High energy density NH3 laser using an unstable resonator CO2 laser pump

The design and operation of a novel optically pumped molecular gas laser cell, which uses geometrical coupling and is compatible with high energy unstable resonator CO₂ laser pump beams, is described. The attainment of high energy output densities (>0.5J$\text{e}$?1>^-1) from the 12.08 μm and 12.81 μm NH₃ laser transitions using this pumping arrangement is reported.     

Studies of a high performance TE CO2 laser using additives

It has been observed that significant increases (～ 40%) in both the small-signal gain and laser efficiency occur when small, carefully controlled quantities of tripropylamine are added to the gas mixture of a TE CO₂ laser. The results obtained are compared with the predictions of a detailed molecular kinetics model and are shown to be consistent with the proposal that doping helps to maintain the discharge uniformity at high energy loadings. With the small TE laser employed, the use of tripropylamine has enabled laser energy densities of ～ 47J 1^-1 atm^-1 to be achieved at a discharge efficiency of ～ 10%     

The application of an unstable resonator to a high-pressure CW CO2 laser

Unstable resonators provide high quality beams of high output power needed for material processing. We have developed a CO₂ laser of over 5 kW for material processing with an unstable resonator of positive confocal configuration under high-pressure, sealed condition. High quality beams with high extraction efficiency of the power were obtained and deep pentration was attained in welding tests.     

Studies of a TEA CO2 laser with a cylindrical mirror unstable resonator

We describe the results of a study of a TEA CO₂ laser using a strip cylindrical unstable resonator which produces an output beam with suitable characteristics for producing a high quality line focus. Using this technique an irradiance of ?10⁹W cm^-2 over a 5 cm long line focus has been achieved.     

Very high power line-selective CO2 laser with (line-selective) unstable resonator

By replacing the conventional (non line-selective) unstable resonator, we succeeded in developing the very high power line-selective (line-tunable) CO₂ laser as a pumping source for high power molecular gas (e.g.NH₃) lasers in the infrared and far-infrared regions.The experiments were performed by using the very high power CO₂ laser (4A unit of Lekko VIII) at The Institute of Laser Engineering, Osaka University.The output power of 9R(30)9.22µ m line from the developed CO₂ laser, for instance, exceeded 0.5GW/pulse (50J/pulse with pulse width of 100nsec).     

Single mode operation of a continuously tunable TE CO2 laser using a three mirror resonator

An analysis and experimental results for spectral narrowing and mode-control of a continuously tunable TE CO₂ laser using a three mirror resonator is reported. Single mode operation of a 10 atmosphere device has been obtained with an estimated linewidth of ?0.5 GHz.     

Single transverse mode operation of a pulsed volume excited atmospheric pressure CO2 laser using an unstable resonator

The operation of a volume excited TEA CO₂ laser using an unstable resonator configuration is described. Considerable improvement over conventional single mode operation is achieved. The theoretical and experimental far field patterns are compared.     

Single mode oscillation of TEA CO2 laser with an interference resonator

An effective single-longitudinal mode (SLM) pulse TEA CO₂ laser operation was demonstrated using a Michelson’s type resonator with a tilting Fabry-Perot etalon. A modified numerical model of the interference resonator was investigated for designing the laser. The experimentally measured values were found to have good agreement with the numerical model. A pulse width of about 90 ns and the maximum pulse energy of about 300 mJ were achieved at 10.59 μm in SLM and TEM₀₀ mode. The reliability of producing SLM pulses was 100% and there was no damage on the etalon. By turning the interference resonator, the SLM output was tuned 44 lines of the CO₂ spectrum.     

A long-pulse TE CO2 laser with a negative-branch unstable resonator

Summary A long-pulse (>3 μs) CO₂ laser has been built using a negative-branch, frequency-selective, unstable resonator. The results obtained with this device are shown. The authors of this paper have agreed to not receive the proofs for correction.     

Mathematical modeling of TE CO2 laser with SF6 as a saturable absorber

A mathematical model describing the dynamic emission of a single mode TE CO₂ laser with saturable absorber has been adapted. A six-temperature model has been used to describe the amplifying medium, while a four-coupled energy level is used to describe the selective absorbing medium. The suggested mathematical model allows the investigation of the effects of the intracavity absorber on the mode characteristics of the TE CO₂ laser and, moreover, the study of the effect of the laser input parameters on the output laser pulse. The model simulates the passive Q-switch in both low- and high-pressure cases in the absorbing medium.

