 mu m with uniform second-order gratings defined by deep UV lithography have been realised for the first time. The lasers have been fabricated using gas source molecular beam epitaxial (GSMBE) heterostructures grown in a two-step process. The characteristics of the DFB lasers (28 mA minimum threshold current, single-mode behaviour at output power in excess of 5 mW for more than 80% of the lasers and very low dispersion (+or-0.6 nm) of the lasing wavelength) demonstrate that deep UV lithography can be successfully used for the fabrication of DFB lasers.<>     

光泽金属的激光精密刻蚀实验研究

采用266 nm 或355 nm 的紫外激光器可以对微小的金属薄膜器件直接进行激光精密加工。但是,目前紫外激光器的输出功率普遍较低,以至于还不能对大幅面、深尺度的光泽金属进行激光加工。为了克服光泽金属对大功率固体激光器输出的1064 nm 激光的高反射率和散热快问题,采用了优化谐振腔和扫描聚焦系统的光学方法,实现了激光单模运转,功率密度达到了1.592109W/cm2,由此也使得加工工件通过原子吸收激光能量的方式改变为通过金属中的自由电子的等离子体激射来吸收激光能量。在平均功率为50W、重复频率为500 Hz、焦斑直径小于20 m、脉冲宽度为80 ns、切割速度为10 mm/s 的加工条件下,对厚度为10 mm 的大尺寸紫铜板直接进行了激光精密刻蚀实验,切割的槽宽和槽深均为10010 m;槽间距为30015 m,均达到了初始设计的指标要求。     

印刷电路板预电离TEA CO2激光器的阴极表面预电离研究

弧光放电不利于TEA CO2激光器输出高功率激光,通常采用预电离技术来获得主电极间的均匀辉光放电。印刷电路板预电离较其他紫外光预电离方式具有更好的预电离强度和预电离均匀性的结合,有利于产生高重复频率和高平均功率的脉冲激光。本文研究了印刷电路板预电离TEA CO2激光器中有、无紫外光体积光电离的两种不同预电离结构形式,主放电均匀性实验表明,在无紫外光体积光电离的情况下,也可以获得放电均匀性很好的大体积主放电。这说明在印刷电路板预电离中起主导作用的是阴极表面的预电离效应。本研究结果对探讨TEA CO2激光器的预电离放电机理具有参考价值。     

Influence of the active zone diameter, on the UV-ion Ne-CuBr laserperformance

An active-zone-diameter scanning of an ultraviolet (UV) Cu⁺ laser excited in a nanosecond, pulsed longitudinal Ne-CuBr discharge with an excitation pulse repetition frequency of 19.5-25 kHz is carried out. The discharge conditions for achieving a maximum average output power on the UV lines-248.6, 252.9, 260.0, and 270.3 nm are found for each active zone diameter. A record average output power of 1.3 W is obtained for multiline operation. The specific average output power is 57 mW/cm³ at an active volume of 23 cm³. The highest peak pulse power and average laser power on the 248.6-nm laser line for the UV Cu⁺ lasers are also measured-3.25 and 0.85 W, respectively. A simplified kinetic model, which describes the discharge afterglow processes, is made     

Transmission properties of spark preionization radiation inrare-gas halide laser gas mixes

A charge collection apparatus was used to measure photocharge yields and transmission properties of light emitted from a spark preionizer discharge through various rare-gas halide laser gas mixes as well as through their component gas mixes. The data indicates that for HCl partial pressure (p) and photon path length (d) pd products ⩾100 Torr-cm, a narrow transmission window (114-124 nm) for preionization of XeCl and KrCl lasers occurs. In contrast, fluorine based rare-gas halide laser gas mixes were largely transparent over a critical 100-150 nm spectral window responsible for preionization. The role of gaseous impurities, two photon ionization processes, the photoelectric effect, passivation and air contamination on the photocharge signal and light transmission are described     

Linewidth study of InAs-InGaAs quantum dot distributed feedback lasers

The linewidth of laterally loss-coupled distributed feedback (DFB) lasers based on InAs quantum dots (QDs) embedded in an InGaAs quantum well (QW) is investigated. Narrow linewidth operation of QD devices is demonstrated. A linewidth-power product less than 1.2 MHz /spl middot/ mW is achieved in a device of 300-/spl mu/m cavity length for an output power up to 2 mW. Depending on the gain offset of the DFB modes from the QD ground state gain peak, linewidth rebroadening or a floor is observed at a cavity photon density of about 1.2-2.4/spl times/10/sup 15/ cm/sup -3/, which is much lower than in QW lasers. This phenomenon is attributed to the enhanced gain compression observed in QDs.     

银离子空心阴极4788埃激光器

本文报导了一个连续工作的空心阴极放电银蒸气激光器,给出了器件结构和一些实验结果,在50厘米放电长度已获得输出功率30毫瓦.