共查询到20条相似文献,搜索用时 31 毫秒
1.
E. Yu. Loktionov A. V. Ovchinnikov Yu. Yu. Protasov D. S. Sitnikov 《Bulletin of the Lebedev Physics Institute》2010,37(3):82-84
Optical gas-dynamic processes occurring in polymeric targets ((CH2O)
n
, (C2F4)
n
) exposed to ultrashort laser pulses (τ
0.5 ∼ 45 − 70 fs; λ
I,II,III
= 266, 400, 800 nm; and E/S ∼ 0.1 − 40 J/cm2 at r
0 ∼ 20 μm) were studied under normal conditions and in vacuum (p ∼ 10−2 Pa). The dynamics of the mass flow from the target surface (m′ ∼ 10−5 − 10−4 g/J) was studied and the spectral-energy thresholds of laser ablation, the electron density distribution (n
e
∼ 1014 − 1018 cm−3), the mass-averaged velocity of the material flow from the target surface (∼ 103 m/s), and the chemical composition and average temperature in the near-surface plasma formation (T ∼ 5000 K) were determined using interference microscopy, emission spectroscopy, and shadowgraphy. 相似文献
2.
Y. B. Kale A. Ray R. D’Souza Q. V. Lawande B. N. Jagatap 《Applied physics. B, Lasers and optics》2010,100(3):505-514
We here present a comparative study of frequency stabilities of pump and probe lasers coupled at a frequency offset generated
by coherent photon-atom interaction. Pump-probe spectroscopy of the Λ configuration in D2 transition of cesium is carried out to obtain sub-natural (∼2 MHz) electromagnetically induced transparency (EIT) and sub-Doppler
(∼10 MHz) Autler-Townes (AT) resonance. The pump laser is locked on the saturated absorption spectrum (SAS, ∼13 MHz) and the
probe laser is successively stabilized on EIT and AT signals. Frequency stabilities of pump and probe lasers are calculated
in terms of Allan variance σ(2,τ) by using the frequency noise power spectrum. It is found that the frequency stability of the probe stabilized on EIT is
superior (σ∼2×10−13) to that of SAS locked pump laser (σ∼10−12), whereas the performance of the AT stabilized laser is inferior (σ∼6×10−12). This contrasting behavior is discussed in terms of the theme of conventional master-slave offset locking scheme and the
mechanisms underlying the EIT and sub-Doppler AT resonances in a Doppler broadened atomic medium. 相似文献
3.
4.
G. G. Kozlov V. S. Zapasskii Yu. V. Kapitonov V. V. Ovsyankin 《Optics and Spectroscopy》2011,110(3):425-431
The effect of the light group velocity reduction in dielectric Bragg reflection waveguide structures (SiO2/TiO2) in the vicinity of the cutoff frequency is studied experimentally. The effect of anti-mirror reflection specific to Bragg
reflection waveguides is described and employed to detect slow light. Experiments were performed using Ti:sapphire laser pulses
∼100 fs in length. The group index n
g
∼ 30 with a fractional pulse delay (normalized to the pulse width) of ∼10 is demonstrated. The problems and prospects of
the implementation of slow-light devices based on Bragg reflection waveguide structures are discussed. 相似文献
5.
T. C. He C. S. Wang X. Pan C. Z. Zhang G. Y. Lu 《Applied physics. B, Lasers and optics》2009,94(4):653-659
A novel azobenzene-containing fluorinated polyimide was synthesized. The nonlinear optical property and photoinduced birefringence
of a polyimide thin film were investigated. Large third-order nonlinear refraction (n
2=−4.49×10−11 cm2/W) was observed in the polyimide thin film by carrying out Z-scan measurement. The polyimide thin film exhibited larger nonlinear
refraction than that of a mono-azo dye doped PMMA thin film (n
2=−1.63×10−12 cm2/W). The photoinduced birefringence of the polyimide thin film (▵
n∼10−2) under different pump intensities was investigated; it was much larger than that of the mono-azo dye doped PMMA thin film
(▵
n∼10−3). Moreover, the time constants for birefringence growth and relaxation processes were determined. 相似文献
6.
