An alignment technique for a ring laser cavity

We present a practical method for fast alignment of a ring laser cavity. With the aid of an auxiliary HeNe laser a closed path is formed in the cavity so that laser action can be quickly attained.     

A simple technique for the alignment of a ring resonator

A simple technique for the alignment of a ring resonator is presented. The positional and the directional alignments are obtained by the movements of independent mirrors. The effects of alignment inaccuracies on the performance of a ring resonator are discussed.     

A simple positive-step alignment technique for a ring resonator

A quick and simple technique is presented for the alignment of a ring resonator of any configuration and any number of mirrors, given that a laser power source of variable gain is available. The method used ensures that the resonator is known to be aligned—a distinct advantage over former techniques.     

Simple technique for alignment of a dispersive ring laser cavity

A simple technique for the alignment of a dispersive ring cavity consisting of a reflection-grating and two mirrors is described. Lasing on different rotational–vibrational transitions of CO₂ molecule is achieved in the ring configuration.     

A simple ring resonator system

A simple technique for the alignment of a three mirror ring cavity system is described. It is also shown that walk-off and astigmatism problems can be eliminated with relative ease, providing notable advantages over alternative travelling wave cavity configurations.     

Numerical analysis of a CO2 SFUR laser cavity

Summary In this paper we present a numerical study of the SFUR (self-filtering unstable resonator) cavity resonant modes and numerical results are compared with the experimental data. The numerical code developed for analysing the SFUR cavity will also allow for studying a wider class of resonators, and is therefore a very useful tool in designing new laser cavities.     

高功率激光装置光束准直系统新型远场监测技术

利用高功率激光装置空间滤波器小孔成像和取样光栅的衍射,设计出一套新型光路远场监测方案,并且在实验平台上进行了实验验证.实验结果表明：相对传统的远场监测方法,该远场监测系统通过侧面离轴光栅取样灵活利用空间,其调整平均误差为空间滤波器小孔直径0.9%,能够满足准直系统远场调整精度(<小孔直径5%)的要求. 关键词： 激光技术 光束准直 光栅 远场     

Deep penetration welding using a CO laser with an unstable resonator

An unstable resonator (M = 2) has been applied to reduce the beam divergence of a gas-dynamically cooled supersonic CO laser operating at 105 K in a semiclosed gas cycle. A 4.7 kW laser beam with a total divergence of 2.5 mrad is obtained with an efficiency of 9.4%. The results of welding experiments are compared with those using a CO₂ laser. The weld depths obtained with the CO₂ laser are drastically reduced using argon as the assist gas, whereas the results with the CO laser are independent of the assist gas because of the lower plasma absorption coefficient for the shorter CO laser wavelength.     

Theoretical studies on beam parameters of a self－start ring cavity Ti：sapphire laser

Ｔｈｅｏｒｅｔｉｃａｌ ｓｔｕｄｉｅｓ ｏｎ ｂｅａｍ ｐａｒａｍｅｔｅｒｓ ｏｆ ａ ｓｅｌｆ－ｓｔａｒｔ ｒｉｎｇ ｃａｖｉｔｙ Ｔｉ：ｓａｐｐｈｉｒｅ ｌａｓｅｒ￥ＺＨＡＮＧＧｕｉｚｈｏｎｇ；ＺＨＥＮＧＸｕｅｍｅｉ；ＷＡＮＧＱｉｎｇｙｕｅ（Ｄｅ...     

An optical technique to measure the frequency and mode emission of tunable lasers

Summary To use mode tunable lasers it is necessary to measure the laser frequency and the mode emission. This problem is very important when waveguide lasers are used. Normally this information is obtained by a heterodyne technique, but there are some difficulties to perform this method in a large electrical noise environment, when pulsed or radiofrequency lasers are used. We have obtained this laser information by using an alternative low-cost optical system. With this apparatus we have measured the cavity pulling and roughly estimated an upper limit for the linewidth of a radiofrequency, high pressure, line and mode-tunable, CO₂ laser.

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Riassunto Nell'impiego di lasers accordabili in modo è necessario misurare la frequenza. Normalmente questa misura è derivata da tecniche eterodina, ma ci sono grosse difficoltà in presenza di un grosso rumore elettromagnetico di fondo, come quando viene usata una eccitazione a radiofrequenza. Le stesse informazioni possono essere ottenute con metodi ottici; per esempio con questa tecnica noi abbiamo misurato lo spostamento di cavità e la larghezza di banda di un laser ad alta pressione a CO₂ alimentato a RF accordabile 500 MHz in modo.

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Резюме Для использования настроенных лазеров необходимы измерения частоты и моды излучения. Зта проблема является очень важнои, когда используются волноводные лазеры. Обычно зта информция получается с помощью гетеродинной техники, но возникает ряд трудностей при применении этого метода из-за высокого злектрического шума скружающей среды, когда используются импульсные или радиочастотные лазеры. Мы предлагаем получать зту информацию о лазерах, используя альтернативную оптич ческую систему с низкой стоимостью. С помощью этой аппаратуры мы измеряем резонатор и грубо оцениваем верхний предел длины волны радиочастотного настроенного CO₂ лазера с высоким давлением.

