The stability of the active medium of RF-exited CO2 lasers with gold as catalyst

Using mass-spectrometric investigations the gas composition of the active medium of sealed-off cw RF-excited CO₂ waveguide lasers have been studied. It has been found that a low degree of CO₂ dissociation and a laser power improvement can be achieved by means of a gold catalyst in the laser discharge volume. The conditions for long operational lifetimes of these lasers are described. Received: 21 December 1999 / Revised version: 1 May 2000 / Published online: 6 September 2000     

The development of turbulence in the active medium of a fast-flow gas-discharge laser

The effect of pump nonequilibrium on the heat generation and the parameters of turbulent flow in the active medium of a fast-flow gas-discharge laser is studied. It is shown that the amplitudes of the turbulent pulsations of the density and refractive index of the active medium depend on the pump method and the degree of saturation by laser radiation and grow with the pump level. Criteria for estimating the effect of turbulence on the quality of the active medium are presented. A model is proposed that relates the build-up of the turbulent pulsations of the gas density and refraction to the heterogeneous heat release in the nonequilibrium active medium. The effect is determined by both the growth of the isobar local temperature pulsations and the ionization-overheating instability. In the case of dc-discharge pumping, the optical inhomogeneity of the active medium may substantially exceed that for the high-frequency discharge pumping. Original Text ? Astro, Ltd., 2006.     

Excitation dependence of the bending mode temperature in pulsed TE CO2 lasers

The observation of “steps” which appear in the gain immediately after excitation in pulsed TE CO₂ discharges is reported. It is shown that the measurement of the step size relative to the peak gain serves to determine the population of the lower laser level and thereby, the initial vibrational temperature (T₁) of the bending mode. This technique is applied to a study of T₁ as a function of the discharge input energy.     

Measurement of rotational temperature in CO2 waveguide laser medium

A small-signal gain in CO₂ waveguide laser medium has been measured on rotational-vibrational transitions in the P-branch of the (0, 0, 1)-(0, 2⁰, 0) band. It has been found that the rotational temperature is well defined in the waveguide laser system where high excitation power is injected and a large amount of energy is flowing through vibrational, rotational, and translational degrees of freedom. The rotational temperature is slightly higher than the translational temperature.     

Multi-crystalline silicon as active medium for terahertz intracenter lasers

Stimulated emission at terahertz frequencies has been obtained from multi-crystalline silicon doped by phosphor under optical excitation by a mid-infrared laser. The silicon samples consist of grains with a characteristic size distribution in the range from 50 to 500 μm. The maximum operation temperature of the laser made from multi-crystalline silicon is 6 K less than that of monocrystalline lasers and the maximum output power is three times less while its laser threshold is only slightly higher and the emission frequency is the same. These effects are attributed to internal strain and enhanced phonon scattering induced by grain boundaries.     

Waveguide CO2 lasers on sequence-band transitions

Two waveguide CO₂ lasers, a quartz waveguide and an alumina waveguide, have been studied on the 00°2–[10°l,02°1]_I,II sequence bands. The use of an intra-cavity hot CO₂ cell, which is a part of the waveguide, suppresses the regular-band transitions. The quartz waveguide laser has a total of 58 lines lasing on both the 9.4 µm and 10.4 µ,m sequence bands. The alumina waveguide laser has 36 lines lasing on the 10.4 µm sequence band and twice the output power of the quartz waveguide laser, whereas lasing on the 9.4 µm sequence band is difficult. The lasers can be operated on the selected single line without line jumping problem. The frequency tuning range of the strong lines is limited by the free spectral range of the cavity.     

High-pressure pulsed CO2 lasers

This paper presents a large body of data allowing one to determine the energy, time, and spectral characteristics of high-pressure pulsed CO₂ lasers over wide ranges of parameters. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 19–28, April, 2000.     

On the opto-voltaic measurements in CO and CO2 lasers

We observed and compared the opto-voltaic signals in CO and CO₂ lasers. The signals are obtained capacitively from the water cooling jacket as a low voltage source not influencing the current circuit. We observed from measurement that the output power and the so-called optovoltaic input power have a distinct relationship depending on laser current and cavity parameters. It will be shown that opto-voltaic detection is a very sensitive method especially for CO lasers.     

Plasma-chemical processes in the active medium of a CO laser

The concentrations of plasma-chemical products (C, O, CO₂, C₂, and C₃O₂) were measured under conditions typical of the active medium of an electrical discharge CO laser. The dependence of the concentration of C₃O₂ molecules on the experimental conditions was studied. A reaction scheme responsible for the concentration of C₃O₂ molecules formed in the discharge was proposed.     

Bismuth-doped-glass optical fibers--a new active medium for lasers and amplifiers

Optical fibers with bismuth-doped silicate and germanate glass cores were fabricated by the modified chemical vapor deposition technique (solution and vapor-phase Bi incorporation). The fibers revealed an efficient luminescence with a maximum in the 1050-1200 nm spectral range, FWHM up to 200 nm, and a lifetime of the order of 1 ms.