Experiments of our earlier work on the study of stimulated thermal scattering of the second harmonic of neodymium laser radiation in toluene are reproduced in order to confirm the put forward hypothesis about the nature of the laser beam structure decay in the focal plane of a short-focus lens. Experiments were carried out under similar conditions, but with a liquid (CCl4), in which there is no two-photon absorption of the second harmonic radiation from a neodymium laser. A conclusion is made that the spatial structure decay of the laser beam of the second harmonic of the Nd : YAG laser radiation focused by short-focus lenses with a numerical aperture NA ∼ 0.1 in toluene is associated with two-photon absorption.
{"title":"Formation of the spatial structure of pump radiation in the focal plane of a lens for different types of stimulated light scattering","authors":"A. Gordeev, V. F. Efimkov, I. Zubarev","doi":"10.1070/qel18013","DOIUrl":"https://doi.org/10.1070/qel18013","url":null,"abstract":"Experiments of our earlier work on the study of stimulated thermal scattering of the second harmonic of neodymium laser radiation in toluene are reproduced in order to confirm the put forward hypothesis about the nature of the laser beam structure decay in the focal plane of a short-focus lens. Experiments were carried out under similar conditions, but with a liquid (CCl4), in which there is no two-photon absorption of the second harmonic radiation from a neodymium laser. A conclusion is made that the spatial structure decay of the laser beam of the second harmonic of the Nd : YAG laser radiation focused by short-focus lenses with a numerical aperture NA ∼ 0.1 in toluene is associated with two-photon absorption.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"65 1","pages":"328 - 331"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82709791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Shlenov, V. Kompanets, A. A. Dergachev, V. Kandidov, S. Chekalin, F.I. Soifer
The results of experimental and theoretical study of the self-action of femtosecond optical vortices in the region of anomalous group velocity dispersion in fused silica and fluorides are presented. Multiple filamentation of an axially asymmetric annular beam with a phase dislocation of topological charge m = 1 at a wavelength of 1800 nm in a LiF crystal is investigated. It is found that for the experimentally recorded intensity profile of a vortex beam with two maxima on the diameter, the critical self-focusing power is approximately two times larger than the critical power of a unimodal Gaussian beam. In pulses with supercritical power in the vicinity of the intensity maxima, two coupled filaments, separated by a phase dislocation, are formed on the annular profile of the optical vortex, which prevents energy exchange during their formation. The length of vortex-beam plasma channels in a single pulse is found to be about 300 μm at a diameter of about 2 μm, which is close to the characteristics of plasma channels in a Gaussian beam.
{"title":"Femtosecond multiple filamentation of an optical vortex in the mid-IR wavelength range in fused silica and fluorides","authors":"S. Shlenov, V. Kompanets, A. A. Dergachev, V. Kandidov, S. Chekalin, F.I. Soifer","doi":"10.1070/qel18028","DOIUrl":"https://doi.org/10.1070/qel18028","url":null,"abstract":"The results of experimental and theoretical study of the self-action of femtosecond optical vortices in the region of anomalous group velocity dispersion in fused silica and fluorides are presented. Multiple filamentation of an axially asymmetric annular beam with a phase dislocation of topological charge m = 1 at a wavelength of 1800 nm in a LiF crystal is investigated. It is found that for the experimentally recorded intensity profile of a vortex beam with two maxima on the diameter, the critical self-focusing power is approximately two times larger than the critical power of a unimodal Gaussian beam. In pulses with supercritical power in the vicinity of the intensity maxima, two coupled filaments, separated by a phase dislocation, are formed on the annular profile of the optical vortex, which prevents energy exchange during their formation. The length of vortex-beam plasma channels in a single pulse is found to be about 300 μm at a diameter of about 2 μm, which is close to the characteristics of plasma channels in a Gaussian beam.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"145 1","pages":"322 - 327"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88633018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Slipchenko, V. Golovin, O. Soboleva, I. Lamkin, N. Pikhtin
This paper presents a 2D model of a high-power semiconductor laser, which takes into account carrier transport across the layers of its heterostructure and longitudinal spatial hole burning (LSHB), an effect related to the nonuniform gain distribution along the cavity axis. We show that the use of the 2D model which takes into account carrier transport across the layers of the heterostructure allows an appreciable contribution of LSHB to saturation of light – current characteristics to be demonstrated. The LSHB effect, causing a decrease in the output optical power of semiconductor lasers, is shown to be stronger at high drive currents and low output mirror reflectivities. In the case of high drive currents, the LSHB-induced drop in power is related to the faster growth of internal optical and recombination losses because of the nonuniform current density distribution along the cavity axis, such that the highest current density can be almost twice the lowest one. LSHB is shown to increase the power stored in a Fabry – Perot cavity, which is an additional mechanism reducing the output optical power.
