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1.
V. Kubeček K. Hamal I. Procházka R. Buzelis V. Girdauskas A. Dementiev 《Czechoslovak Journal of Physics》1991,41(8):733-742
There is a continuous effort to generate stable, powerful picosecond laser pulses for application in spectroscopy, nonlinear optics and parametric light generation, as well. One of the possible methods is the compression of longer nanosecond laser pulses by stimulated Brillouin and stimulated Raman scattering. The advantages of such a technique, in comparison to the used mode locked picosecond lasers, are as follows: the absence of the active and/or passive mode lockers used to generate a train of picosecond pulses, and the absence of a fast electrooptical shutter used to select a single pulse from a train of pulses. The application of stimulated Brillouin and stimulated Raman scattering permits to generate picosecond pulses in the wavelength regions not covered by mode locked lasers. Of special interest is the wavelength region of 0·8 m, which may be amplified by the attractive Titanium Sapphire lasers. In this paper we are summarizing our results in theoretical modelling and in real generation of picosecond pulses by means of cascaded stimulated Brillouin and Raman scattering. The models of scattering processes have been investigated. The stable generation of 5, 7, 3 picosecond pulses have been optimized for the wavelengths of 0·8, 0·64 and 0·54 m, respectively. In all these cases, the pulses exhibited the far field pattern close to Gaussian, with the pulse energy ranging from 0·2 to 1 mJ. 相似文献
2.
The random distributed feedback fiber laser operating via the stimulated Raman scattering and random distributed feedback
based on the Rayleigh scattering is demonstrated in the 1.2 μm frequency band. The RDFB fiber laser generates at 1174 nm up
to 2.4 W of output power with corresponding slope efficiency more than 30%. The output radiation has the spectral shape similar
to the conventional Raman fiber lasers and spectral width less than 1.7 nm. 相似文献
3.
A.A. Kaminskii S.N. Bagayev J. Hulliger H. Eichler J. Findeisen R. Macdonald 《Applied physics. B, Lasers and optics》1998,67(2):157-162
3 crystal were investigated. At room temperature under picosecond excitation efficient high-order stimulated Raman scattering
in the visible and near-IR regions was observed. A total conversion efficiency of the 1-μm Nd3+:Y3Al5O12 laser-pump emission to Stokes and anti-Stokes lines of about 70% was estimated. All registered scattered laser components
were identified. We classify the NaClO3 single crystal as a promising χ(3) medium for Raman lasers.
Received: 14 January 1998 相似文献
4.
Physical principles, new ways and means of creation, schemes, characteristics and features of efficient high-power tunable
pulse Raman lasers, operating in the near and middle ir are reviewed. The paper includes: tunable dye and Nd lasers as pump
sources; promising active media and their optimal excitation methods; optical systems for producing spatially homogeneous
pumping; the physics of Raman oscillators and their practical schemes, efficient high pulse energy liquid N2 and compressed H2 Raman oscillators, covering several bands in the range between 1.4 and 9.2 μm; the physics and construction of efficient
tunable Raman amplifiers-convertors, amplifying in the saturation regime of spontaneously scattered or beforehand produced
and collimated external Stokes signals, obtained in the spectral range between 0.83 μm and 18 μm. Raman laser using a, so-called,
broadband pump where the linewidth of pumping light is broader than the spontaneous scattering linewidth, are also discussed.
Features of both amplification and oscillation regimes of such broadband pumped Raman lasers are reported, and conditions
for the efficient frequency conversion are determined. 相似文献
5.
