Absolute frequencies of CO2 laser transitions by multiplication of CO2 laser difference frequencies

Frequencies of CO₂ laser transitions have been compared to the Cs standard by a four-step frequency chain using difference-frequencies from five CO₂ isotope lasers. A tungsten-nickel diode generates the differences and their harmonics. Measurement of the 10.71 μm R(6) transition of ¹³C¹⁸O₂ is described. The absolute frequency was found to be 27 979 469.512(65) MHz. Simultaneously, the four other CO₂ frequencies in the chain were also determined.     

Far infrared stimulated emissions from CO2 laser excited dichloromethane

Six new far-infrared laser frequencies have been obtained in CO₂-laser excited dichloromethane. Competing transitions have enabled assignments to be made to the v₇ band.     

Far infrared emissions in NH3 using “forbidden” transitions pumped by a CO2 laser

In this paper it is shown that the use of Stark effect on ammonia gives the possibility to use pump transitions which are forbidden ones in the absence of an electric field. New far infrared emission lines are reported which cannot be obtained using the usual allowed pump transitions.     

Far infrared reflectivity spectra of a KH2PO4 single crystal

Conclusion The experimental results presented in this paper show that two heavily damped modes, due to proton tunneling, are active in the two phases of KDP: the well-known soft mode which attains a hard-core frequency at the transition temperature and a low frequency mode polarized in a direction perpendicular to the c axis. These modes are responsible for the temperature variation of the low frequency dielectric permittivity in the two crystallographic directions. Due to the size of the samples we do not obtain a single domain crystal, and it was impossible to distinguish the B₁ and B₂ modes. The 200–300 cm^–1 spectral range is very sensitive to the orientation of the incident wave, and certainly corresponds to the hydrogen bonds vibrations.     

Tunable terahertz generation from one CO2 laser in a GaSe crystal

Coherent terahertz pulses have been generated at a range of 236.3-1104.5 μm (0.27-1.3 THz) by one CO₂ laser with dual-wavelength output based on collinearly phase-matched different frequency generation (DFG) in a GaSe crystal. This source has the advantages of compact and simplicity for tuning. The output power of the THz pulse and phase-matching conditions were investigated. The maximum single pulse energy of 11 nJ was generated at a frequency of 1.23 THz (243.6 μm), corresponding to a peak output power 182 mW.     

Comparative investigation of long-wave infrared generation based on ZnGeP2 and CdSe optical parametric oscillators

Long-wave infrared (IR) generation based on type-II (o→e+o) phase matching ZnGeP₂ (ZGP) and CdSe optical parametric oscillators (OPOs) pumped by a 2.05 μm Tm,Ho:GdVO₄ laser is reported. The comparisons of the birefringent walk-off effect and the oscillation threshold between ZGP and CdSe OPOs are performed theoretically and experimentally. For the ZGP OPO, up to 419 mW output at 8.04 μm is obtained at the 8 kHz pump pulse repetition frequency (PRF) with a slope efficiency of 7.6%. This ZGP OPO can be continuously tuned from 7.8 to 8.5 μm. For the CdSe OPO, we demonstrate a 64 mW output at 8.9 μm with a single crystal 28 mm in length.     

Far infrared laser frequencies of CH3OD and N2H4

The frequencies of 26 laser lines with wavelengths between 57 and 534 m have been measured in the optically pumped laser gases CH₃OD and N₂H₄. A pair of stabilized cw 12_{CO 2} lasers was used as a frequency standard for the heterodyne frequency measurements. Seven of the 26 lines are new.     

Slab CO2 lasers excited by switching power

In this paper we present a new discharge technique to excite slab CO₂ lasers. A uniform stable glow discharge has been obtained in a volume of 3 × 30 × 446 mm³. Output power is 10 W, and a gain of 0.26% cm⁻¹ has been obtained.     

Mode-locked pulses in multi-atmosphere CO2 lasers

The present paper deals with AM mode locking of multiatmosphere CO₂ lasers. We measure the effective linewidth in the laser mixtures and deduce from these data the pulse width. The method is based on determining the maximum frequency shift from the synchronized frequency. The advantage of this method is that the results are not influenced by time constant of detector and display. The results were verified by direct measurements of the pulse widths in mixtures up till three atmospheres. The pulse widths and effective line widths of the P(20) transition are determined for the usual CO₂ laser mixture up till 6 atm. We observe that helium has a large effect on the pulse width. The width decreases with increasing helium percentage at all pressures investigated. We suggest that this has to do with the overlap of a sequence-band transition and that the effect of sequence bands depend ion the helium percentage.     

