超脉冲CO_2激光器的原理和应用

本文介绍了超脉冲CO2激光器的原理、光学性能、稳定度,通过对比论证了超脉冲技术以及射频激励技术的优势。采用超脉冲射频激励CO2激光器不但具有较高的峰值功率而且具有更好的节能型、稳定性和美观度。     

两台同类型号独立激光器频率稳定度的测量

采用拍频法对两台同类型号独立激光器的稳定度进行了测量。从拍频理论出发,得到了拍频信号稳定度与待测激光器和参考激光器稳定度三者所满足的平方和关系,对于稳定度一致的两台同类型号激光器,由拍频信号稳定度可以得到待测激光器的稳定度。实验中将New Focus公司生产的两台同类型号激光器(TLB-6017)进行拍频,根据拍频信号稳定度测得激光器稳定度为1.36×10-8,频率漂移量为5.1MHz(1s积分时间)。实验结果与激光器出厂指标[稳定度1×10-8、频率漂移量5MHz(1s积分时间)]相比,稳定度在同一量级,频率漂移量的相对误差为2%。此方法避免了通常测量激光器稳定度时所需的高稳定度参考光源的限制,为激光器稳定度的测量提供了一定的参考。     

相位差法激光器频率稳定度测试仪

南京工学院电子工程系研制成功的相位差法激光器频率稳定度测试仪,用于测量激光器频率稳定度。它的特点是在原理上使用激光器的相位变化来测量激光器输出的激光束的频率稳定度;所解决的关键技术是利用     

高功率轴快流CO2激光器控制系统的研制

为了提高高功率轴快流CO2激光器的稳定性和智能化程度,以满足激光加工的需要,采用可编程逻辑控制器和尾镜取样功率稳定技术,研制出了以西门子可编程逻辑控制器为核心的高功率轴快流CO2激光器控制系统,并在4kW轴快流CO2激光器上进行了实验验证,取得了气压稳定度、功率稳定度、放电波形以及激光模式等实验数据,气压波动小于±50Pa,功率稳定度达到±0.1%,并可实现连续、脉冲、超脉冲放电。结果表明,该套控制系统可以满足高功率轴快流CO2激光器的控制需求,提高了高功率轴快流CO2激光器的稳定性和智能化程度。     

GO2稳频激光器和波导激光器的一种简易稳频测试方法

在CO2红外激光外差接收技术中,对CO2激光器的频率稳定度要求很高.现有的稳频测试方法及测试数据处理均比较麻烦.本文首先证明了CO2激光器的辐射频率作为随机变量服从正态分布规律.利用GS-79双管外差探测和x-y记录仪组成的组合系统,很方便地测得7007型和7x005型波导激光器的频率稳定度.     

用于激光磁共振光谱的CO激光器的稳频研究

本文讨论了用于激光磁共振光谱的CO激光器机械与电子的稳频措施,在文中提出了一种新的激光频率稳定度的测量方法,它是以分子的激光磁共振谱线为基准,通过测量分子的激光磁共振谱线线宽及其变化,然后用阿仑方差进行数据处理,最后得出激光频率稳定度。运用这种方法对稳频CO激光器进行了调试和检测,测得在非稳频和稳频条件下CO激光器的频率稳定度分别为1.5×10~(-7)、5.5×10~(-9)。     

声光调Q CO2激光器的实验研究

为满足13.5 nm极紫外光刻(EUVL)等领域的应用需求,研制了高重复频率、高稳定性的声光调Q CO2激光器。首先,对声光Q开关的工作原理进行了分析,并实验研究了调制信号电压与衍射效率的关系。接着,研究了调制信号占空比对脉冲波形的影响,通过选择适当的占空比消去了脉冲拖尾。然后,对不同重复频率下的脉冲宽度、功率和脉冲幅值稳定性进行了测量和分析。最后,对激光器的光束指向稳定性进行了测量。实验结果表明:该激光器实现了重复频率1~100 kHz连续可调的脉冲输出,在重复频率1 kHz时,获得最小脉冲宽度252 ns和最大峰值功率7 579 W的激光脉冲输出。通过设计以殷钢管为主体的支撑架,使得激光器的脉冲幅值不稳定性小于3%,光束指向稳定性为46.6 rad。该声光调Q CO2激光器可作为高性能种子源在EUVL等领域中得到应用。     

