Xe Laser Research Articles

Characteristics of a unipolar corona discharge in active media of high-pressure atomic Ar, Kr, and Xe lasers

A study was made of the characteristics of a negative corona discharge with a continuous power supply in a point — plane electrode system, ignited at pressures of 50 — 350 kPa in He : R=100 : 1 ( R=Ar, Kr, or Xe) mixtures typical of active media of high-pressure discharge R* lasers. This discharge was found to be highly homogeneous during its steady stage and the specific pump power deposited in the plasma exceeded 1 W cm-3, which could be used in cw high-pressure discharge R* lasers.

Compact Ar–Xe Discharge Laser with Surface Multichannel Arc Ultraviolet Preionizer

Highly efficient, compact Ar–Xe lasers preionized using surface multichannel arc (SMA) ultraviolet (UV) radiation have been successfully developed to improve overall efficiency. We present that the overall efficiency can be enhanced by decreasing the specific input energy. When the specific input energy was 2.7 J/ l, an overall efficiency of 2.5% was achieved. The saturation parameter and the small-signal gain are estimated by fitting Rigrod's equation to the results of laser output power versus reflectivity of the output coupler. The kinetics of laser oscillation were considered in terms of the temporal laser intensity of the individual oscillation lines during multioscillation.

Laser patterning of thin-film electrochemical gas sensors

We have patterned a CO2 thin film electrochemical sensor using Xe laser ablation of Pt, Nasicon and Na2CO3 thin films. A thin metallic absorbing layer on Nasicon is used to achieve reproducible ablation of the ionic conductor with no piercing of the buried Pt electrode. Processing conditions are 10 J/cm2 pulses with a scanning velocity of 500 μm/s for Pt and 6.3 J/cm2 pulses with a scanning velocity of 100 μm/s for Nasicon. Nasicon is ablated in the form of flakes suggesting an ablation in the solid phase. Fabrication of an integrated heating element and a micro-thermometer by laser ablation is also presented.

Spectral investigation of cw rf-pumped atomic Xe laser with a slab geometry

A radiofrequency excited atomic Xe slab laser with an active volume of 2 × 10 × 300 mm3 using a quartz envelope containing the laser-gas mixture shows a stable cw performance with an output power of almost 1 W. The free-running system oscillates, depending on gas composition and density, on several lines between 1.73 and 3.51 μm. Line competition phenomena are observed. Single-line oscillation yields more than 500 mW.

High power continuous wave atomic Xe laser with radio frequency excitation

Radio frequency discharges in Ar/He/Xe gas mixtures have been studied in the range 5–150 MHz, and the importance of the ion sheaths in Xe laser excitation has been recognized. The discharge data have been used to improve the cw Xe laser performance, and efficiencies up to 0.8% observed. Area scaling in the slab geometry has been studied for α discharge excitation at 49 MHz, and multimode cw laser power up to 5.5 W has been observed. High quality beams have been produced at 4.9 W using a hybrid waveguide/unstable resonator.

Three-electrode discharge laser with a middle control electrode

A three-electrode discharge laser was developed. The discharge is ignited by the application of a high-voltage pulse to the middle control electrode. A storage capacitor for the main discharge is connected directly to the other two electrodes. The examples of excimer XeCl and KrF lasers, and also of an Ar—Xe laser, are used to show that such excitation of the active medium can reduce by tens of times the load on the switches in the power supply system.

Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab geometry

Near-infrared atomic Xe laser lines have been generated from an Ar:He:Xe laser gas mixture excited by a radio frequency (rf) discharge in a slab geometry. A maximum continuous wave (cw) output power of 1.5 W (270 W/l) was obtained at an rf frequency of 125 MHz from a gas mixture containing Ar:He:Xe (50:49:1) at a total gas pressure of 90 Torr.

IR recombination lasers

The present study contributes to a better understanding of the atomic Xe laser as a powerful IR source. Several important phenomena like the dependence of both the observed optimized input power and maximum output power on the square of the gas density and also the constant fractional ionization are reported and verified theoretically. The insight in the kinetics of this system has also lead to the realization of small-size continuous systems with output powers in the range of watts. The results of the present study can be used to predict the performance of the atomic Xe laser under different operating conditions.

Long pulse 250 keV electron gun for high-pressure gas lasers

The design and performance of a secondary emission electron gun with a wire ionized plasma as an ion source is discussed. An electron beam current density of up to 100 mA/cm2 is obtained over an area of 55×5 cm2 at a cathode voltage of 250 kV in pulses with a duration of about 20 μs. The current distribution over the beam area is uniform to better than 25%. The achieved combination of pulse duration, beam current, and electron energy is attractive to excite high-pressure gas laser media. Preliminary results with the utilization of the gun in an electron beam sustained discharge excited atomic Xe laser show an output energy of 1 J/ℓ at a wavelength of λ=1.73 μm.

A reasonably practical XUV laser for applications

We describe a laboratory-scale 109 nm Xe Auger laser pumped by an all-commercial high-repetition-rate Nd:YAG laser system. The Xe laser provides pulse energies up to 1 /spl mu/J, and an average flux of 3/spl times/10/sup 12/ photons/s at 11.5 eV. Measurements of the gain, output energy, and output beam shape are reported, along with an investigation of the time dependence of the gain. >

Investigation of lasing on Cd+, Zn+, Xe, and Ne transitions excited by a beam of nanosecond electrons

We have thus presented here experimental results of an investigation of lasing in mixtures of Cd and Zn metal vapors with helium, and of the influence of heating the mixture on the properties of the emission of Xe and Ne lasers excited by relativistic nanosecond electron beams. We have determined the optimal ranges of the active-medium temperature and of the buffer gas pressure for lasing on transitions of Cd+ and Zn+. The maximum output lasing power obtained by excitation by nanosecond electron beams were respectively 200 W, 400 W (6 kW/liter), 10 W, and 75 W for excitation by nanosecond pulses with 442 nm, 533 and 538 nm, 325 nm, and 610 nm, respectively. We have shown that the change of the output power of an Xe laser due to heating of its active medium is due mainly to mixing of the gas-mixture components and to the lower rate of the upper-level population on account of dissociation of the ArXe+ ions by collisions with the buffer-gas atoms.