     

腔镜倾斜对平面环形腔激光振荡模式的影响

从Fox-Li迭代法出发,用光学仿真软件GLAD实现了对平面环形腔的建模。利用此光学模型进行了腔镜倾斜对其本征模式影响的研究,给出了腔镜在两个方向不同倾斜角度下的谐振腔模式光强分布、光强峰值点位置及谐振腔损耗的变化。研究结果表明：腔镜倾斜使平面环形腔模式发生畸变,随着腔面倾斜加大,腔损耗增大,光强峰值点向镜边沿偏移,且腔镜在垂直于腔面方向上的倾斜对振荡模式的影响比腔镜在腔面内的倾斜对振荡模式的影响大。     

A compact fir ring laser with open resonator and variable output coupling

We describe the design, construction and first experimental results with an open triangle FIR ring resonator with Michelson interferometer output coupling, which we combined with a Brewster-windowless 10W CO₂ pump laser to a compact laser package of 1m length. The achieved stability of power and frequency of this system is very high, typically on the order of ±0.01% over several hours and <20kHz per hour at 800GHz. For the design, we investigated the balance of all laser processes and determined the optimum dimensions for the open resonator cavity. This analysis is based on a radially homogenous overall laser model, including commonly accepted simplified rate equations together with molecular parameters for weak FIR laser lines. In accordance with the modelling the efficiency on the very most prominent lines is better than with conventional waveguide lasers, giving up to 4 times better efficiencies especially on lines with low absorption pump transitions. Several laser lines, however, have substantially enhanced pump thresholds on purely copropagating emission, suppressing laser operation below about 10W pump power threshold. We show that this can not be due to effects from the interferometer.     

Chromium doped forsterite ring laser

Operation of a Cr⁴⁺: Mg₂SiO₄ crystal in a ring cavity is studied with different dopant levels. Threshold energies of 13 mJ, 10.6 mJ and 11 mJ were measured for Mitsui low-doped, Russian and Mitsui highly doped crystals respectively. Slope efficiencies of 0.9%, 1.1% have been obtained for the Mitsui low-doped and Russian crystals. An efficiency of 3.6% was recorded for the highly doped chromium forsterite crystal from Mitsui. The peak output wavelength is 1275 nm. These results are compared with these crystals in the simple cavity.     

带非谐振环激光谐振腔的特性

本文中分析了带非谐振环激光谐振腔的光学对称性、稳定性和光束腰位置,可以据此选择谐振腔参数。     

Proposal of a semiconductor ring laser gyroscope

We proposed a novel optical inertial rotation sensor using a semiconductor ring laser (SRL). The frequency difference between the two counter propagating oscillation frequencies was automatically generated in a mechanically rotated SRL, which consisted of a pig-tailed laser diode amplifier module. And the Sagnac frequency shift could be detected at the first time as a beat note by the terminal voltage change of the SRL without branching the circulating optical power. These experimental results verify that an SRL operates as an optical inertial rotation sensor based on the Sagnac effect.     

自由电子激光器的掠射环形谐振腔

研究一种新型自由电子激光谐振腔结构.采用双曲面-抛物面非球面镜组合的扩束系统,使振荡光束在腔内口径扩大6倍.提高了反射膜层抗激光破坏能力.本文讨论了扩束倍数、非球面参量、谐振腔长度和掠射光斑尺寸等参量对光学系统像差的影响.     

多程放大腔镜准直研究

针对高功率激光装置对多程放大器腔镜准直的要求,利用小孔的像传递和光路自动准直的原理,设计出一套创新的腔镜准直调整方法,并且在SG-Ⅲ原型装置4程放大模拟实验平台上进行了实验验证。实验结果表明：自动准直系统能够在15min之内顺利完成主放大级系统的光路调整,光束近场调整精度值小于近场光斑直径的0.5%,光束远场调整精度小于0.3"。     

环形腔振动敏感度的研究

为了降低环形腔的环境振动敏感度,设计了一个四柱支撑环形腔。利用有限元数值模拟的方法,通过改变支柱的支撑位置和支柱直径,对环形腔进行数值模拟,得到了环形腔光程变化量随各参数变化的关系曲线。结果表明,通过选择适当的支撑位置和支柱直径,可以使得光程变化量趋近零,光程对振动不敏感。该方法对于高稳定环形腔的设计具有重要的指导意义。     

A mode-locked dye laser pumped by a xenon ion laser

Passive mode-locking of a rhodamine 6G dye laser has been achieved, using a pulsed xenon ion laser as a pumping source. A pulse width of 5 ps and a peak power of 4 kW have been obtained. Thermal problems were encountered, which adversely affected the operation of the dye laser. Work is in progress to improve these results.     

激光陀螺中背向散射的研究

为了研究谐振腔形状变化对激光陀螺中背向散射的影响,基于矢量叠加理论,分析了激光陀螺背向散射源及其对总的背向散射的影响.根据背向散射对顺逆时针光的耦合作用,推导出了总的背向散射系数与顺逆时针旋转光光强的关系式.基于这一关系,设计实验,通过施加电压使谐振腔反射镜到不同位置来改变光腔形状变化,同时测量光强交流量的振幅,得到了总的背向散射系数的变化曲线.通过与仿真结果对比,验证了背向散射的矢量叠加理论.