W. Richter H. Pascher H. G. Häfele 《Applied Physics A: Materials Science & Processing》1981,26(2):115-124
We studied the change in Spin-flip Raman (SFR) gain and behaviour of the effectiveg-value as a function of pulsed electric fields inn-type InSb. The samples were held at 1.8 K in magnetic fields up to 1.4 T. Varying the strength of a pulsed electric field applied to the samples parallel to the magnetic field we found a direct correlation between the increase in electron temperature and the decrease of the Raman gain. Measurements of the Raman gain and spontaneous line width at different times after the starting of the electric pulse and during its fall time with a time resolution of 10 ns give no indication of a motional narrowing of the SFR line and of an increase of the gain during the decrease of the electric field pulse. These two predictions were made by Mooradian et al. (1972) to explain the observed transient increase of the intensity of the stimulated SFR Stokes radiation after an electric field across the sample was switched off. With our direct measurement of the Raman gain we could establish that at any time during and after the electric field pulse, the gain is less or equal to the value without electric field. In the electric field region from 0.3 V/cm up to 0.6 V/cm the Raman gain shows several maxima, originating from SFR scattering between different spin splitted conduction band levels. The electron distribution under pulsed electric field conditions give rise to a dynamically varying absorption mechanism of transmitted radiation. Time resolved transmission measurements explain the observed increase of stimulated SFR Stokes radiation during the switch-off time of electric field pulses by a lower absorption of radiation and not by a larger gain. 相似文献
6.
M. Singh A. Sangwan S. Redhu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(3):403-410
Optical phase conjugation via stimulated Brillouin scattering (OPC-SBS) in magnetized diffusion driven semiconductors under
the off-resonant transition regime has been investigated theoretically. The model is based upon the coupled-mode approach
and
incorporates the effect of pump absorption through the first-order induced polarization. The linear dispersion is found not
to
affect the reflectivity of the phase conjugate Stokes shifted Brillouin mode. The reflectivity of the image radiation is dependent
upon the Brillouin susceptibility and can be significantly enhanced through n-type doping of the crystal and the simultaneous
application of magnetic field. Moreover, the threshold of the pump intensity required for the occurrence of SBS in the crystal
with finite optical attenuation can be considerably diminished through a suitable choice of the excess carrier concentration
and
the magnetic field. Consequently, OPC-SBS becomes a possible tool in phase-conjugate optics even under not-too-high power
laser
excitation by using moderately doped n-type semiconductors kept under the influence of magnetic field. Numerical estimates
made
for n-InSb crystal at 77 K duly irradiated by nanosecond pulsed 10.6 μm CO2 laser show that high OPC-SBS reflectivity
(70%) can be achieved at pump intensities below the optical damage threshold if the crystal is used as an optical waveguide
with
relatively large interaction length (L ∼5 mm) which proves its potential in practical applications such as fabrication of
phase
conjugate mirrors. 相似文献
7.
Coherent infrared radiation tunable between 1.6 and 3.2 μm was generated with a pulsed dye laser by 6s−5d
5/2 stimulated electronic Raman scattering in caesium vapour. We describe a technique using thermal dissociation to reduce the
density of caesium dimers in a heat-pipe oven, which produced a factor of 7 reduction in Raman threshold. The threshold displayed
a marked dependence on pump bandwidth. 相似文献
8.
Simultaneous stimulated Raman scattering at the 992 cm–1 and the 3063 cm–1 line of benzene is observed by mode-locked ruby laser pulse excitation. The double line stimulated Raman scattering is initiated by self-focusing. The influence of small-scale self-focusing, self-phase modulation, and cross-phase modulation on the double line stimulated Raman scattering is discussed. At low pump pulse intensities, before the onset of small-scale self-focusing, the steady-state Raman gain factors of both Raman lines are determined by Raman energy conversion efficiency measurements. 相似文献
9.
