Pulsed laser action of Pr:GdLiF4 at room temperature

We realized, to our knowledge for the first time, laser emission in Pr:GdLiF₄ at seven wavelengths: 522 nm, 545 nm, 604.5 nm, 607 nm, 639 nm, 697 nm, and 720 nm. The crystal was pumped with an excimer laser pumped dye laser at 468 nm. All laser experiments were carried out at room temperature. We also achieved pulsed room temperature laser oscillation of Pr:KYF₄ at 642.5 nm pumped at 465 nm wavelength.     

CO laser stabilization using the optogalvanic Lamb-dip

Frequency stabilization of the CO laser using a CO lamb-dip is achieved in the range from 5.0–6.3 m. The CO saturation signal is obtained from a low-pressure discharge in absorption and is detected using optogalvanic, detection. The frequency stability and reproducibility has been verified to be better than 100 kHz; this is an improvement of more than one order of magnitude compared with locking techniques using CO laser gain profiles.Alexander von Humboldt Awardee from National Bureau of Standards, Boulder, Colorado, USA     

Development of a new CW single-line CO laser on thev′=1→v″=0 band

CW single-line laser oscillation on theP(7) toP(15) transitions in the fundamental band of CO is reported. Laser operation was obtained with a liquid-nitrogen-cooled dc electrical discharge flow system using a mixture of He, N₂, air, and CO. The parameters important for the CO fundamental band laser oscillation are discussed.     

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.     

Diode-end-pumped linear-polarized single-frequency Tm:YAG laser at room temperature

By using two solid uncoated etalons, we present a diode-pumped linear-polarized single-frequency Tm:YAG laser operating at 2 μm. Placing one 0.1 mm F-P etalon at nearly Brewster angle in the cavity, the linear-polarization laser is achieved. The other 1 mm F-P etalon was turned in the range of very small angle, single-longitudinal-mode (SLM) could be obtained. The maximum output power of linear-polarized single-frequency laser of 60 mW is achieved at the wavelength of 2013 nm. The degree of the polarization is over 30 dB. Long-term frequency stability was also investigated, with the results of wavelength fluctuation about 2.55 × 10⁻¹³ m within 3 min and frequency change about 18.86 MHz, corresponding to a frequency stability of 1.27 × 10⁻⁷.     

Further investigations on ir pumping of CH3OD and CD3OD by a cw CO2 laser

Respectively, 41 and 36 new cw far-infrared lasing lines have been observed using a waveguide resonator in CH₃OD and CD₃OD pumped by a low-pressure CO₂ laser emitting in the 9.4, 10.4 m regular bands and in the 10.8 m hot band. The wavelength range was 46.6 m–1.67 mm in CH₃OD and 53.6 m–1 mm in CD₃OD.     

Improved gain for the Ar 2 * excimer laser at 126 nm

Argon was excited by intense electron beam pumping. The optical gain obtainable in Ar ₂ ^2* at 126 nm was investigated as a function of gas pressure and pumping density. The gas pressure necessary to achieve a gain of 10%/cm is reduced from 3.2 to 1.0 MPa if the gas is cooled at 170 K. The effect is partly due to reduced absorption by the removal of impurities. The results allow one a new approach to construct high-power lasers in the vacuum ultraviolet below 150 nm.     

New strong CW FIR laser actions and assignments in COF2

Thirty one new cw far-infrared laser lines have been discovered in COF₂ optically pumped by a CO₂ laser and a N₂O laser, in a metallic waveguide resonator. This number appreciably increases the number of eighteen lines appearing in the literature. Moreover, some of the new lines show that intense far-infrared laser action might be obtained with an optimized cavity, as it was the case for some of the previously reported lines. Twenty-seven, amongst the thirty one new lines, have been fully identified.     

Comparison of pulsed and continuous operation of the Cu II laser

The peak output power of Cu II laser emission in the uv at 260 nm and in the ir at 780 nm was measured for different operating conditions in the pulsed and the cw mode. In contrast to the ir laser output the laser power in the uv is higher in the cw mode than in the quasi cw mode. This property depends on contaminations of the discharge gas.     

Saturation stabilization of the CO fundamental-band laser

We recently reported the extension of CO laser operation to a variety of single-line transitions in the fundamental band (v=1 0). Now saturation stabilization of these lines could be achieved using an intracavity absorption cell with CO at low pressure. A 3f-detection technique allowed reliable frequency locking on transitions from P(8) to P(14). A frequency stability of better than 10kHz was indicated. The frequency of the P(14) transition was measured in a heterodyne experiment to be 62, 546, 358.324 (50) MHz.     