紫外预电离TEA CO2激光器的实验研究

介绍了采用火花针紫外预电离高重复频率TEA CO2激光器系统的结构及其实验研究结果.该激光器的脉冲放电行为由旋转火花开关和高压脉冲触发器进行控制,并通过自动翻转电路实现对称张氏电极之间的均匀辉光放电.通过改变激光器工作气体气压、充气配比及注入能量,测量单脉冲输出能量.实验结果表明,激光器的输出能量及电光转换效率随CO2或N2充气压改变存在最佳点,最佳点与注入能量有关.输出能量及电光转换效率与总充气压呈线性关系.该激光器在单脉冲放电条件下比在高重复频率时能够注入更多的能量和充入更高的气压,脉冲能量最大输出可达53J以上,经过进一步地参数优化,该激光器最高的电光转换效率达到17%以上.     

被动式稳频 CO_2激光器频率稳定度的测量

在许多对激光频率稳定度要求不很高的应用领域,大都采用设备简单、运行方便的被动式稳频方法,但都只是估算频率稳定度,很少有人实测。本文利用拍频法测量了被动稳频CO_2激光器的频率稳定度,所得结果对被动稳频气体激光器的使用者有一定的参考价值。实验中所用的两台全外腔式 CO_2激光器的光学谐振腔均由凹面光栅和平面输出镜组成,用殷钢棒作谐振腔的间隔器,放电管用石英玻璃烧制,光栅端用有机玻璃罩罩住防气流     

利用光谱测量脉冲激光频率的稳定性

多普勒测风激光雷达中脉冲激光频率的稳定性是一个重要参数.使用高分辨率F-P标准具的多光束干涉法来测量脉冲激光频率稳定度.其原理是将脉冲激光的多光束干涉成像到面阵CCD上,通过测量中心干涉环直径的变化来获得脉冲激光的频率稳定性.利用此方法对波长为1.064μm,重复频率为1 Hz的被动调Q Nd:YAG激光器,连续测量20 min,获得1 200幅图像.通过对这些图像进行移动平均、阈值选定、循环比较、三阶样条插值等数值方法处理,结果表明其长期稳定性优于10-7.     

激光平网雕刻机设计

研制了用于制作平面网版的激光雕刻机，设计了雕刻机用CO2激光器、光路系统及单片机控制系统，探讨了将图像文件转化为控制命令文件的方法。     

影响RF激励CO2波导激光器高效运转的因素

着重讨论了影响ＲＦ激光ＣＯ２波导激光器高效运转的几个因素,指出要提高ＲＦ功率的高效转换,必须获得均匀稳定的放电,其中阻抗匹配技术,ＲＦ源频率,气体混合比等起着重要作用。     

红外激光心肌打孔规律的实验研究

报告了CO_2激光和Er:YAG激光在心肌组织上进行打孔的实验结果。给出了三条实验曲线:输出功率为100W时,CO_2激光心肌打孔的孔深和打孔时间的关系曲线;打孔时间为0.3s时,CO_2激光心肌打孔的孔深和输出功率的关系曲线;脉冲能量为500mJ时,Er:YAG激光心肌打孔的孔深和脉冲数的关系曲线。并对实验结果进行了分析研究,为激光心肌血管重建术的临床应用提供了一个参考。     

利用反馈环路稳定CO_2激光器的功率

本文报导CO_2激光器功率稳定环路的构成与性能。以荧光饱和吸收稳频的CO_2激光作基准,测定了功率稳定后的频率稳定性,结果表明,功率稳定可改善频率的长期稳定性。     

Laser frequency control using an optical resonator locked to anelectronic oscillator

