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1.
Based on equations for the evolution of the polarization density matrix for laser emission, we have shown that when a laser
with an anisotropic cavity is turned on in a magnetic field higher than some critical value, we will observe a new optical
effect: pulsations between the polarized and completely unpolarized states of the laser emission. In a magnetic field much
higher than the critical value, practically complete suppression of polarization occurs, which may serve as a method for obtaining
unpolarized laser emission.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 134–142, January–February, 2008. 相似文献
2.
In the presence of an external Aharonov–Bohm potential, we investigate the two QED processes of the emission of a bremsstrahlung
photon by an electron, and the production of an electron–positron pair by a single photon. Calculations are carried out using
the Born approximation within the framework of covariant perturbation theory to lowest non-vanishing order in α. The matrix
element for each process is derived, and the corresponding differential cross-section is calculated. In the non-relativistic
limit, the resulting angular and spectral distributions and some polarization properties are considered, and compared to results
of previous works. 相似文献
3.
A. G. Ushenko S. B. Ermolenko D. N. Burkovets Yu. A. Ushenko 《Journal of Applied Spectroscopy》2000,67(1):65-69
A matrix method is proposed for describing polarization properties of biological tissues as an aggregate of uniaxial crystal
structures. We investigated 25 μm-thick histological sections of compact bone tissue which provided single light scattering.
It is shown that in this case there exists a unique relationship between the polarization parameters of the boundary laser
field and the parameters of anisotropy and orientation of the structural elements of biological tissue. On this basis, contactless
methods of laser polarimetry of histological sections of bone tissue have been proposed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 52–55, January–February, 2000. 相似文献
4.
Using DCM dye grains and light of different wavelengths generated by two CW laser diodes that oscillate in the near-infrared
wavelength region, visible light emission from dye grains due to near-infrared excitation based on a nonadiabatic, nondegenerate
excitation process was observed for the first time. Unlike sum-frequency generation with nonlinear polarization, the difference
in polarization angles of the two beams did not affect the emitted light intensity. Optical sampling based on this nonadiabatic,
nondegenerate excitation principle was demonstrated for the first time. The optical pulse shape in the wavelength band of
λ=1250–1350 nm, which is close to the wavelength range used for optical fiber communications, was measured with a temporal
resolution of 0.8–1.1 ps. 相似文献
5.
We have shown that brief exposure of sturgeon embryos (fertilized roe) in the organogenesis stage to low-intensity radiation
in the visible region of the spectrum can have a long-term effect on embryonic and post-embryonic development of the fish,
detectable 50 days after the irradiation procedure. The biological effects (size-weight characteristics and hardiness parameters
of the fish relative to unfavorable habitat conditions) induced by linearly polarized emission from a monochromatic laser
source (helium-neon laser, λ = 632.8 nm, Δλ ≈ 0.02 nm) and a quasi-monochromatic light-emitting diode (LED) source (maximum
in emission spectrum λ = 631 nm, Δ λ = 15 nm) are practically the same. Going to broadband linearly polarized radiation (λ
= 420–800 nm) is accompanied by a decrease in the biological effect.
From the results of studies of the effect on embryos from linearly polarized and unpolarized radiation from an LED source
and also the effect of linearly polarized, circularly polarized, and unpolarized radiation from a helium-neon laser, we concluded
that the type of polarization is of critical importance in realization of the biological effect of radiation. In this case,
the maximum stimulating effect (on the size×weight characteristics and the hardiness parameters for juvenile fish) is observed
on exposure to linearly polarized radiation; the photobiological effect induced in the same dose range by light with natural
polarization (i.e., unpolarized) is significantly less pronounced; the stimulating effect of circularly polarized radiation
occupies an intermediate position.
Based on the presented data and also on data obtained previously, we conclude that among the resonant and nonresonant photophysical
processes (orientational effect of light, effect of gradient forces, dipole-dipole interactions, thermooptic processes) capable
of inducing photobiological effects dependent on such laser-specific characteristics as polarization and coherence, the determining
influence in the processes studied in this work comes from the orientational effect of light and dipole×dipole interactions.
