Phase-locking of a multi-channel radial array CO2 laser

A theoretical analysis of phase-locking in a multi-channel radial array CO₂ laser is presented. The concepts are based on the theories of injection phase-locking and matrix optics. The mutual optical coupling occurring within the central region is demonstrated by theoretical deduction. Interrelated graphs of the coupling coefficient and the distance between the coupling position and the cavity mirror are calculated by numerical simulation. The results of the analysis are in accord with experimental results.     

激光器的部分相干性对光纤激光器阵列相干合成远场图样的影响

考虑光纤激光器阵列相干合成的远场分布时，一般都认为单个激光器的输出光束是理想的高斯光束，实际上受各种因素的影响，一般激光器的输出光束都是一部分相干光.从部分相干光的高斯-谢尔模型出发，首次推导出了当单个激光器的输出光束是部分相干光时，激光器阵列相干合成的远场光强分布模型，并给出了数值模拟计算结果. 关键词： 光纤激光器阵列 相干合成 部分相干光     

LD阵列侧面泵浦棒状激光介质内的光场研究

建立了LD侧面泵浦激光介质内的光场分布数值模型。通过光线追迹方法,简化了介质对泵浦光折射的计算方式。利用Matlab软件数值模拟了泵浦光在介质内的归一化分布。提出获得高质量、高能量的激光输出参数的选取原则。当LD的束腰半径为1μm、LD的数量为40个、介质的半径为1.5mm、发光面到介质的泵浦距离为0.5mm、介质吸收系数在2cm-1～6cm-1之间时,泵浦光在激光介质内的增益分布较好。     

Characterization of the laser cleaving on glass sheets with a line-shape laser beam

A CO₂ laser with a line-shape beam was used to cleave a soda-lime glass substrate at various beam-rotation angles to the cutting direction. The stress distribution on the glass substrate cleaved by the laser beam has been analyzed in this study. An uncoupled thermal-elastic analysis was achieved by the ABAQUS software based on the finite element method. The numerical results show that the stress field of the fracture is caused by a complex stress state and the cleavages are significantly affected by the heat diffusion and beam rotation angle. At the rotation angle of zero degree to the cleaving direction, the phenomena of the chip formation have been found due to a large temperature gradient at the cleaving depth of the glass substrate.     

熔石英表面热致应力对激光损伤行为影响的研究

为了研究热致应力对光学元件损伤特性的影响,通过实验测试退火处理消除热应力和未消热应力石英基片的激光损伤特性,研究了热致应力对石英元件初始损伤阈值、损伤增长阈值以及损伤增长规律的影响.结果表明,热致应力对熔石英光学元件的初始损伤阈值有影响,初始损伤阈值随着热致应力增大而降低;热致应力会加剧激光引发的损伤增长,相同的激光通量下,表面应力越大的区域拥有越高的损伤增长因子,但损伤增长仍遵从指数增长规律.热致应力对损伤增长阈值没有明显的影响.本文的研究将为CO2激光预处理工艺能否被应用于大口径光学元件提供一个必要的技术参考.     

封离式He-N$lt;sub$gt;2$lt;/sub$gt;-CO$lt;sub$gt;2$lt;/sub$gt;激光器横模特性的测量与分析

利用激光光束分析仪,实时在线测量了一根He-N₂-CO₂封离式激光管的横模分布特性,得到了激光模式随放电电流的变化关系.实验表明该激光器在最佳工作电流时,容易形成低阶模运转,但很难获得基模运转,通过改善对称性以及加快冷却水流速可以获得基模运转.通过激光动力学过程分析了模式变化的形成原因,为大功率激光器模式控制与改善提供了一定的理论和实验借鉴. 关键词： 2激光')" href="#">CO₂激光 横模 激光模式分析 光束质量     

Time-resolved spatial structure of TEA CO2 laser pulses

The evolution of the intensity profile of TEA CO₂ laser pulses along the pulse length is investigated both analytically and experimentally. A simple scalar model of the pulse amplitude is introduced, which gives the loaded-cavity modes as a linear combination of bidimensional Hermite-Gauss functions. According to this model a number of equations are derived which link the time-varying spatial structure of the pulse to its time-resolved second-order intensity moments, namely, the beam width and the M² parameter.     

利用外腔改善半导体激光器列阵的远场特性

采用一个由快轴准直透镜和一个高反射率平面镜组成的简单外腔,在腔长为几个cm时实现了半导体激光器列阵中部分单元的锁相运行;DLA远场出现了3个瓣,每瓣发散角为10 mrad左右,对比度为50%;通过控制部分单元的输出,可以抑制旁瓣的能量.     

Modeling of the power oscillation observed in single mode intracavity absorption of CO2 laser lines

Single mode intracavity absorption is investigated from an analytical point of view in order to explain the periodical modulation of the power observed in intracavity absorption of CO₂ laser lines by CFC gases. Intracavity absorption is incorporated into the laser rate equations in form of an additional broadband loss. Detuning due to changes in the refractive index with increase in absorber pressure is accounted for by considering the impact of the frequency shift of the oscillating mode on the effective pump rate and the population densities of the laser upper and lower levels. The steady state solution of the rate equations leads to an analytical formula, which fits the measured intracavity absorption curves with only two fit parameters being adjusted to the actual values of the absorption cross section and the mean linear polarizability of the absorber molecule. The formula is applied to analyze the intracavity absorption of the CO₂ 10R lines by CFC-11. The obtained results are in reasonable agreement with the values available in the literature.     