I. M. Batyaev 《Journal of Applied Spectroscopy》1997,64(5):620-632
An attempt was made to describe and show the possibilities of new inorganic neodynium- and uranium-activated laser liquids:
SO2-GaCl3-NdCl4; SO2Cl2-GaCl3-NdCl3-UO2Cl2; POCl2-MCln-NdCl3-UO2Cl2 for development and synthesis of direct nuclear reaction-excited lasers. Luminescence data presented in the work were used
to calculate the luminescence parameters of the laser liquids such as oscillator strengths f, probability of spontaneous radiation
A, intermultiplet luminescence branching coefficient β, cross-section for induced radiation σ, luminescence decay time τ,
quantum yield η, and others. It is shown that the oscillator strengths of the normal absorption bands of Na3+, which play the main part in the pumping processes, exceed the oscillator strengths of Na3+ for aqueous and many other nonaqueous systems. In the luminescence excitation spectra of the Na3+ ion, bands are isolated in the range 400–1000 nm atλ
rec
=1.06 μm. With excitation, luminescence occurs through the4F3/2→4I9/2,11/2.13/2 channels. Luminescence spectral data are related to the lasing parameters. The threshold lasing energy is∼18 J/cm3. For a resonator with mirros h1=100% and h2=20, 40, 56, and 80%, the lasing energy is∼20–120 MJ/cm3 in the pumping energy range 18–180 J/cm3. The differential efficiency is ∼0.2% The substantial angular radiation divergence (θ∼4·10−2 rad) and strong thermostatic distortions that occur in the active element (dn/dT≈−1.9·10−4K−1) are a disadvantage of laser liquids. It is shown that operation of neodymium- and uranium-activated inorganic liquid lasers
is stable under the present conditions.
A. I. Gertsen Russian State Pedagogical University, Moika Embankment, 48, St. Petersburg, 191186, Russia. Translated from
Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 607–619, September–October, 1997. 相似文献
7.
E. Yu. Loktionov A. V. Ovchinnikov Yu. Yu. Protasov Yu. S. Protasov D. S. Sitnikov 《Journal of Applied Spectroscopy》2012,79(1):104-112
We present the results of an experimental study of the ablation spectral energy thresholds for a number of polymer materials
((C2F4)
n
, (CH2O)
n
) exposed to femtosecond (τ0.5 ~ 45–70 fs) laser pulses (λ ~ 266, 400, 800 nm) under atmospheric conditions and under vacuum (p ~ 10–2 Pa). We have analyzed the energy thresholds and the efficiency of optical, thermophysical, and gasdynamic processes
in laser ablation vs. the laser pulse duration and photon energy. 相似文献
8.
V. M. Gordienko I. A. Makarov V. P. Petukhov A. S. Khomenko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(2):183-188
The dependence of the characteristic X-ray radiation yield from CaF2 crystal on the formed microchannel depth under highly intensive (I ∼ 3 × 1015 W/cm2) laser pulses with different contrast was obtained. The maximum of the characteristic X-ray radiation yield at these experimental
conditions corresponded to the microchannel depth of 30–50 μm. The efficiency of the laser radiation conversion to the characteristic
X-ray radiation increased from 6 × 10−8 for the surface up to 10−7 in the microchannel. The dependence of the characteristic X-ray radiation yield on the viewing angle showed that the source
of X-ray radiation was located near the surface inside the microchannel. 相似文献
9.
10.
The total (p, n) reaction cross section for48Ca has been measured as a function of proton energy in the energy range 1.885 to 5.100 MeV with an overall resolution of ∼
2 keV and in ∼ 5 keV energy steps. The fluctutions in fine resolution data have been analysed to determine the average coherence
width 〈Γ〉. The excitation function averaged over large energy intervals has been analyzed in terms of the optical model. The
isobaric analogue resonances atE
p
∼ 1.95 and 4 MeV have been shape-analyzed to extract the proton partial width and the spectroscopic factorS
n
. A comparison of the gross structures observed in ∼ 55 keV averaged excitation function with the predictions of Izumo’s partial
equilibrium model has also been made. 相似文献
11.
C. Herberg M. Ostrick H.G. Andresen J.R.M. Annand K. Aulenbacher J. Becker P. Drescher D. Eyl A. Frey P. Grabmayr S.J. Hall P. Hartmann T. Hehl W. Heil J. Hoffmann D. Ireland J.D. Kellie F. Klein K. Livingston Ch. Nachtigall A. Natter E.W. Otten R.O. Owens E. Reichert D. Rohe H. Schmieden R. Sprengard M. Steigerwald K.-H. Steffens Th. Walcher R. Watson 《The European Physical Journal A - Hadrons and Nuclei》1999,5(2):131-135
The electric form factor of the neutron G
E,n has been determined at the Mainz Microtron MAMI at the low momentum transfer Q
2= 0.15 (GeV/c)2 in a measurement of the recoil polarisation ratio P
x/Pz in the quasifree reaction D(e,e′n)p. At this Q
2 the influence of the nuclear binding is strong. A purely kinematical model is used to get some insight into the effect of
the initial Fermi momentum distribution of the neutron. The influence of the final state interaction is determined quantitatively
by a model of Arenh?vel et al.. After the corresponding corrections a value of G
E,n(0.15 (GeV/c)2) = 0.0481±0.0065stat±0.0053syst is obtained.