{"title":"Analysis of light – current characteristics of high-power semiconductor lasers (1060 nm) in a steady-state 2D model","authors":"S. Slipchenko, V. Golovin, O. Soboleva, I. Lamkin, N. Pikhtin","doi":"10.1070/qel18015","DOIUrl":"https://doi.org/10.1070/qel18015","url":null,"abstract":"This paper presents a 2D model of a high-power semiconductor laser, which takes into account carrier transport across the layers of its heterostructure and longitudinal spatial hole burning (LSHB), an effect related to the nonuniform gain distribution along the cavity axis. We show that the use of the 2D model which takes into account carrier transport across the layers of the heterostructure allows an appreciable contribution of LSHB to saturation of light – current characteristics to be demonstrated. The LSHB effect, causing a decrease in the output optical power of semiconductor lasers, is shown to be stronger at high drive currents and low output mirror reflectivities. In the case of high drive currents, the LSHB-induced drop in power is related to the faster growth of internal optical and recombination losses because of the nonuniform current density distribution along the cavity axis, such that the highest current density can be almost twice the lowest one. LSHB is shown to increase the power stored in a Fabry – Perot cavity, which is an additional mechanism reducing the output optical power.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"112 1","pages":"343 - 350"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89525024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Butaev, Y. Skasyrsky, V. Kozlovsky, A. Andreev, I. Yarotskaya, A. Marmalyuk
A pulsed semiconductor disk laser based on the Al x Ga1 – x As/Al y Ga1 – y As structure with resonantly periodic gain and a built-in Bragg mirror emitting at a wavelength near 780 nm is studied. The laser characteristics are presented both for pumping by an electron beam and for optical pumping by laser diode radiation with a wavelength of 450 nm. Under pumping by an electron beam, a peak power of 4.4 W is achieved with a slope efficiency of over 10 %, while under optical pumping, the power is 0.2 W with a slope efficiency of 2.2 % and approximately the same cavity parameters. Possible reasons for the lower powers and efficiency under optical pumping are discussed.
研究了一种具有共振周期增益的Al x Ga1 - x As/Al y Ga1 - y As结构的脉冲半导体圆盘激光器，该激光器内置布拉格反射镜，发射波长接近780 nm。给出了电子束抽运和波长为450 nm的激光二极管辐射光抽运的激光特性。电子束抽运的峰值功率为4.4 W，斜率效率超过10%;光抽运的峰值功率为0.2 W，斜率效率为2.2%，腔体参数基本相同。讨论了光泵浦下功率和效率较低的可能原因。
{"title":"Semiconductor disk laser with a wavelength of 780 nm based on a MOCVD-grown Al x Ga1–x As/Al y Ga1–y As heterostructure with optical and electron beam pumping","authors":"M. Butaev, Y. Skasyrsky, V. Kozlovsky, A. Andreev, I. Yarotskaya, A. Marmalyuk","doi":"10.1070/qel18017","DOIUrl":"https://doi.org/10.1070/qel18017","url":null,"abstract":"A pulsed semiconductor disk laser based on the Al x Ga1 – x As/Al y Ga1 – y As structure with resonantly periodic gain and a built-in Bragg mirror emitting at a wavelength near 780 nm is studied. The laser characteristics are presented both for pumping by an electron beam and for optical pumping by laser diode radiation with a wavelength of 450 nm. Under pumping by an electron beam, a peak power of 4.4 W is achieved with a slope efficiency of over 10 %, while under optical pumping, the power is 0.2 W with a slope efficiency of 2.2 % and approximately the same cavity parameters. Possible reasons for the lower powers and efficiency under optical pumping are discussed.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"6 1","pages":"362 - 366"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79127866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is experimentally shown that during laser annealing of micron layers of fluorocarbon oil by high-power KrF laser radiation pulses, C : F nanocoatings with a thickness of up to ∼100 nm can be synthesised on a leucosapphire surface. The absorption spectra of these coatings, measured in the 0.19 – 6 μm range, virtually coincided with the absorption spectra of fluorographene in the quantum energy range of 5 ± 1 eV. The nanohardness and elasticity modulus of the C : F nanocoatings are found to be 7 and 250 GPa, respectively, which is close to the characteristics of fluorographene.