New far infrared laser lines obtained by optically pumping13CD3OD

We have obtained laser action on 34 far infrared lines for the first time in fully deuterated methyl alcohol with the¹³C isotope (¹³CD₃OD), and we have measured the frequency of 13 lines. The molecule was pumped by a cw CO₂ laser. We have measured the wavelength, the relative polarization, the relative intensity of most lines, the frequency, and the CO₂ pump frequency offset of the strongest lines. The new lines are distributed in the wavelength region from 75.27 m to 464.7 m.Supported in part by a joint grant with the U.S. National Science Foundation grant # INT 80-19014 and the Brazilian Conselho Nacional de Pesquisas (CNPq).     

Injection locked single mode operation of a tea CO2 laser with high energy extraction

Generation of reproducible smooth pulses from longitudinal mode control of a TEA CO₂ laser by signal injection from a cw CO₂ laser is reported and the operating conditions investigated for several new geometries. Applied to unstable resonators, the efficient and spectrally pure, high power output obtains has important application in the area of optical pumping.     

Output mode characteristics of an in-phase locked gain waveguide array CO2 laser

In this paper,experimental and theoretical studies of the output mode characteristics of an in-phase locked gain waveguide array CO 2 laser are reported.The experimental results of the optical oscillation mode frequency,the far-field intensity distribution and the burnt pattern of the sliced waveguide array laser are obtained.A revised mode expression of the rectangle waveguide,which is suited for this waveguide array CO 2 laser,is proposed.The theoretical simulation results based on the revised mode expression are shown to be in good agreement with the experimental results.     

Amplitude-detuning characteristic of a CO2 laser with biharmonic loss modulation

The nonlinear response of a CO₂ laser to biharmonic loss modulation was theoretically investigated for tuning of the radiation frequency within the limits of the amplification band. It is shown that the value and form of the amplitude-detuning characteristic (and, consequently, the temporal and energy parameters of the laser radiation) can be controlled within sufficiently wide limits by changing the modulation frequency and the phase shift of oscillations. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 43–47, January–February, 1999.     

Nonlinear dynamics of the dual-wavelength CO2 laser

Theoretical studies have been made of the nonlinear-dynamic modes of operation of a dual-wavelength CO₂ laser with continuous pumping by electric discharge and loss modulation in one of the lasing channels. It is shown that by varying the modulation depth and frequency, it is possible to control, over a fairly wide range, the time and energy parameters of lasing in both channels, going from regular to chaotic modes of operation. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 316–321, May–June, 2000.     

Design and operation characteristics of a high power transverse flow pulser sustained cw CO2 laser

A transverse flow, transverse discharge cw CO₂ laser in which de discharge is sustained by employing high repetition rate high voltage pulses has been developed. Pulser sustained discharge through electrodes of innovative design provided uniform excitation at electrical input power densities more than 10 W/cc. Laser output power more than 2.5 kW was obtained in a laser gas mixture consisting of 0.5 mbar of CO₂, 16 mbar of N₂ and 38.5 mbar of He. Design details and operational characteristics of this laser are presented.     

Frequency measurements of far infrared12CH3OH laser lines

We have measured the frequencies of 12 known and 3 new submillimeter laser lines obtained by pumping¹²CH₃OH with a cw waveguide CO₂ laser in a Fabry-Perot far infrared resonator. We have also measured the relative polarization and the pumping CO₂ frequency offset for each line.Supported in part by a joint grant with the U.S. National Science Foundation # INT80-19014 and the Brazilian Conselho Nacional de Pesquisas (CNPq).Work of the U.S. Government; not subject to U.S. copyright.     

Optically pumped submillimeter laser lines from CD2Cl2 using a large tunability CW CO2 laser

Twenty-five new laser lines have been obtained in the wavelength region from 155 to 830 μm by optically pumping the CD₂Cl₂ (deuterated dichloromethane) molecule with a CW CO₂ laser having a tunability range of 300 MHz. The wavelength, polarization relative to that of CO₂ pumping radiation, and offset relative to the CO₂ center frequency were determined for all of the new lines and some other already known laser emissions. For all of them we give also the relative intensity and the optimum pressure of operation. Permanent address: Depto de Física e Química da FEIS — UNESP 15.378-000 Ilha Solteira-SP, Brazil     

The power dependence of a carbon-dioxide laser on the gas flow

Summary The gas flow rate has resulted very important to get high power in a CO₂ diffusion-cooled laser. Some measurements suggest that the power dependence on the flow is connected with the chemical dissociation of the components of the gas mixture. Four different gas circuits have been experimented. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

优化封离型CO2激光工作气体的动力学机理研究

详细讨论了封离型CO₂激光器中CO₂，N₂和He三混合气 体含量被优化组合后的激光动力 学机理. 气体优化可以提高激光输出功率的主要机理是通过适当增加N₂含量， 使N₂激发 态与CO₂激光上能级的碰撞频率增加，提高了激光能级粒子数密度和相对布居数 . 同时， 适当减少CO₂含量，使总的电子动量输运碰撞频率减小、放电电流增大，导致增 加激光上转动能级的弛豫 关键词： 2激光')" href="#">CO₂激光 气体动力学 强化机理     

Prediction of the thermal properties of CO2, CO, and Xe laser media

Approximation functions describing the experimental data of thermal conductivity and viscosity of chosen gases (CO₂, N₂, He, Xe, CO, O₂, Ar) are given in the paper. Introduced formulas allow to predict thermal conductivity and temperature distribution of typical high-power laser gas mixture. Examples of temperature distribution in RF excited CO₂, CO, and Xe laser media are shown. Knowledge of the temperature distribution in the laser cavity can be useful for predicting the general properties of laser.