The laser pulse from a rf waveguide CO2 laser

The behaviour of a rf-excited waveguide CO₂ laser in the pulse regime is studied experimentally. The specific time sections of the pulse have been defined and described in detail. The output pulse evolution versus input power, pressure of the laser mixture, output coupling, repetition frequency and pulse width has been investigated. The spectral content of the pulse has been analysed. A model explaining the effect of laser tuning during the pulse duration is given. The ultrahigh pulse (UHP), defined as the pulse for which the bulge effect occurs, is predicted. Received: 22 October 2002 / Revised version: 13 January 2003 / Published online: 26 March 2003 RID="*" ID="*"Corresponding author. Fax: +48-71/3203-189, E-mail: eda@zr.ita.pwr.wroc.pl     

Continuous-wave Ho:GdVO4 laser pumped by Tm-doped fiber laser with a fiber Bragg grating at room temperature

We reported the Ho:GdVO₄ laser pumped by Tm-doped laser with a fiber Bragg grating. 2.03 W continuous-wave Ho:GdVO₄ laser output power is obtained under 10.5 W incident pump power, with the optical-to-optical conversion efficiency and slope efficiency of 19.3% and 32.3%, respectively, at 7 °C. We can see that, the lower the temperature is, the better the laser output character is. The beam quality factor is M² ∼ 1.29 measured by the traveling knife-edge method.     

A single-mode KrF laser

Single-mode operation of a KrF laser oscillator has been achieved for the first time. The laser medium is pumped by an electron beam which allows excitation for a much longer duration than with discharge pumping. The long excitation time, together with the use of a short oscillator cavity with a low single-pass gain, allows many roundtrips before saturation is reached. This makes line-narrowing easier and single-mode operation has been achieved using only two intracavity etalons.Technical Research Centre of Finland, Helsinki, Finland     

New far-infrared laser lines from CH3Cl and CH3Br optically pumped with a continuously tunable high pressure CO2 laser

In this paper we report on the detection of new far-infrared laser lines from CH₃Cl and CH₃Br optically pumped with a continuously tunable high pressure CO₂ laser. We found 80 new lines for CH₃Cl and 9 new lines for CH₃Br in the frequency region between 16 cm^–1 and 41 cm^–1, all due to stimulated Raman scattering. For the Raman gain regions bandwidths up to about 700 MHz were found. We also observed high intensity short far-infrared laser pulses of durations in the nanosecond regime.Permanent address: Physics Department, State Pedagogical University, SU-119435 Moscow, USSR     

Detailed simulation of recombination XUV laser experiments

The detailed simulation of recombination XUV laser experiments is described and the calculation of gain as measured by two different experimental techniques is discussed. It is shown that a reasonable comparison between simulation and experiment can only be obtained if the self-trapping of the Lyman line is neglected.     

Spectral structure of CuBr vapor laser lines

The atomic density, the buffer gas pressure, and the voltage dependence of the 510.6 nm laser line shape and its temporal evolution emitted from a Cu/CuBr vapor laser are measured. It is found that the monochromaticity of these laser lines can be improved greatly at a relative high buffer gas pressure. The temporal evolution of the line shape offers a stereoscopic view of a laser pulse. The sequence of appearance of the peaks of the line shape is governed by the intensity of the hyperfine component of the copper line.     

Subpicosecond UV pulse generation for a multiterawatt KrF laser

A 180-fs UV pulse has been generated based on a hybrid synchronously pumped mode-locked dye laser for a multiterawatt KrF laser system. The pulse width was measured by the single shot autocorrelation technique with the three-photon fluorescence of the XeF C-A transition. The pulse width broadening due to dispersive media was investigated. The results show that the observed pulse width broadening from 210 fs to 390 fs through the entire system is explained mostly by the linear dispersion of the optical elements for near-transform-limited input pulses.     

Selective optothermal detection of NO2 and H2O with a frequency-tuned CO waveguide laser

The results are reported of the CO-laser optothermal (OT) detection of impurity gases when their absorption spectra overlap with those of an interfering gas. The influence of the latter was avoided using low gas pressures corresponding to a maximum of the OT sensitivity. Frequency tuned in the 5.2–6.3 m wavelength range, ¹²C¹⁶O and ¹³C¹⁶O waveguide lasers were used. The fine frequency tuning at 490 MHz was achieved for 150 laser transitions of both molecules. The OT sensitivity was estimated by NO₂ detection in the presence of water vapor. The minimal detectable concentration proved to be 60 ppb at P _19–18(14) transition of a ¹²C¹⁶O laser for NO₂ and 75 ppb on P _12–11(13) transition of a ¹³C¹⁶O laser for H₂O.     

Characteristics of a wire preionized nitrogen laser with helium as buffer gas

The operation of a small N₂ laser using wire preionization and He as a buffer gas is discussed. The preionization is found to increase the output power and energy by 50% while the addition of helium can increase fourfold the output power.     

A copper vapour laser operating at room temperature

Laser action on the 5106 and 5782 Å lines of neutral copper has been achieved at temperatures from 20 to 140°C in the vapour of copper acetylacetonate, and at temperatures between 150 and 215°C in the vapour of copper nitrate. The peak output powers are compared with those obtained in the vapours of the copper halides CuCl, CuBr and CuI using the same longitudinal discharge operated in a double-pulse mode in low pressure argon. The highest peak power from copper acetylacetonate obtained to date is 5 kW at a temperature of 40°C. The optimum temperature for the nitrate is 180°C at which the peak output power is 20 kW. The halides can give pulses of 50 kW although the temperatures required are much higher. For the acetylacetonate and the nitrate it is necessary to purge the gas mixture of dissociation products by flowing the argon through the discharge tube. It is probable that the resulting reduction in copper density is partly responsible for the poorer performance observed to date with these vapours. Optimum argon pressures and delay times between the two pulses of discharge current were approximately the same for all the copper compounds tested.