Li D. J. Yang G. L. Chen F. Xie J. J. Zhang L. M. Guo J. Shao C. L. Peng Z. Q. Lu Q. P. 《Laser Physics》2012,22(5):937-940
Stimulated rotational Raman scattering (SRRS) at multiwavelength pumped by TEA CO2 laser was demonstrated in this paper. Raman mediums were cooled by liquid-N2 and a multiple-pass cell (MPC) with 25 passes was designed and used. When the para-H2 was pumped by single-longitudinal-mode
(SLM) circular polarized TEA CO2 laser on 10P(20), 9P(20), and 10R(20), 50 mJ 16.95 μm, 350 mJ 14.44 μm, and 536 mJ 16.9 μm radiations were obtained, corresponding
to energy conversion efficiency of 1.2, 11.7, and 13.4%, respectively. When the ortho-D2 was pumped by CO2 laser on 10R(18), 108 mJ 12.57 μm Raman laser was obtained with energy conversion efficiency of 2.9%. 相似文献
10.
The spin-flip Raman (SFR) laser is shown to be an excellent tool to investigate different processes in the conduction band
of the SFR laser crystal itself. For the case ofn-InSb, intracavity spectroscopy of inter-Landau transitions is demonstrated to be much more sensitive than conventional transmission
spectroscopy. Data on cyclotron harmonic transitions, both free and LO-phonon assisted, are obtained from the output power
characteristics of the SFR laser versus magnetic field. The spin-splitting energy and the effectiveg-factor up to 14 T are derived from the SFR laser frequency. The influence of temperature on SFR laser power, threshold and
frequency is investigated. The relaxation following the SFR laser pulse is observed in the electrical conductivity. This yields
in a direct way the spin-lattice relaxation time at high magnetic fields, which is of the order of 200 ns. 相似文献
11.
K. A. Gonchar L. A. Golovan’ V. Yu. Timoshenko V. A. Sivakov S. Christiansen 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(12):1712-1714
The effect of light localization in photoluminescence (PL) and Raman scattering (RS) in silicon nanowires with diameter of
100 nm was investigated. The optical excitation was done by CW radiation of a YAG:Nd laser at 1.064 μm. The PL an RS intensities
were found to increase strongly for the samples with Si nanowires in comparison with corresponding values of c-Si substrate.
The effect is explained by an increase of the lifetime of photons in silicon nanowire structures. 相似文献
12.
Coherent anti-Stokes Raman scattering (CARS) and normal anti-Stokes Raman scattering (NARS) have been measured in (001) GaP at room temperature due to the 403 cm−1 LO phonons using a continuous wave (CW) 785.0 nm fixed-wavelength pump laser and a CW Stokes laser tunable in the 800-830 nm wavelength range. CARS measurements are normally made using pulsed lasers. The use of CW diode lasers allows a more accurate comparison between the measured and calculated values of the CARS signal. The pump and Stokes laser beams were linearly polarized perpendicular to each other, same as the pump and normal Stokes/anti-Stokes scattered light for the GaP sample used in this work. The pump and Stokes laser powers incident upon the GaP sample, located in the focal plane of a 20 mm effective focal length lens, were <20 and 50 mW, respectively. The diameter of the laser beams in the focal plane of the focusing lens was determined to 40±5 μm. The pump and Stokes laser beam intensities incident upon the 0.3 mm thick GaP sample were <2 and 5 kW cm2, respectively. The powers of the CARS and NARS signals were measured using a Raman spectrometer. The signal output of the Raman spectrometer was calibrated using the pump laser and several neutral density filters. The Raman linewidth (full-width at half-maximum) of the LO phonons was determined to be 0.95±0.05 cm−1, using the variation of the CARS signal with the wavelength of the Stokes laser. The measured powers of the CARS and NARS signals are about a factor of 5 and 1.5, respectively, smaller than those calculated from the corresponding theoretical expressions. 相似文献
13.
~~A Raman laser system for multi-wavelength satellite laser ranging@K.Hamal$Czech Technical University in Prague,Czech
@I.Prochazka$Czech Technical University in Prague,Czech
@J.Blazej$Czech Technical University in Prague,Czech1. Yang Fumin, Chen Wanzhen, Zhang Zhongping et al., Satellite laser ranging experiment with sub-centimeter single-shot ranging precision at Shanghai Observatory, Science in China, Ser. A, 2002, 32(10): 935-939.