{"title":"Absorption spectra and mechanical properties of C : F nanocoatings deposited from laser plasma onto leucosapphire surface","authors":"P. B. Sergeev, K. Kravchuk, N. V. Morozov","doi":"10.1070/qel18027","DOIUrl":"https://doi.org/10.1070/qel18027","url":null,"abstract":"It is experimentally shown that during laser annealing of micron layers of fluorocarbon oil by high-power KrF laser radiation pulses, C : F nanocoatings with a thickness of up to ∼100 nm can be synthesised on a leucosapphire surface. The absorption spectra of these coatings, measured in the 0.19 – 6 μm range, virtually coincided with the absorption spectra of fluorographene in the quantum energy range of 5 ± 1 eV. The nanohardness and elasticity modulus of the C : F nanocoatings are found to be 7 and 250 GPa, respectively, which is close to the characteristics of fluorographene.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"25 1","pages":"376 - 381"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80047210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Visible radiation spectra of polycrystalline graphite under electrical and laser excitation is studied. It is shown that two different mechanisms of photon emission with a broadband spectrum are implemented in this material. The radiation arising as a result of resistive heating is thermal radiation, whose parameters are close to those of blackbody radiation. The laser-induced secondary radiation in the visible range is anti-Stokes luminescence. A red shift of the laser-induced radiation from fine-grained graphite with respect to the similar spectrum of a bulk sample is observed.
{"title":"Broadband emission from polycrystalline graphite","authors":"S. Rekhviashvili, D. Gaev, Z. Margushev","doi":"10.1070/qel18018","DOIUrl":"https://doi.org/10.1070/qel18018","url":null,"abstract":"Visible radiation spectra of polycrystalline graphite under electrical and laser excitation is studied. It is shown that two different mechanisms of photon emission with a broadband spectrum are implemented in this material. The radiation arising as a result of resistive heating is thermal radiation, whose parameters are close to those of blackbody radiation. The laser-induced secondary radiation in the visible range is anti-Stokes luminescence. A red shift of the laser-induced radiation from fine-grained graphite with respect to the similar spectrum of a bulk sample is observed.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"21 1","pages":"382 - 385"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74040803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new method for two-stage laser enrichment of carbon-13 (13C) by isotope-selective IR multiphoton dissociation of Freon molecules is considered, which makes it possible to achieve a concentration of 13C up to 99 % or higher with high productivity. At the first stage, as a result of the selective dissociation of CF2HCl (Freon-22) molecules, it is expected to obtain a C2F4 dissociation product enriched in 13C up to 30 % – 50 %. At the second stage, CF2Br2 (Freon-12B2) is proposed to be used as a working substance, which is synthesised from enriched C2F4, and the enrichment process is carried out by selective deep ‘burning-out’ of the 12C-containing component. Experiments on multiphoton dissociation of Freon-12B2 with an initial 13CF2Br2 concentration of 30 % in a mixture with oxygen by pulsed CO2 laser radiation are performed. It is shown that reaching a 13CF2Br2 concentration of no lower than 99 % is possible at high values of the elementary separation act parameters: 15 % – 18 % dissociation yield and 40 – 75 selectivity for 12CF2Br2 molecules.
{"title":"Efficient two-stage laser enrichment up to 99% of carbon-13 isotope by IR multiphoton dissociation of Freon molecules","authors":"V. Laptev, S. V. Pigul’skiĭ","doi":"10.1070/qel18025","DOIUrl":"https://doi.org/10.1070/qel18025","url":null,"abstract":"A new method for two-stage laser enrichment of carbon-13 (13C) by isotope-selective IR multiphoton dissociation of Freon molecules is considered, which makes it possible to achieve a concentration of 13C up to 99 % or higher with high productivity. At the first stage, as a result of the selective dissociation of CF2HCl (Freon-22) molecules, it is expected to obtain a C2F4 dissociation product enriched in 13C up to 30 % – 50 %. At the second stage, CF2Br2 (Freon-12B2) is proposed to be used as a working substance, which is synthesised from enriched C2F4, and the enrichment process is carried out by selective deep ‘burning-out’ of the 12C-containing component. Experiments on multiphoton dissociation of Freon-12B2 with an initial 13CF2Br2 concentration of 30 % in a mixture with oxygen by pulsed CO2 laser radiation are performed. It is shown that reaching a 13CF2Br2 concentration of no lower than 99 % is possible at high values of the elementary separation act parameters: 15 % – 18 % dissociation yield and 40 – 75 selectivity for 12CF2Br2 molecules.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"45 1","pages":"371 - 375"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87004858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optical frequency combs have revolutionised accurate frequency and time measurements and have enabled broadband and simultaneously high resolution spectroscopic measurements that were not previously possible. This paper is an overview of the main results of the previously performed work, describing a new approach to extending frequency combs to the mid-infrared ‘molecular signature’ range using a subharmonic generator based on an optical parametric oscillator operating in degenerate mode. Such an instrument acts as an efficient frequency divider that rigorously down-converts and augments the spectrum of a pump laser frequency comb while maintaining its coherence. Our recent result is the demonstration of a subharmonic system with a two-octave spectrum, 3 – 12 μm, which covers vibrational resonances for most molecular species. Potentially, through frequency division in the coherent subharmonic optical parametric amplifier regime, this method can be used to obtain intense long-wavelength pulses for high-field physics applications.