And the orientational effect can appear for anisotropic media with liquid-crystal type ordering (especially domains in membranes
and multiple-enzyme complexes) both under conditions when there is no resonant absorption and for weakly absorbing structures,
and can initiate a change in their conformations and accordingly their functional characteristics.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 843–858, November–December, 2008. 相似文献
6.
L. I. Burov A. S. Gorbatsevich A. G. Ryabtsev G. I. Ryabtsev A. N. Imenkov Yu. P. Yakovlev 《Journal of Applied Spectroscopy》2008,75(6):805-809
The spatial distribution of emission intensity in the active layer of a laser diode (LD) based on an InAsSb/InAsSbP heterostructure
(generation wavelength λgen ∼ 3.3 μm) is obtained for various stripe widths w by means of numerical solution of the wave equation in the 2D approximation
taking into account the refractive index nonlinearity. It has been shown that the special distribution of emission intensity
becomes strongly inhomogeneous at w values exceeding 9–10 μm, which results in the appearance of additional maxima in the
far-field pattern. Calculated far-field patterns in the active layer plane of the LD agree with corresponding experimental
data.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 804–808, November–December, 2008. 相似文献
7.
V. E. Shaposhnikov V. V. Kocharovskii V. V. Kocharovskii H. P. Ladreiter H. O. Rucker V. V. Zaitsev 《Radiophysics and Quantum Electronics》1998,41(2):115-124
Jovian decameter emission is known to exhibit almost total polarization. We consider the elliptical polarization to be a consequence
of linear-mode coupling in the Jovian magnetosphere outside the source region. We determine conditions of emission propagation
along the ray path that are necessary for self-consistent explanatation of the polarization observations and show that the
ellipticity (axial ratio of the polarization ellipse) is determined by the magnetospheric plasma density ne in a small region a distance of about half the Jovian radius from the radiation source. The plasma density in the region
is quite low, ne<0.4 cm−3, and the geometrical-optics approximation of emssion propagation in front of the region converts to the vacuum approximation
behind it. The latter means that the linear-mode coupling in the Jovian inner magnetosphere is manifested as the effect of
limiting polarization. Sources of decameter emission emitting at different frequencies f are located at heights corresponding
to gyrofrequency levels f
Be
≅f and at magnetic-force lines that belong to L-shells passing through the satellite Io. The location of the transitional
region in the Jovian magnetosphere varies depending on the emission frequency and the time. For each given decameter radio
emission storm occupying some region in frequencytime space, we have a number of transitional regions located in a certain
region of the Jovian magnetosphere—the interaction region of the magnetosphere (IRM) for the given emission storm. The distribution
of magnetospheric plasma in an IRM is found from data of observations of the polarization ellipiicity of the given decameter
radio emission storm. By matching the calculated ellipticity of emission with the observed ellipticity at every point of frequency-time
space of the emission dynamic spectrum one finds a recurrent relation between the local values of the magnetospheric plasma
density Nc and the planetary magnetic field B in the IRM, which allows evaluation of the distribution of plasma density if a definite
model of the Jovian magnetic field has been adopted.
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia; Space Research Institute, Austrian Academy
of Sciences, Austria. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 2, pp. 177–193, February,
1998. 相似文献
8.
The beam propagation factor, M2 of the master-oscillator power-amplifier (MOPA) CuBr laser emission compliant with ISO 11146 is studied methodically. Statistical
parameters of 2D intensity profile of the near and far fields of MOPA laser radiation are measured by a beam analyzing technique
as functions of timing delay between MO and PA. For first time the influence of the gas buffer (causing the radiation profile
to change from annular to top-hat and Gaussian-like) and light polarization on CuBr laser beam focusability (M2) was under investigation. The MOPA gain curve is found and the influence of gain on the input signal (from MO into PA) due
to the absorption/amplification in PA on the field profiles is shown. For annular radiation M2 range is from 13–14 (small delays) to 5–6 (large delays) and for filled-center radiation M2 is 6–7 (small delays) and at the end of gain curve is as much as 4. With polarized light, M2 drops to 3 at the end of gain curve. The brightness of laser emission with hydrogen goes up 3–5 times and the linearly-polarized
beam is at least 40% brighter than that of partial or non-polarized beams. 相似文献
9.
