V. I. Trunov

Coherent combining of femtosecond pulses parametrically amplified in BBO crystals.

We report on the first experimental realization of coherent combining of parametrically amplified femtosecond pulses. The proposed and implemented two-loop active stabilization system allows us to achieve 110 as relative timing jitter between combined pulses, which is necessary for efficient coherent beam combining. In each channel of the two-channel laser setup, pulses were parametrically amplified in β-BaB2O4 (BBO) crystals to 50 μJ energy, compressed to 49 fs duration, and then coherently combined with efficiency as high as 97%. Currently, it is the shortest duration of amplified pulses for which coherent combining is demonstrated.

Highly nonlinear fundamental mechanisms of excitation and coloring of wide-gap crystals by intense femtosecond laser pulses

Analysis of the spatial distribution of the color centers formed in wide-gap LiF and MgF2 crystals in a laser beam channel has shown that these centers are formed in numerous longitudinal filaments into which a laser beam splits when propagating in a medium. The luminescence of the produced color centers is photoluminescence, which is excited by the supercontinuum radiation in the filaments.

High-intensity femtosecond laser systems based on coherent combining of optical fields

The basic design principles of high-intensity laser systems based on coherent combining of radiation of multichannel laser facilities are considered. The influence of the instability of parameters of individual beams on coherent combining efficiency is analyzed, and requirements on their values for realization of high-efficiency coherent combining are determined. The fundamental possibility of coherent combining of parametrically amplified femtosecond pulses is experimentally demonstrated for the first time. Combining pulses with an energy of ∼1 mJ (pulse duration of 25–30 fs) with an efficiency exceeding 83% is realized by using a spherical mirror and a specially developed high-precision electro-optical relative time jitter stabilization scheme, which ensures its stability at ∼170 as level. The analysis conducted and the experimental data confirm that there are no fundamental limitations on intensity scaling of the high-intensity laser system based on coherent combining being developed at the Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences.

Design of high gain OPCPA for multiterawatt and petawatt class systems on large aperture LBO crystals

Comparative analysis of optimal scheme of non-collinear optical chirped-pulse parametric amplification of fewcycle femtosecond pulses from Ti:Sa laser in LBO and DKDP crystals pumped by picosecond pulses up to petawatt level is presented. A flexible code, based on the extended model of parametric amplification, which takes into account the large set of effects such as saturation, phase self-modulation, influence of beam divergence, thermal effects, and amplification of spontaneous emission was realized. A way of creating nearly 1 PW system based on LBO crystals with transform-limited pulse duration about 9 fs has been demonstrated. Comparison between DKDP and LBO crystal showed that the latter is much better for OPCPA petawatt system design than DKDP.

Spectroscopic and laser properties of BeLaAl11O19 single crystals doped with Cr3+, Ti3+, and Nd3+ ions

The new laser crystals BeLaAl11O19 doped with Cr3+, Ti3+ and Nd3+ ions were grown by the Czochralski technique. The absorption and fluorescence spectra of impurity ions are reported and the temperature dependence of the fluorescence lifetime are described. The laser properties of these ions were investigated. The laser action has been achieved on 4F3/2-4I11/2 (1052 nm) transition of Nd3+ -ions under selective laser pumping. The physical properties of BeLaAl11O19 crystal were studied: the values of all independent component of elastic constant tensor were determined. On the base of a number of dynamic parameters of crystals, such as Youngs modulus, the shear modulus, the volume elasticity modulus and Poissons factor, Debye temperature and specific heat capacity were calculated. The investigation show that the BeLaAl11O19 is a promising host for a creature the new solid state laser media.

Laser-driven plasma wakefield electron acceleration and coherent femtosecond pulse generation in X-ray and gamma ranges

The laser wakefield acceleration (LWFA) of electrons in capillaries and gas jets followed by inverse Compton scattering of high intensity femtosecond laser pulses is discussed. The drive and scattered pulses will be produced by the two-channel multi-terawatt laser system developed in ILP SB RAS.

Ultrarelativistic laser systems based on coherent beam combining

Conceptual design for femtosecond laser system of exawatt class, based on multi-channel amplifier and coherent field combining of petawatt amplifier channels with phase-frequency controlled radiation by optical clock are discussed. The scheme of start petawatt level few-cycle laser system with stable phase-frequency parameters determinated by the accuracy of the optical standard based on parametric amplification in big-size LBO crystals pumped by picosecond pulses is analyzed.

Aberration-free broadband stretcher-compressor system for femtosecond petawatt-level laser system based on parametric amplification

An optimal stretcher-compressor scheme is designed for laser facilities based onbased on optical parametric chirped-pulse amplification under picosecond (∼100 ps) pumping, which enables one to attain petawatt peak power of pulses less than 10 fs with high contrast and low aberrations. The stretcher design is based on an Öfner telescope with spherical mirrors and two diffraction gratings, one being placed at the center of the spherical mirrors. It is shown to be the only possible aberration-free stretcher design. The simulation performed has shown that a compressor consisting of four transmission diffraction gratings with an aperture 112 × 125 mm, a thickness of 3 mm, and chirped mirrors with 100-mm aperture that introduce −4500 fs2 dispersion allows amplified pulse compression down to <10 fs length and 1 PW peak power with the total B-integral lower than 1. The designed stretcher-compressor system is planned to be implemented in the high power femtosecond laser system being developed at ILP SB RAS.

Femtosecond SESAM lasers with shortlength cavity

Femtosecond pulse generation in Al2O3:Ti3+ laser with some types of laser cavity configuration with semiconductor saturable absorber mirror (SESAM), based on semiconductor quantum well low temperature (LT) GaAs/AlAs, GaxIn1-xAs/AlyGa1-yAs saturated absorbers and metal mirrors have been investigated.

Implementation of multiterawatt femtosecond laser system at kilohertz repetition rate

The report presents the basic principles of creation, scheme and the components of multiterawatt laser system at kilohertz repetition rate based on parametric amplification of femtosecond pulses and laser amplification of picosecond pulses for pumping of stages of parametric amplifier. On developed element base in pump channel of laser system, parameters of regenerative amplifier with output energies about 1 mJ at repetition rate of 1 kHz and central wavelength 1030 nm are experimentally investigated. Optical scheme of multipass cryogenic amplifier based on diode pumped Yb:Y2O3 laser ceramics is developed and parameters for increasing of output energy up to ~ 0.25-0.35 J are determined.