Leonid L Losev

Laser-pumped molecular laser

The parameters of laser-pumped molecular lasers are investigated. It is established that the energy and tuning characteristics of an NH3 laser (Eg = 1.5 J, efficiency 20%, Pav = 20 W, radiation frequency tuning band 753–890 cm-1) are decisively influenced by the addition of N2. A focusing raster optical-pumping system has made it possible to obtain a specific lasing energy 12 J/liter. A CF4 laser with lasing energy 40 mJ operates in the 612–655 cm-1 band. Experiments on dissociation of the molecules CCl4 and UF6 were carried out with the aid of NH3 and CF4 lasers. The systems and methods of producing Raman lasers (RL) are presented. An effective RL amplifier on rotational transitions in compressed H2, which transforms tens of beams of Nd lasers into one coherent beam of the first Stokes component with λ ≅ 1.13 μm at an efficiencyup to 70%, is described.

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.

Temporal compression of pulses from a 100-KHz-repetiton-rate femtosecond ytterbium laser

We report the temporal compression a femtosecond ytterbium laser pulse at a pulse repetition rate of 100 kHz using the effect of nonlinear self-phase modulation in a gas-filled capillary. A 260-fs laser pulse is compressed down to 17 fs with an energy efficiency of 40%. An average radiation power at the compressor output is 2 W. At a second compression stage, the time contrast is increased and the pulse duration is reduced in the process of the second harmonic generation in a KDP crystal. The obtained pulses have a duration of 11 fs at an efficiency of 35%.

1-kHz-repetition-rate femtosecond Raman laser

A femtosecond Raman laser utilising compressed hydrogen is experimentally investigated under pumping by radiation from a 1-kHz-repetition-rate Ti : sapphire laser. In the regime of double-pulse pumping, the conditions are determined, which correspond to the minimal energy dispersion of Stokes pulses. The optical scheme is realised, which is capable of ensuring the long-term stability of the average power of the first Stokes component with a variation of less than 2%. The Stokes pulses are produced with a pulse duration of 60 fs and energy of 0.26 mJ at a conversion efficiency of 14%.

Note: 15-fs, 15-μJ green pulses from two-stage temporal compressor of ytterbium laser pulses.

15-fs, 15-μJ light pulses at the central wavelength of 515 nm were generated by two-stage nonlinear compression of 300-fs, 150-μJ ytterbium laser pulses. The compression was based on the pulse spectrum broadening by self-phase modulation in gas filled capillary and second harmonic generation in crystal.