A new method for controlling a laser's center frequency is reported. This method extends the Pound-Drever-Hall technique, which delivers exceptional laser linewidth. The new technique, applicable over a broad range of wavelengths, produces a laser beam with both narrow linewidth and stable center frequency. A diode-pumped ring laser is locked to an ultrahigh-finesse, tunable optical resonator which, in turn, is locked to an electronic (5 MHz) oscillator using a difference frequency developed by locking a second laser to the resonator. A 1064-nm beam is reported with linewidth less than 0.004 Hz and center-frequency stability given by the electronic reference. For the case of an oven-controlled quartz crystal, the laser center-frequency stability is less than 1 part in 10¹¹ per day with root Allan variance of 10^-12 for a 1000-s time delay. The entire system is compact, and all elements are solid-state, making it useful both in the laboratory and in a number of space-based applications     

Measurement of gain saturation coefficients in strained-layermultiple quantum-well distributed feedback lasers

Gain saturation coefficients of unstrained- and strained-layer multiple-quantum-well lasers were measured experimentally. These coefficients were higher in lasers that had compressive strain in their active-layer wells: 2.45×10^-17 cm³ with unstrained wells and 12.6×10^-17 cm³ with strained wells. The higher gain saturation coefficient in lasers with strained active-layer wells is related to their higher linear TE mode gain coefficient. The linearity factor (K factor) between a laser's damping constant and the square of the laser's resonant frequency decreased slightly with the introduction of the strain in the laser's active layer wells. This factor, however, took the value of about 0.2×10^-9 s for each of these lasers     

基于温度闭环反馈的He-Ne激光器热稳频系统

为了提升激光回馈测量系统中He-Ne激光器的性能, 解决激光回馈镜不断移动时频率无法使用传统方法稳定的技术问题, 采用基于温度反馈控制激光器管体温度的闭环被动稳频的方法, 进行了理论分析和实验验证, 研究了不同管体温度与环境温度差值下频率稳定性。结果表明, 系统最佳温差为25.6℃; 在此温差条件下稳频后, He-Ne激光器波长波动范围达10-4, 即频率稳定性达到1.61×10-7, 功率漂移量低于3.20%。该系统可以根据环境温度的变化调节稳频温度点, 并且稳频结构简单, 满足激光回馈一般应用系统稳定性的要求。     

Measurement of gain saturation coefficient of a DFB laser forlasing mode control by orthogonal polarization light

The frequency response of a 1.55-μm distributed feedback (DFB) laser is measured by injecting light which has an orthogonal polarization to the laser's lasing mode. The injected light, termed as orthogonal polarization light, is carefully selected to not couple to the lasing mode by adjusting its polarization to be orthogonal to that of the lasing mode and by setting its wavelength slightly different from that of the lasing mode. The wavelength of the orthogonal polarization light, however, is set within the range where the laser's active layer has a gain. The gain saturation coefficients for the lasing light are estimated to be 4.7×10^-23 cm² and that by the injected orthogonal polarization light (almost the same wavelength as the lasing mode) are 3.7×10^-23 cm², respectively     

Acoustooptic modulation resonances of injection lasers

A new approach is presented that explains the modulation resonance behavior of AlGaAs injection lasers as a consequence of collisions between photons and phonons in the lasing medium. The theory is applied to relate the laser's refractive index step with the measured modulation resonance frequency. Symmetrically located resonance peaks observed on unmodulated laser spectra are also explained with the new theory, which is compared with the conventional rate equation approach. Experimental data for modulated and unmodulated laser spectra and numerical calculations are presented in support of this acoustooptic theory.     

机载激光雷达测量二氧化碳浓度误差分析

差分吸收激光雷达是高精度测量大范围二氧化碳浓度的有效手段。研究了机载路径积分差分吸收激光雷达测量二氧化碳柱线浓度的主要误差项,分析了这些误差项导致的二氧化碳柱线浓度反演误差。介绍了机载差分吸收激光雷达基本工作原理,并理论分析了大气温度、压强和水汽不确定性误差,激光频率稳定性和飞机姿态速度测量不确定性等系统误差,以及不同地表反射率产生的随机误差。分析结果表明:在二氧化碳浓度380 ppm(1 ppm=10-6)时,机载激光雷达二氧化碳柱线浓度综合测量误差约为0.71 ppm,满足1 ppm的二氧化碳柱线浓度高精度测量需求。