Diffraction-limited atomic iodine photodissociation laser

A high-reliability diffraction-limited atomic iodine photodissociation laser is described. It is shown that a diffraction-limited output beam is obtained when the laser pulse is extracted before the onset of gain-medium inhomogeneities caused by non-uniform deposition of the pump radiation. No degradation of the beam focusability is observed for intensities at which the final amplifier is heavily saturated.This work supported by the United States Department of Energy.     

Subnanosecond high-pressure iodine photodissociation laser oscillator

A simultaneously Q-switched and acousto-optic mode-locked high-pressure iodine photodissociation (=1.315m) oscillator system, capable of generating pulse-widths as short as 160 ps is described. Good agreement is found between theory and experiment for the pressure-dependence of the modelocked pulse-width. The results indicate that pulse-widths approaching 100ps should be obtainable with this type of system.     

Kinetics of the photodissociation iodine laser with slow pumping

Systematic calculations of maximum inversion were performed for iodine photodissociation laser in dependence on the mixture composition. The flash-lamp radiation was modelled as emanating from an optically thin Xe plasma. Duration of the pumping pulse is about 300 s. The sensitivity of the model to the values of kinetic constants was also tested.     

Conversion to the third harmonic of the iodine photodissociation laser PERUN

The frequency tripling of the iodine laser PERUN is described. The maximum conversion efficiency to the third harmonic is 50%, which represents about 20 J of the 3 laser beam.     

100 GW pulsed iodine photodissociation laser system PERUN I

The photodissociation iodine laser system PERUN I is described. The laser generates and amplifies the subnanosecond pulse with the energy about 80 J of the fundamental wavelength 1·315 μm and beam diameter 10 cm. The physical principles of this type of the high power laser are briefly explained and the laser system and its characteristics are described from the physical and technical point of view. Special attention is paid to the realization of such system with the slow optical pumping (≈300 μs).     

Conversion to the second harmonic of high power iodine photodissociation laser system PERUN

The frequency doubling of the iodine laser PERUN is described. The maximum conversion efficiency of 55% is attained, the energy of the red (=0.657m) radiation is 20 J.     

Broadband femtosecond OPCPA system driven by the single-shot narrow-band iodine photodissociation laser SOFIA

A two-stage optical parametric amplifier driven by a frequency-tripled beam from the high-energy iodine laser system SOFIA was built. This single-shot Optical Parametric Chirped Pulse-Amplification facility (OPCPA) and the system synchronizing the pump and signal pulses are described in detail. The chirped seed pulse of a Ti:sapphire oscillator running at the central wavelength of 800?nm is amplified in the two-stage (LBO and KDP) optical parametric amplifier over 10⁸ times. The amplified spectral bandwidth of 68?nm corresponds to the pulse duration of 14?fs when a transform-limited pulse is assumed. This implies a compressed pulse of TW power. Systematic gain measurements reveal a good match with the theoretical predictions. Signal and idler beam fluence profiles are presented. The suitability of the iodine photo-dissociation laser as a pump source for the OPCPA technique is thus proved for the first time experimentally. A distinctive feature of the iodine laser is its very narrow gain bandwidth (<0.1?cm^?1) and, therefore, the conventional chirped-pulse amplification technique does not lead to pulse durations at the femtosecond level.     

Quenching kinetics and small signal gain spectrum of the ZnI photodissociation laser

By photodissociation ZnI₂ with 193 nm (ArF) laser radiation, the rate constants for quenching of the upper and lower energy levels of the ZnI (B → X) laser by ZnI₂ have been measured to be (1.7 ± 0.2) × 10^-9 and (1.4 ± 0.4) × 10^-9 cm³ s^-1, respectively. Although the former rate constant was found to be laser intensity-dependent for I ? 10⁵ W cm^-2, the ZnI(B) state radiative lifetime was determined to be 26 ± 4 ns. Also, the small signal gain coefficient, g₀, of this molecular laser has a peak value of ? 15% cm^-1 at λ ? 602 nm and exceeds 5% cm^-1 for 591 nm ≤ λ ≤ 608 nm for a potential tuning range of at least 170 Å.     

Femtosecond control of photoionization and photodissociation of sodium iodine molecules by laser pulse

Wave packet propagation techniques are used to find experimentally reliable laser parameters that yield optimal production.The photoionization and photodissociation dynamics of sodium iodine molecules are interpreted into several channels.Several frequencies are found to be suitable for NaI molecules during the photoionization and dissociation processes.Photon-dressed excited states and electron-dressed ionic continuum states facilitate the search for available laser parameters.     