Received: 12 April 1999 相似文献
12.
A continuous-wave laser with line-shaped end-pumping profile operating at 912 nm is presented. The maximum output power of
7.82 W is obtained, with a slop efficiency of 24.7% and beam quality factors of M
x
2 ∼ 20, M
y
2 ∼ 1.3. To the best of our knowledge, this is the first laser diode bar directly pumped Nd:GdVO4 slab laser based on the quasi-three-level 4
F
3/2 → 4
F
9/2 transition in neodymium. Furthermore, we disclose that the experimental setups can be improved by inserting a plano-concave
cylindrical lens in the cavity to form a new quasi-concentric resonator to improve die mode-matching in x-direction. 相似文献
13.
Wen-Xian Li Yu-Shan Zheng Xiao-Jun Sun Xiao-Yan Shi Wen-Juan Chai Tie Ren 《Journal of fluorescence》2010,20(1):235-241
A ligand with double sulfinyl groups, naphthyl-naphthalinesulphonylpropyl sulfoxide(dinaphthyl disulfoxide, L), was synthesized
by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity,
coordination titration analysis, IR, TG-DTA, 1HNMR and UV spectra. The composition of these complexes, were RE2(ClO4)6·(L)5·nH2O (RE = La, Nd, Eu, Tb, Yb, n = 2 ∼ 6, L = C10H7SOC3H6SOC10H7). The fluorescent spectra illustrated that the Eu (III) complex had an excellent luminescence. It was supposed that the ligand
was benefited for transferring the energy from ligand to the excitation state energy level (5D0) of Eu (III). The Tb (III) complex displayed weak luminescence, which attributed to low energy transferring efficiency between
the average triplet state energy level of ligand and the excited state (5D4) of Tb (III). So the Eu (III) complex displayed a good antenna effect for luminescence. The phosphorescence spectra and the
relationship between fluorescence lifetime and fluorescence intensity were also discussed. 相似文献
14.
V. D. Zvorykin A. O. Levchenko A. G. Molchanov I. V. Smetanin N. N. Ustinovskii 《Bulletin of the Lebedev Physics Institute》2010,37(2):60-64
The grazing mode of microwave propagation in a hollow plasma waveguide formed by ionization of atmospheric air with a small
easily ionized additive by strong UV pulses of the Garpun KrF laser (λ = 248 nm, the pulse duration and energy are ∼70 ns and ∼50 J) was experimentally demonstrated for the first time. The annular
laser beam produced a hollow tube ∼10 cm in diameter with an electron density of ∼1012 cm−3 in a plasma wall ∼1 cm thick, over whichmicrowave radiation with λ
mw
∼ 8 mm was transmitted to a distance of 60 m. Themicrowave signal transmitted by the waveguide was amplified by a factor
of 6 in comparison with propagation in free space. 相似文献
15.
V. A. Andronov S. A. Bel’kov A. V. Bessarab I. N. Voronich S. G. Garanin A. A. Gorbunov V. N. Derkach G. V. Dolgoleva A. I. Zaretskii V. M. Izgorodin B. N. Ilyushechkin G. A. Kirillov G. G. Kochemasov Yu. V. Kuratov V. I. Lazarchuk V. A. Lebedev V. M. Murugov L. S. Mkhitar’yan A. V. Okutin S. I. Petrov A. V. Pinegin N. N. Rukavishnikov A. N. Razin A. V. Ryadov A. V. Senik N. A. Suslov S. A. Sukharev V. A. Tokarev 《Journal of Experimental and Theoretical Physics》1997,84(3):485-488
The results of the first experiments devised to investigate the mixing of thin layers of Al and Au during the laser acceleration
of flat three-layer targets of Si (5 μm), Al (2 μm), and Au (0.05–0.26 μm) by radiation converted to the second harmonic from the Iskra-4 iodine laser with an intensity of 4×1013−7×1013 W/cm2 (τ
0.5∼1 ns), which acts on the Si side of the target. A method for detecting the occurrence of mixing is developed. It is established
that under the experimental conditions the thickness of the mixing region is at least ∼0.15 μm. The results of a theoretical analysis of the evolution of the disturbances leading to mixing are presented.