Thomas Lehecka Andrew Mostovych Jeffrey Thomas 《Applied Physics A: Materials Science & Processing》2008,92(3):727-741
Time resolved emission from the interaction of ultra-short (∼200 fs) laser pulses with aluminum and copper targets was investigated.
Measurements show that emission from the laser produced plasma in air is significantly more intense than in near vacuum conditions
and that the emission in air can extend for periods exceeding 100 ns. Modeling the laser–target–air coupling shows that the
laser–target interaction can lead to blast wave shock waves being launched in the ambient air and that the emission from the
shocked air dominates over emission from the target surface. The long term emission measurements in air are in agreement with
the modeling results. 相似文献
10.
Distributed feedback (DFB) lasing in permanent volume transmission gratings formed in a laser dye-doped organic–inorganic
nanocomposite has been investigated. DFB laser cavities were fabricated using one-step two-beam holographic exposure of Pyrromethene
567 (PM567) doped photopolymerizable acrylate monomers containing inorganic (LaPO4) nanoparticles. Compared to the formulation previously utilized, the material composition presented provides longer lifetime
of the laser. Spectral and polarization properties, input–output and stability characteristics of the laser output have been
investigated by varying the material composition and the patterning parameters. DFB lasing emission of the second and the
third diffraction orders has been demonstrated. The spectral linewidth of ∼0.08 nm has been observed at a pump energy threshold
of about 0.2 μJ/pulse for the second-order DFB lasing when pumped with 532 nm 500 ps laser pulses. Spectral tuning of the
lasing output over ∼56 and ∼7 nm was obtained by varying the grating period and the content of inorganic nanoparticles in
the polymer matrix, respectively. 相似文献
11.
Y. Yan B. Li K. Liu Z. Dong S. Qian W. Li X. Wang 《Applied physics. B, Lasers and optics》2007,87(2):249-254
A comparative study of the nonlinear optical properties and ultrafast dynamics of three oligomers were carried out using femtosecond
laser spectroscopic techniques. All oligomers showed intense fluorescence emission induced by a two-photon absorption process.
Relaxation features with parallel and perpendicular polarization configurations were investigated in a one-color pump–probe
experiment at 400 nm. Two relaxation components were assigned to the exciton migration and exciton recombination processes,
respectively. Time-resolved fluorescence results showed that the electron–phonon interaction happens on the picosecond-scale,
while the recombination lifetimes of the excited state are relatively long.
PACS 33.80.Rv; 34.30.+h; 82.53.-k; 82.35.Ej 相似文献
12.
We have experimentally studied the characteristic features of a laser beam, polarized at angles of ± 45° to the horizontal
(vertical), passing through plates of varying thickness cut from a CdP2 crystal and placed between crossed polarizers, as a function of their angle of rotation relative to the vertical axis. We
show that a periodic variation in the intensity is connected with the variation in polarization of the laser beam. We have
established that the laser beam remains linearly polarized not only when it passes through the sample along the optic axis,
but also when it travels at up to a 17.5° angle to the optic axis. In this case, the specific rotation of the plane of polarization
along the optic axis is 68.2 degrees/mm for a thicker plate and 83.3 degrees/mm for a thin plate.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 690–693, September–October, 2006. 相似文献
13.
M. Jiménez de Castro J. M. Fernández Navarro 《Applied physics. B, Lasers and optics》2012,106(3):669-675
The infrared optical properties of Er3+ ions are reported for 60GeO2–20PbO–20Na2O glass for two Er2O3 concentrations. From the optical absorption spectra, the Judd–Ofelt (J–O) parameters have been obtained and have been used
to calculate radiative lifetimes and stimulated emission cross sections. A narrow emission band peaked at 1536 nm with exponential
decay for both Er concentrations is observed. The measured lifetime decreases for increasing Er concentration, its value being
very close, in the case of the lowest doping level, to the radiative lifetime calculated from J–O analysis. This, together
with the relatively high emission cross section makes this glass suitable for laser applications. 相似文献
14.