{"title":"Ultra-broadband mid-infrared frequency combs produced by optical subharmonic generation","authors":"K. Vodopyanov","doi":"10.1070/qel18012","DOIUrl":"https://doi.org/10.1070/qel18012","url":null,"abstract":"Optical frequency combs have revolutionised accurate frequency and time measurements and have enabled broadband and simultaneously high resolution spectroscopic measurements that were not previously possible. This paper is an overview of the main results of the previously performed work, describing a new approach to extending frequency combs to the mid-infrared ‘molecular signature’ range using a subharmonic generator based on an optical parametric oscillator operating in degenerate mode. Such an instrument acts as an efficient frequency divider that rigorously down-converts and augments the spectrum of a pump laser frequency comb while maintaining its coherence. Our recent result is the demonstration of a subharmonic system with a two-octave spectrum, 3 – 12 μm, which covers vibrational resonances for most molecular species. Potentially, through frequency division in the coherent subharmonic optical parametric amplifier regime, this method can be used to obtain intense long-wavelength pulses for high-field physics applications.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"2007 1","pages":"307 - 312"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86207829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonghwan Kim, S. Park, E. Sall’, G. Kim, V. Yashin, J. Yang
Nonlinear effects in a high-power laser amplification system based on thin-rod active elements are experimentally investigated. It is shown that the most important nonlinear effect is the Kerr effect leading to self-focusing and self-phase modulation of laser radiation. The observed luminescence in Yb : YAG crystals in the visible region of the spectrum is caused by the charge transfer luminescence effect, which, in turn, is due to multiphoton absorption of laser radiation. Second-order nonlinearity in the crystal is used to effectively convert femtosecond pulses to second harmonic and sum-frequency waves which exhibit radiations of green and UV spectra.
{"title":"Nonlinear phenomena in femtosecond laser systems based on Yb: YAG thin-rod amplifiers","authors":"Jonghwan Kim, S. Park, E. Sall’, G. Kim, V. Yashin, J. Yang","doi":"10.1070/qel18024","DOIUrl":"https://doi.org/10.1070/qel18024","url":null,"abstract":"Nonlinear effects in a high-power laser amplification system based on thin-rod active elements are experimentally investigated. It is shown that the most important nonlinear effect is the Kerr effect leading to self-focusing and self-phase modulation of laser radiation. The observed luminescence in Yb : YAG crystals in the visible region of the spectrum is caused by the charge transfer luminescence effect, which, in turn, is due to multiphoton absorption of laser radiation. Second-order nonlinearity in the crystal is used to effectively convert femtosecond pulses to second harmonic and sum-frequency waves which exhibit radiations of green and UV spectra.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"16 1","pages":"313 - 321"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73729621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have investigated a multipass Yb : KGW disk amplifier based on the White cell configuration and pumped by a laser diode with a fibre output. It is shown that the three-mirror layout of the cell is three times more efficient than the four-mirror one, since the size and position of the signal beam on the surface of the active element do not depend on the cell number of passes. For a three-mirror cell scheme, a small-signal gain G = 168 is obtained in experiments for a pump power of 360 W. The experimentally achieved gain of two such amplifiers arranged in series is 6 × 104, which exceeds G 2 approximately two-fold.
{"title":"Multipass Yb : KGW disk amplifier","authors":"A. Potemkin, M. Martyanov, S. Mironov","doi":"10.1070/qel18026","DOIUrl":"https://doi.org/10.1070/qel18026","url":null,"abstract":"We have investigated a multipass Yb : KGW disk amplifier based on the White cell configuration and pumped by a laser diode with a fibre output. It is shown that the three-mirror layout of the cell is three times more efficient than the four-mirror one, since the size and position of the signal beam on the surface of the active element do not depend on the cell number of passes. For a three-mirror cell scheme, a small-signal gain G = 168 is obtained in experiments for a pump power of 360 W. The experimentally achieved gain of two such amplifiers arranged in series is 6 × 104, which exceeds G 2 approximately two-fold.","PeriodicalId":20775,"journal":{"name":"Quantum Electronics","volume":"91 1","pages":"332 - 339"},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72711998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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