Polarization synchronization in quasi-isotropic CO2 lasers

We present experimental evidence of the in-phase and out-phase synchronization of the polarization in two coupled quasi-isotropic CO₂ lasers. We also show, by means of numerical simulations, how it is possible to retrieve message encoded in the polarization of the master laser from the observation of the slave laser alone, due to the synchronization.     

One-dimensional modelling of TEA CO2 lasers

One-dimensional modelling was applied to a TEA CO₂ laser whose discharge volume was divided into multiple narrow channels. Each of these channels was regarded as a separate laser channel in which a circuit-coupled kinetic model was employed to compute its discharge formation, and a rate-equation model was used to predict its laser output. Such a one-dimensional model could be employed to study the spatial variation in the transverse discharge—due mainly to a one-sided ultraviolet-preionization and the electrode contour—and its effects on the laser output. Reasonably good agreement was obtained between the one-dimensional model and the experiment, which employed a pair of Ernst profile electrodes.     

Spatial-dependent simulation of TEA CO2 lasers

We have developed a 1-D spatially-dependent model and simulation code to study the dynamics of TEA CO₂ lasers. In this paper we will discuss the motivation for developing the model and present the simulation details. We have compared and verified the simulation results with the previous 0-D model, and with the measurements of a TEA CO₂ laser. With spatial resolution, the 1-D simulation is in better agreement with experimental results compared with the existing 0-D model.     

The role of CO in CO2 lasers

The population inversion in a CO₂-He glow discharge has been calculated, taking into account CO produced by dissociation in the discharge. The calculation was based on experimentally determined electron energy distributions and the measured effective relaxation constant of CO₂ (001). It is shown that the population inversion is negligible in the absence of CO.     

A new paramagnetic center in ZnGeP2

An unusual E.P.R. signal is observed in as grown samples of ZnGeP₂. The defect concentration is $\text{?0.5 × 10}{}^{\mathrm{?5}}\text{(}\text{2 × 10}{}^{17}\text{cm}{}^3\text{)}$. The g-values are g_ζζ = 2.04, g_νν = 2.08 and g_ξξ = 2.00. The observed splittings are attributed to hyperfine interaction with two phosphorus ions. The hyperfine tensor, A, is extraordinarily anisotropic.     

RF generator for compact CO2 waveguide lasers

This letter reports the fabrication and testing of a compact Radio Frequency Generator (Oscillator-Amplifier) for its integration in a CO₂ waveguide laser. The circuit uses a common source MOSFET transistor that has been modified for self-sustained oscillations impedance-matched to 50 Ω. RF power is supplied to the laser resonant cavity made of a ceramic-metal slab which is placed between a negative branch unstable optical resonator.     

脉冲CO2激光器的多频动力学模型

建立了适用于各种气压下(20×133—20×10⁵ Pa)的脉冲CO₂激光器的六温度多频动力学模型，该模型考虑了增益谱线重叠效应，序列带、热带的影响，以及非洛伦兹线型效应.对模型进行数值求解可以预言和解释不同气压下的脉冲CO₂激光器的输出特性，有助于评价不同的抽运设计和研究可调谐特性，为设计脉冲CO₂激光系统提供理论支持. 关键词： 2激光器')" href="#">CO₂激光器 激光动力学 六温度模型 增益谱线重叠     

A new design for rf-excited CO2 lasers

In this paper a new four-pole electrode design for radiofrequency excited CO₂ lasers is described. Here, the two functions of the discharge tube, rf-excitation and dischare cooling can be optimized separataly. With a symmetric rf excitation technique electromagnstic interference is also minimized. A prototype laser with 50 cm cavity length produced about 2.5 W laser output power at 5% efficiency.     

Styrofoam calorimeter for high energy CO2 lasers

A simple calorimeter that has been used to measure pulse energy and energy distribution of a pulsed gas-dynamic laser is described. The pulses had an energy density 10 J cm^-2 and width 0.1 s. Energy is determined from the volume of styrofoam melted by the pulse. Results showing the linearity of the method are given.     

Mathematical modeling of tunable TEA CO2 lasers

A mathematical model, based on the Landau–Teller equations of six-temperature model for the CO₂–N₂–He–CO system, to describe the process of dynamic emission in tunable TEA CO₂ lasers is introduced. In this model, the Landau–Teller equations are rewritten with regard to fine longitudinal mode frequencies in the laser resonator. These revised equations can be utilized to estimate the laser output spectra as well as other laser output pulse parameters. Examples are given to show the modeling results of non-tunable, grating tuned or injection-locking TEA CO₂ lasers.     

Transverse mode formation time in pulsed CO2 lasers

Transverse mode formation dynamics were analyzed using a low-magnification (M = 1.32) positive-branch confocal unstable resonator in a high-energy pulsed CO₂ laser. The temporal behavior of mode formation was experimentally examined by observation of far-field burn pattern changes. Experiments agree with geometrical and computational results.