V. A. Dlugunovich 《Journal of Applied Spectroscopy》1999,66(5):719-725
The degree and azimuth of polarization and the indicatrix of the intensity of radiation (λ=0.63 μm) reflected by the surface
of a monodirectional superhigh-modulus organoplastic material after structural transformations induced in it by CO2-laser radiation are measured. It is shown that the space-polarization characteristics of the radiation reflected by the organoplastic
material charred as a result of laser heating correspond to the parameters of radiation scattered by a nontransparent material
with an isotropic surface in the approximation of geometrical optics.
B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 635–639, September–October, 1999. 相似文献
15.
We generalize the joint time–frequency von Neumann representation of femtosecond laser pulses for usage with time-dependent
polarization states. The electric field is expanded in terms of Gaussian-shaped transform-limited subpulses located on a discrete
time–frequency lattice, each with a specific polarization state. This formalism provides an intuitive picture for the time-
and frequency-dependent polarization state. It can also serve as a basis for polarization pulse shaping. As an illustration,
we define pulses for which polarization parameters (ellipticity and orientation) are given directly in time–frequency phase
space. This approach has applications in quantum control and other areas for which time- and frequency-dependent light polarization
is relevant. 相似文献
16.
S. A. Bakhramov A. M. Kokhkharov U. K. Makhmonov O. R. Parpiev P. K. Khabibullaev 《Journal of Applied Spectroscopy》2009,76(1):82-88
We have experimentally studied for the first time the effect of photoinduced rotation of the plane of polarization for pulsed
laser radiation in solutions of C70 fullerene in organic solvents and their mixtures. We have shown that the effect is observed for elliptical polarization of
the laser radiation and is absent for linear polarization. We present the results of a study of the nonlinear optical characteristics
of the C70 solutions. We discuss the physical mechanisms by which nonlinear gyrotropy is induced in solutions.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 93–99, January–February, 2009. 相似文献
17.
A. V. Kuptsova 《Journal of Applied Spectroscopy》2000,67(1):77-81
The spectra of Faraday rotation of the plane of polarization of laser radiation in strong radiation fields and a magnetic
field were investigated for alkali atoms. The spectra were obtained using the known method of computer simulation of polarization
effects in real multilevel atoms. The possibility of using these effects in the phase-polarization method of selection of
laser frequencies was considered.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 61–64, January–February, 2000. 相似文献
18.
研究发现,在超强激光作用下电子运动的相对论效应可导致高次谐波辐射,采用单电子模型计算分析了不同偏振微光作用下的高次谐波发射,表明圆偏振激光较线偏振激光更有利于高次谐波产生。 相似文献
19.
Probing vacuum birefringence by phase-contrast Fourier imaging under fields of high-intensity lasers
In vacuum high-intensity lasers can cause photon–photon interaction via the process of virtual vacuum polarization which may
be measured by the phase velocity shift of photons across intense fields. In the optical frequency domain, the photon–photon
interaction is polarization-mediated described by the Euler–Heisenberg effective action. This theory predicts the vacuum birefringence
or polarization dependence of the phase velocity shift arising from nonlinear properties in quantum electrodynamics (QED).
We suggest a method to measure the vacuum birefringence under intense optical laser fields based on the absolute phase velocity
shift by phase-contrast Fourier imaging. The method may serve for observing effects even beyond the QED vacuum polarization. 相似文献
20.
Laser action was generated in dye-doped sol–gel glass waveguides and in liquid solutions by crossing two beams from a frequency-doubled
neodymium:YAG laser. The angle between the polarization directions of the two beams was varied continuously from 90. The case
of 0° corresponded to pure intensity modulation. As the angle increased, the degree of intensity modulation decreased, resulting
in the decline and finally the demise of the laser output. At 90°, corresponding to pure polarization modulation, distributed
feedback laser action with narrow line-width output was again observed when the pump energy was increased three-fold. The
laser output also showed different polarization characteristics when the feedback mechanism was changed from intensity modulation
to polarization modulation.
Received: 13 February 2003 / Revised version: 3 April 2003 / Published online: 22 May 2003
RID="*"
ID="*"Corresponding author. Fax: 852/2603-5204, E-mail: dlo@sun1.phy.cuhk.edu.hk 相似文献