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Valentin Petrov

Bio: Valentin Petrov is an academic researcher from Jiangsu Normal University. The author has contributed to research in topics: Laser & Slope efficiency. The author has an hindex of 54, co-authored 743 publications receiving 12127 citations. Previous affiliations of Valentin Petrov include Max Planck Society & Conservatoire national des arts et métiers.


Papers
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Journal ArticleDOI
TL;DR: In this article, the development of parametric devices down-converting the laser frequency to the mid-infrared (3-30 µm) based on non-oxide nonlinear optical crystals is reviewed.

335 citations

Journal ArticleDOI
TL;DR: In this article, the growth methodology for bulk and epitaxial layers, its structural, thermo-mechanical, and optical properties, the Yb 3+ and Tm 3+ spectroscopy, and present laser results obtained in several operational regimes both with Ti:sapphire and direct diode laser pumping using IngaAs and AlGaAs diodes near 980 and 800 nm, respectively.
Abstract: High-quality crystals of monoclinic KLu(WO 4 ) 2 , shortly KluW, were grown with sizes sufficient for its characterization and substantial progress was achieved in the field of spectroscopy and laser operation with Yb 3- and Tm 3+ -doping. We review the growth methodology for bulk KluW and epitaxial layers, its structural, thermo-mechanical, and optical properties, the Yb 3+ and Tm 3+ spectroscopy, and present laser results obtained in several operational regimes both with Ti:sapphire and direct diode laser pumping using IngaAs and AlGaAs diodes near 980 and 800 nm, respectively. The slope efficiencies with respect to the absorbed pump power achieved with continuous-wave (CW) bulk and epitaxial Yb:KLuW lasers under Ti:sapphire laser pumping were ≈ 57 and ≈ 66%, respectively. Output power as high as 3.28 W were obtained with diode pumping in a simple two-mirror cavity where the slope efficiency with respect to the incidert pump power reached ≈ 78%. Passively Q-switched laser operation of bulk Yb:KluW was realized with a Cr:YAG saturable absorber resulting in oscillation at ≈ 1031 nm with a repetition rate of 28 kHz and simultaneous Raman conversion to ≈ 1138 nm with maximum energies of 32.4 and 14.4 μJ, respectively. The corresponding pulse durations were 1.41 and 0.71 ns. Passive mode-locking by a semiconductor saturable absorber mirror (SESAM) produced bandwidth-limited pulses with duration of 81 fs (1046 nm, 95 MHz) and 114 fs (1030 nm, 101 MHz) for bulk and epitaxial Yb:KLuW lasers, respectively. Slope efficiency as high as 69% with respect to the absorbed power and an output power of 4 W at 1950 nm were achieved with a diode-pumped Tm:KLuW laser. The slope efficiency reached with an epitaxial Tm:KluW laser under Ti:sapphire laser pumping was 64 %. The tunability achieved with bulk and epitaxial Tm:KLuW lasers extended from 1800 to 1987 nm and from 1894 to 2039 nm, respectively.

230 citations

Journal ArticleDOI
TL;DR: In this paper, single crystals LiGaX 2 (X = S, Se, Te) of optical quality were grown, with transparency ranges at 5 cm -1 absorption level of 0.32-11.6 μm, 0.37-13.2 μm and 0.54-14.2 µm, respectively.
Abstract: Single crystals LiGaX 2 (X = S, Se, Te) of optical quality were grown, with transparency ranges at 5 cm -1 absorption level of 0.32-11.6 μm, 0.37-13.2 μm and 0.54-14.2 μm, respectively. The first two, LiGaS 2 and LiGaSe 2 , have a wurtzite-type structure whereas LiGaTe 2 is tetragonal (chalcopyrite lattice). The three refractive indices were measured in the whole transparency ranges of LiGaS 2 and LiGaSe 2 and n a and n c were found to be very close (quasi-uniaxial optical anisotropy) with a crosspoint at 6.5 μm (LiGaS 2 ) and 8 μm (LiGaSe 2 ). Sellmeier equations were fitted and phase-matching conditions for second harmonic generation (SHG) were calculated: the 1.467-11.72 μm spectral range for the fundamental is covered by LiGaS 2 and LiGaSe 2 .

202 citations

Journal ArticleDOI
TL;DR: In this paper, the optical properties of the monoclinic crystal of the ytterbium transition have been characterized and the optical anisotropy of the material has been characterized.
Abstract: We present our recent achievements in the growing and optical characterization of $\mathrm{KYb}({\mathrm{WO}}_{4}{)}_{2}$ (hereafter KYbW) crystals and demonstrate laser operation in this stoichiometric material. Single crystals of KYbW with optimal crystalline quality have been grown by the top-seeded-solution growth slow-cooling method. The optical anisotropy of this monoclinic crystal has been characterized, locating the tensor of the optical indicatrix and measuring the dispersion of the principal values of the refractive indices as well as the thermo-optic coefficients. Sellmeier equations have been constructed valid in the visible and near-IR spectral range. Raman scattering has been used to determine the phonon energies of KYbW and a simple physical model is applied for classification of the lattice vibration modes. Spectroscopic studies (absorption and emission measurements at room and low temperature) have been carried out in the spectral region near $1 \ensuremath{\mu}\mathrm{m}$ characteristic for the ytterbium transition. Energy positions of the Stark sublevels of the ground and the excited state manifolds have been determined and the vibronic substructure has been identified. The intrinsic lifetime of the upper laser level has been measured taking care to suppress the effect of reabsorption and the intrinsic quantum efficiency has been estimated. Lasing has been demonstrated near 1074 nm with $41%$ slope efficiency at room temperature using a 0.5 mm thin plate of KYbW. This laser material holds great promise for diode pumped high-power lasers, thin disk and waveguide designs as well as for ultrashort (ps/fs) pulse laser systems.

200 citations

Journal ArticleDOI
TL;DR: Mode locking of an Yb-doped bulk laser in the 1 microm spectral range using a single-walled carbon nanotube saturable absorber (SWCNT-SA) is demonstrated for the first time, to the authors' knowledge.
Abstract: Mode locking of an Yb-doped bulk laser in the 1 μm spectral range using a single-walled carbon nanotube saturable absorber (SWCNT-SA) is demonstrated for the first time, to our knowledge. Passive mode locking of an Yb:KLuW laser resulted in nearly transform-limited pulses as short as 115 fs at 1048 nm. In addition, the nonlinear response of the SWCNT-SA was measured, yielding a modulation depth of 0.25% and a relaxation time of 750 fs.

170 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this paper, the main aspects of ultrashort laser pulse filamentation in various transparent media such as air (gases), transparent solids and liquids are introduced and discussed.

2,282 citations

Journal Article
TL;DR: In this article, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter, which was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.
Abstract: Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

1,285 citations

Journal ArticleDOI
A. Braun1, Georg Korn1, X. Liu1, D. Du1, Jeff Squier1, Gerard Mourou1 
TL;DR: The self-channeling of ultrashort laser pulses through 20 m of air was demonstrated and a preliminary model is shown to explain these results.
Abstract: The self-channeling of ultrashort laser pulses through 20 m of air was demonstrated. The channeled pulse was measured to have 0.75 mJ of energy, a diameter of 80 microm FWHM, and a modulated spectrum. All these values were measured to be fairly constant during the propagation of the pulse. A preliminary model is shown to explain these results.

1,205 citations

Journal ArticleDOI
TL;DR: A detailed overview of the physics and applications of optical dark solitons can be found in this article, where the authors discuss the instability-induced dynamics of dark-solitons in the models of generalized (i.e., non-Kerr) optical nonlinearities.

1,076 citations