V. S. Pazyuk

Repetitively pulsed chemical oxygen-iodine laser with a discharge generation of atomic iodine

Pulsed chemical oxygen-iodine laser with a discharge generation of atomic iodin is described. Having the output energy like that with photolysis iodine atoms generation such a laser exhibits higher plug-in efficiency. The efficiency value of 91% is reported. Pulse power of 100 kW was obtained which exceeds two orders of magnitude that for cw laser with the same chlorine flowrate. Repetitively pulsed operation is reported.

Experimental investigation of chemical oxygen-iodine laser

Results of an experimental investigation of a chemical oxygen-iodine laser (COIL) are presented. We determine the factors influencing the efficiency of a chemical singlet-oxygen generator (SOG) of the bubbler type operating on the chlorination of an alkaline solution of oxygen peroxide. We describe SOG constructions. A cw COIL with output power up to 400 W is developed on the basis of the investigated SOG. The feasibility of a modular construction of high-power COIL is demonstrated. A power-output level of 1 kW was achieved with a two-section laser. The feasibility is analyzed of COIL operation in a pulsed regime by pulsed bulk accrual of iodine atoms. We show that in this regime the laser can be operated without a low-temperature trap. An advantage of such a regime is also the possibility of controlling, in a wide range, the lasing pulse duration. A strong influence of molecular chlorine on the energy content of the active medium is observed when alkyliodides are used as iodine donors. The possibilities of using a pulsed COIL for controlled thermonuclear fusion are discussed.

A frequency-doubled pulsed chemical oxygen-iodine laser

The intracavity second-harmonic generation of pulsed chemical oxygen-iodine laser radiation was investigated. A pulsed chemical oxygen-iodine laser with a maximum output energy of 6.14 mJ was used. The second-harmonic output of 0.5 mJ was demonstrated using a lithium iodate crystal. The conversion efficiency of 8% was limited by intracavity losses. Numerical simulation predicts that a conversion efficiency of 75% can be obtained with 1% intracavity losses.

Spectral dynamics of a multimode Co:MgF2 laser with intracavity absorption

Spectral dynamics of a cw Co:MgF2 laser with intracavity absorption is recorded in the spectral range around 2 μm. Sensitivity to intracavity absorption corresponds to the absorption path length of 1200 km. New absorption lines of methane are detected.

Features of kinetic processes in the active medium of a pulsed chemical oxygen-iodine laser

ConclusionIt can be concluded from our experiments and calculations that the product CF3O2 of the interaction between the CF3 radical and the O2 molecule quenches the oxygen O2(1Δ) more strongly. At low chlorine admixture density in the singlet-oxygen stream this output energy of the oxygen-iodine laser with CF3I as the atomic iodine donor is lower compared with CH3I. The rate constant of quenching singlet oxygen by CF3O2 molecules is (3–5)·10−11 cm3·sec−1. It would be possible to decrease the influence of CF3O2 by adding to the initial O2*−O2−CF3I−Ar active mixture some other substance causing the CF3 radicals to enter in a chemical reaction with a shorter characteristic time than that for CF3O2 formation. Of course, neither the initial substance nor the reaction products should quench O2* noticeably. This role can be possibly assumed by the NO molecule.The influence of the chlorine additive on the output energy of a laser with CH3I and CF3I differs greatly. The choice of the chlorine donor must therefore be determined by the amount of this additive. CH3I is preferable if the chlorine is fully utilized in the singlet-oxygen laser, and CF3I in the opposite case.

Femtosecond compressed-nitrogen Raman laser

We have estimated the minimum laser pulse duration at which stimulated Raman scattering in gases is possible. Femtosecond Ti : sapphire laser pulses have been converted to the first Stokes in compressed nitrogen using double-pulse pumping of a gas-filled capillary tube by orthogonally polarised chirped pulses. We have obtained 980-nm Stokes pulses of 51 fs duration. The energy conversion efficiency was 12 % at a pulse repetition rate of 1 kHz and average laser output power of 2 W.

Direct detection of singlet oxygen O{sub 2}(a{sup 1} {Delta}{sub g}) by absorption at the a{sup 1} {Delta}{sub g} {yields} b{sup 1} {Sigma}{sub g}{sup +} transition using intracavity laser spectroscopy

The absorption spectrum of singlet oxygen O2(a1 Δg) is detected in a gas phase at the a1 Δg → b1 Σg+ transition by the method of intracavity laser spectroscopy using a broad-band Co : MgF2 laser emitting 200-μs pulses at a wavelength 1.91 μm. In the case of Doppler broadening of absorption lines at room temperature, the sensitivity of detection of O2 (a1 Δg) is ~ (2 — 5) × 1014 cm-3 . It is shown that the gas temperature can be calculated from the dependence of absorption cross sections for individual lines on the rotational quantum number.The absorption spectrum of singlet oxygen O{sub 2}(a{sup 1} {Delta}{sub g}) is detected in a gas phase at the a{sup 1} {Delta}{sub g} {yields} b{sup 1} {Sigma}{sub g}{sup +} transition by the method of intracavity laser spectroscopy using a broad-band Co : MgF{sub 2} laser emitting 200-{mu}s pulses at a wavelength 1.91 {mu}m. In the case of Doppler broadening of absorption lines at room temperature, the sensitivity of detection of O{sub 2} (a{sup 1} {Delta}{sub g}) is {approx} (2 - 5) x 10{sup 14} cm{sup -3} . It is shown that the gas temperature can be calculated from the dependence of absorption cross sections for individual lines on the rotational quantum number. (laser applications and other topics in quantum electronics)