Zh. éksp. Teor. Fiz. 111, 882–888 (March 1997)
Deceased. 相似文献
16.
V. S. Belyaev A. P. Matafonov S. M. Ribakov V. P. Krainov V. S. Lisitsa V. P. Andrianov G. N. Ignat’ev A. S. Rusetskiy 《Laser Physics》2011,21(8):1398-1403
The experimental results on the initiation of various (γ, n) and (p, n) nuclear reactions in the picosecond laser plasma are presented. It is demonstrated that the following (γ, n) and (p, n) nuclear reactions can be initiated at a laser intensity of 2 × 1018 W/cm2 with the threshold energies of γ-quanta ranging from 1.67 to 7.56 MeV and the threshold energies of protons ranging from 1.88 to 5 MeV: 9Be(γ, n)2α, 181Ta(γ, n)180Ta, 7Li(p, n)7Be, 63Cu(p, n)63Zn, 48Ti(p, n)48V. The method based on the detection of fast neutrons using the 3He counters is employed for the measurement of the number
of the initiated (γ, n) and (p, n) nuclear reactions. The measured yield of the (γ, n) and (p, n) nuclear reactions ranges from 5 × 101 to 105 reactions per laser pulse. 相似文献
17.
The mechanism of generation of terahertz radiation upon irradiation of a target by short (∼ 0.1 ns) high-intensity laser pulses
(I ∼ 1018−1019 W cm−2) is investigated by numerical simulation using the relativistic electromagnetic PIC code. The interaction of such a pulse
with the target, a plasma is formed on it. Electrons emitted from the plasma form a virtual cathode whose oscillations are
determined not only by their self-field, but also by the field of ions of the plasma. Generation occurs in the terahertz frequency
range with the efficiency thrice as high as in the absence of ions (i.e., with traditional reditron generation mechanism).
The explanation for this effect is also given. 相似文献
18.
S. K. Zhang K. Sugioka J. Fan K. Toyoda S. C. Zou 《Applied Physics A: Materials Science & Processing》1994,58(2):191-195
Excimer laser doping of GaAs using sulphur adsorbate as a dopant source is demonstrated. Box-like n-type layers of depths of about 100 nm with carrier concentration as high as (23)×1019 cm–3 are formed. Passivation of GaAs using a (NH4)2Sx solution for 40 min followed by sublimation of the excess sulphur atoms in high vacuum result in an effective dopant for controllable n-type doping. The samples are irradiated using a KrF excimer laser in a N2 gaseous environment. Secondary ion mass spectrometry (SIMS) measurements show that sulphur is successfully incorporated in the GaAs. The sheet resistance is controlled by adjusting the laser energy fluence and number of laser pulses. Rutherford backscattering spectrometry with channeling (RBS/C) alignment measurement indicates that lattice damage is undetectable for N2 gas pressures of 760 Torr. 相似文献
19.
L. I. Kuznetsov 《Technical Physics》1997,42(3):304-308
Experimental investigations have been carried out to measure the transmission coefficient of laser light through an erosion
flare, the coefficient of reflection from the irradiated solid surface, and the recoil momentum of insulating and metal targets
in the range of pulsed laser intensities from 106 to 107 W/cm2 with variation in the pressure of the surrounding medium from 10−2 to 105 Pa. An analysis is made of how the screening properties of the erosion flare affect the recoil momentum, and it is found
necessary to take into account absorption of the radiation in the flare in determining the coefficient of reflection of the
radiation from the surface.
Zh. Tekh. Fiz. 67, 58–62 (March 1997) 相似文献
20.
T. G. Adiks A. F. Bunkin V. A. Luk’yanchenko S. M. Pershin 《Physics of Wave Phenomena》2008,16(1):1-6
The contribution of impurity fluorescence was determined in the water Raman spectra excited by the second harmonic (λ = 532 nm) of a pulsed Nd:YAG laser. Water samples prepared by different techniques (tap water (undistilled), distilled water,
Milli-Q water, water for injections, and water subjected to cavitation treatment) were investigated. The Raman (bands at ν
2 ∼ 1550 cm−1 and ν
3 ∼ 3400 cm−1) and fluorescence (Stokes shift 2500 cm−1) signals were separated spectrally and according to the differences in the emission kinetics. It was established that all
investigated samples, including distilled and specially purified water for injections, exhibit afterglow. The highest sensitivity
to the presence of impurities was revealed near ∼ 2500 cm−1. The least contribution to the fluorescence signal was found in the water for injections. 相似文献