New analysis for the assignment of UV-visible ionic Xe laser lines

Visible and UV laser emissions from a highly ionized pulsed Xe plasma were studied in relation to the ionic assignment of the laser lines. Time-resolved spectroscopy and intensity versus pressure analysis were used to determine the ionic origin of the studied lines. The results of both methods show good agreement, and the joint coincidence is used as a criterion for ionic classification, thus imposing a stringent condition for the assignment of the lines and enhancing its reliability. The disagreement between some of our assignments and those from other authors are discussed on the basis of the results of our systematic analysis of more than 200 spontaneous lines in the region of interest.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New continuous wave infrared Ar-Xe laser at intermediate gas pressures pumped by a transverse radio frequency discharge

An atomic Xe laser with a transverse rf excitation has been operated in a cw mode in the intermediate pressure regime. The laser output spectrum consisted of 5 Xe lines with wavelengths of 2.03, 2.63, 2.65, 3.37, and 3.51 μm. The unoptimized total output power of 330 mW was obtained for a gas mixture Ar:He:Xe=59:40:1 at a pressure of 85 Torr and a rf input power of 150 W and excitation frequency of 121 MHz.

Dynamics of the gain and generation of an Ar–Xe laser pumped by an electron beam

The time evolution of the small-signal gain and the development of generation on various spectral components of a laser operating on IR transitions of the Xe atom have been studied. The high-pressure Ar–Xe mixture was pumped by a beam of fast electrons with an electron current density ∼ 1.5 A/cm2. Experimental data obtained for Ar:Xe ratios from 19:1 to 1000:1 are used to calculate the collisional half-widths Δλ of working transitions with wavelengths λ = 1.73, 2.03, 2.63, and 3,37 μm. The half-width of the line with λ = 2.65 μm is calculated.

Electron-beam-pumped laser utilizing mixtures of Xe, Kr, and Ar with two-component buffer gases

Investigations were made of high-pressure lasers emitting due to infrared transitions of Xe, Kr, and Ar atoms pumped by an electron beam of current density j = 1.7 A/cm2 and using two-component buffer gas mixtures. Energy and spectral characteristics were obtained for different active mixtures. A record energy of Q2.03 = 9 J was achieved at a wavelength of λ = 2.03 μ in an He–Ar–Xe laser, with an efficiency of η2.03 = 1.1%.

Influence of the pump power on the spectral and time characteristics of an Ar–Xe laser

An investigation was made of the spectral and time characteristics of electron-beam-pumped and electron-beam-controlled Ar–Xe lasers operating in the pressure range p = 1–3 atm at electron current densities of j = 10–500 mA/cm2. Irrespective of the pumping method, the pumping rate was shown to be the principal factor determining the spectral composition of the output radiation. A physical efficiency of 3% was achieved in the case of an Ar:Xe = 299:1 mixture at a pressure of p = 1.5 atm pumped by electron beam pulses of current density j = 500 mA/cm2.

Intrinsic efficiency and critical power deposition in the e-beam sustained Ar:Xe Laser

Experimental investigations on an e-beam sustained near infrared Ar:Xe laser have been carried out to determine the intrinsic efficiency at optimized conditions. A parametric study at different sustainer currents reveals a maximum output energy depending on current density. Up to 8 bar the optimized laser output power per unit volume increases linearly with 1.1MW/1 bar. Intrinsic efficiencies of up to about 8% are feasible.

High-pressure Ar–Xe laser pumped by a self-sustained volume discharge

An investigation was made of the characteristics of a pulsed high-pressure Ar–Xe laser pumped by a self-sustained volume discharge. An output energy of 0.43 J and a specific output energy of 0.75 J · liter − 1 · atm − 1 were obtained. For the first time, an increase in the laser efficiency was observed when the interelectrode separation was increased.

Microwave response of YBaCuO thin-film Dayem bridges

1-μm-wide Dayem bridges were patterned with a pulsed Xe laser in c-axis-oriented YBaCuO films prepared according to the BaF2 method. The microbridges have a critical current density of 2×106 A/cm2 at 77 K, which is typical for an epitaxial film without grain boundaries. When microwave radiation in the centimeter wavelength range is applied, we observe current steps in the current-voltage characteristic up to 72 K. The dependence of these steps on microwave power is compared with the model of Golovashkin and Lykov {Zh. Eksp. Teor. Fiz. 74, 214 (1978) [Sov. Phys. JETP 47, 110 (1978)]}; we find that the step amplitude is smaller than predicted.

Spectral and bandwidth characteristics of a high-pressure Xe laser in a several kilogauss field

A technique based on the Zeeman effect has been developed for determining the gain bandwidth of the 1.73- mu m laser line of the high-pressure atomic xenon laser. A bandwidth in the range of 0.14 to 0.37 cm/sup -1/ has been determined by this method. Lasing bandwidths for the 1.73-, 2.03, 2.63, and 2.65- mu m lines have also been determined for pump rates in the range 0.3 to 1.8 kW/cm/sup 3/. The effect of the magnetic field on the spectral characteristics of these lines is also given. >