Kinetics of iodine photodissociation laser in a free running regime at slow pumping

Systematic analysis of pumping kinetics of iodine photodissociation laser was performed in a free running regime. For a practical example, the A 3 amplifier of the iodine laser system PERUN was placed inside a planar resonator and the output energy was calculated in dependence on the mixture composition and compared with the extractable energy in the amplifier case.     

A photodissociation high-power iodine laser with improved capacity to break down solid targets

A single-pulse high-power photodissociation iodine laser (PIL) was developed. It is pumped by the radiation of an open electric discharge (31.3 kJ, 20 kA). The total output energy at a wavelength of 1316 nm was found to be (30±5) J for ∼100-μs-wide pulses. To improve the breakdown capacity, each pulse was modulated with a train of five to six narrower pulses by applying a variable magnetic field from the discharge pinch to the laser medium.     

Possibility of separating the isotopes127I and129I with the aid of a photodissociation iodine laser

A method for separating iodine isotopes is proposed, based on the large difference between the rate constants of the excited I*(²P_1/2) and unaxclted iodine atoms with radicals CF₃ and with Cl₂ molecules, and on the possibility of selectively acting on the₁₂₇I atoms in the states²P_1/2 and²P_3/2 by radiation from a photodissociation R¹²⁷I iodine laser (λ = 1.315 μm). The possibility of separating the pure isotope¹²⁹I and the mixture¹²⁷I with¹²⁹I is investigated.     

Image restoration in a highly non-steady-state regime of stimulated Brillouin scattering in a photodissociation iodine laser

For what we believe to be the first time, mask restoration in a backscattered signal in a highly non-steady-state regime of stimulated Brillouin scattering was attained. A special two-lens system of laser beam insertion into a scattering medium was used. Results are compared with those of ordinary one-lens focusing.     

Focal spot analysis of optical inhomogeneities appearing in the working medium of an iodine photodissociation laser with flashlamp pumping

We report on the results of experimental studies of optical inhomogeneities appearing in the working medium of an iodine photodissociation laser operating in the inversion accumulation mode and in the free-running mode. The dynamics of evolution of optical inhomogeneities in the free-running mode is studied experimentally.     

Atomic mercury photodissociation laser in the visible

Stimulated emission on two new pulsed laser lines in atomic mercury is reported. The laser emits at 435.8 and 546.1 nm, corresponding to the transitions 7 ³S₁ → 6 ³P₁ and 7 ³S₁ → 6 ³P₀ of the neutral atomic mercury atom. Population inversion is generated by photodissociation of HgI₂ vapor with a KrF laser at 248 nm. 150mJ of KrF laser radiation were focused into the HgI₂ cell by means of a cylindrical lens in a transverse pumping configuration. With a single end mirror pulses with a peak power of 3 kW and duration of approximately 1 ns were generated. The pumping mechanism is proposed to be a sequential three-photon process.     

Miniaturization of a thalliumiodide photodissociation laser

We report on the operation of a thallium photodissociation laser with an active medium in the form of a thin layer on a quartz wall. Laser emission has been obtained with layer thicknesses below 100 m. This gas laser seems to be feasible with an active volume as small as 10^–1 to 10^–2 mm³.     

Iodine photodissociation laser system Perun II

A construction and exploitation of a medium size iodine photodissociation laser system Perun II is reported. This laser produced pulses of infrared light (=1.315m) up to 50 J in energy and 300 ps in duration. The diameter of the beam is 82 mm. The beam divergence is about 4×10^–4 rad. The laser beam can be focused in a focal spot of a power density exceeding 10¹⁴ W/cm². The resuls of measurements of basic plasma parameters on an Al foil target are also presented. A recent improvement of the system includes a conversion to the second harmonic by a DKDP crystal.Presented at bilateral international seminar of High Temperature Laser Plasma and High Gain Iodine Lasers held on 4 July 1991 in the Inst. of Physics, Czechosl. Acad. Sci., in Prague (organized by Division of Optics of the Inst. of Physics, Czechosl. Acad. Sci., and Physical Section (Plasma Division) of the Union of Czech Mathematicians and Physicists.     

Power optimization of a Tl photodissociation laser

Conditions for the operation of a Tl photodissociation laser, in view of power optimization, have been determined. A crucial parameter is found to be quenching of the upper laser level. A value for the quenching cross-section of the 7² S _1/2 Tl state by the TlI molecules of 2×10^–14 cm² has been measured.