In addition, numerical solutions of a non-linear rate equation system of the suggested model are quantitatively discussed. The solutions describe the photon number density, the population inversion and the energy transfer processes of amplifying and absorbing media.     

The amplified spontaneous emission in TE CO2 laser with a half-cavity

The new structure with a half-cavity in TE CO₂ laser is described. In this device, a total of nearly 50 lines from transitions in P and R branches of the 9.6 and 10.6 μm bands is observed. The energy, the spot pattern and pulse width of those lines are tested.     

Infrared and far-infrared laser emissions from a TE CO2 laser pumped NH3 gas

In this paper, infrared (IR) and far-infrared (FIR) laser emissions from a TE CO₂ laser pumped NH₃ gas are reported. 8 IR laser emissions near the wavelength of 12 μm were observed by using 4 different CO₂ laser lines for the pumping. 3 IR laser emissions in P-branch of vibrational-rotational band (ν₂ → G) oscillated simultaneously in two pumping cases, i.e. pumping with the R(30) or R(16) line of 9.4 μm band from the CO₂ laser. 26 FIR laser emissions (26.45 μm ～ 281.0 μm) were observed by using 12 different CO₂ laser lines, and the 10 FIR emissions of them may be new laser emissions as far as we know.     

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     

High repetition-rate and quasi-cw operation of a waveguide CO2 TE laser

We report operation of a waveguide CO₂ TE laser at excitation pulse repetition frequencies as high as 40 kHz. Quasi-continuous laser output was obtained yielding an average output power of 1.5 W from an active volume of 0.1 cc. Details of laser construction and excitation circuitry are given.     

Configuration analysis of the resonator in a double-pulse TEA CO2 laser

This paper describes the resonator configuration of a double-pulse TEA CO₂ laser, and discusses how to obtain single-mode operation in that configuration.     

Optically pumped NH3 laser using a continuously tunable CO2 laser

The use of a continuously tunable CO₂ laser to optically pump the NH₃ laser via previously inaccessible absorption lines is described. Efficient laser action has thus been achieved in the 11–13 μm region on transitions formerly only obtained in buffered mixtures.     

Real time linewidth measurement of a continuously tunable multiatmosphere TE CO2 laser

Frequency upconversion as a means of investigating the spectral characteristics of continuously tunable multiatmosphere TE CO₂ lasers has been demonstrated. Phase matched mixing in proustite of 10 μm laser radiation and the output of a single-mode Nd:YAG laser has permitted Fabry-Pérot interferograms, at the 0.96 μm sum frequency, to be recorded with the aid of a conventional image converter tube.     

管状预电离可调谐TEA CO2激光器

研制了一种新型的预电离结构——管状预电离器,并将其应用于可调谐TEA CO2激光器。利用光栅选线方案,采用光栅谐振腔,实现了激光的调谐输出。在输出耦合率为50%、气压为40 kPa的条件下,10P(20),10R(20),9P(20),9R(20)四条谱线获得的最高电光转换效率,分别为9.5%,9.7%,9.8%,9.8%。实现了激光器的高重复频率可调谐输出运转,测量了上述4条谱线激光输出的脉冲能量及平均功率,在输出耦合率为50%、气压为30 kPa的条件下,重复频率最高可达190 Hz, 此时的10P(20),10R(20),9P(20),9R(20)四线的平均功率分别为322,321,340,338 W。     

Cutting and welding using a CO2 laser

Of all the types of lasers now available, the CO₂ laser is particularly suitable for materials working. It has a very high efficiency (15–20%) and a high out-put power (up to several kW). When the laser light is focused by means of a lens or a mirror, a c.w. power density of more than 10⁹ W cm^-2 can be attained. The laser need not be used in vacuum.

The CO₂ laser is a suitable cutting tool for numerous materials. These include metals such as titanium or steel; combustible materials such as paper, textiles and wood; and plastics. The CO₂ laser can also cut hard and brittle materials such as aluminum oxide and silicon carbide. If metals are cut in an oxidizing atmosphere, the cutting speed may be increased. The cutting width, however, is determined by the size of the laser spot. Another important field of application is the growth of single crystals.

Experiments are reported in which the CO₂ laser was used for welding steel, titanium, plastics, quartz, and glass. The advantages of the laser for this application are discussed. A comparative study of laser and electron beam techniques is included.