2. Degnan, J. J., Millimeter accurac… 相似文献
14.
In this paper measurements of the frequency, linewidth and polarization of stimulated recombination radiation (SRR) fromp-type InSb are reported. The samples had low excess-carrier concentrations between 1014 and 1015 per cm3 and different lengths between 0.4 and 9 mm. They were held in magnetic fields up to 6T at temperatures of pumped liquid helium. The excitation was done optically by the radiation of a Q-switched CO-laser. We could observe a number of different stimulated processes:
- band-to-band recombination (tuning between 1875 and 1980 cm?1),
- band-to-acceptor recombination (tuning between 1840 and 1930 cm?1),
- stimulated spin-flip Raman scattering (SFR) of the SRR by excited electrons,
- SFR of the laser by excited electrons and its interaction with the SRR.
15.
The generation of tunable 16 μm radiation by stimulated hyper-Raman scattering from atomic strontium vapour is reported. The
infrared radiation has a linewidth of 0.4 cm−1 which corresponds to that of the nitrogen laser pumped dye laser used as a pump source. Due to relatively low pump intensity
the infrared power was only 20 mW. However, the system is easily scalable to a higher conversion efficiency. 相似文献
16.
R. Ebert H. Pascher G. Appold H. G. Häfele 《Applied Physics A: Materials Science & Processing》1977,14(2):155-159
We report for the first time stimulated magneto-Raman scattering inp-type InSb. Two different Raman scattering processes were observed. The first one has a Raman shift of about 2cm−1/kG and is observed at magnetic fields up to 30kG. The other one is observable only at high magnetic fields above 30kG and
shows Raman shifts between 1.2cm−1 and 3.0cm−1 with a tuning rate of about 0.2cm−1/kG. The first process can be interpreted either as spin-flip Raman scattering by photo-excited electrons in the conduction
band or as Raman scattering by holes in the valence band involving transitions from heavy to light hole states. The other
Raman shift observed seems to occur on account of transitions between the heavy hole ladders. 相似文献
17.
The characteristics of a coherent tunable terahertz-wave source have been experimentally investigated in detail. By using
a difference frequency generation as a result of stimulated Raman scattering by polaritons in MgO:LiNbO3 crystals, the signal wave was continuously tuned in the range of 1.069–1.075 μm, which corresponded to a terahertz-wave in
the wide range from 227 to 104 μm (1.3 to 2.9 THz). The highest output signal pulse energy at the pumping level of 44 mJ/pulse
was 1.8 mJ/pulse with 20 mW seeder injection, and the terahertz peak power was 139 mW at the wavelength of 143 μm. This source
has the advantages of simple alignment, simplicity of tuning, and compactness that makes the device more attractive. 相似文献
18.
《Applied physics. B, Lasers and optics》1981,24(1):33-38
We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with
wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation.
Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52
S
1/2−42
P
3/2,1/2 at 3.41 μm) have been identified. 相似文献
19.
Stimulated raman scattering up to 10 orders in an optical fiber 总被引:2,自引:0,他引:2
Gao Pei-juan Nie Cao-jiang Yang Tian-long Su Hai-zheng 《Applied Physics A: Materials Science & Processing》1981,24(4):303-306
This paper describes the experimental investigation of stimulated Raman scattering obtained from a multimode fiber. 10 orders
of stimulated Stokes scattering of wavelengths in the 546–702 nm region were obtained from a 480m multimode, low-loss, graded-index
quartz fiber pumped by a 532 nm frequency-doubled YAG-Nd laser beam with a pulse duration of 7 ns, output power of 0.7 MW
and repetition rates of 5 and 10 pps. 相似文献
20.
Y.-Q. Liu J. Zhang Z. Jin Z.-Q. Hao Z. Zhang Z.-H. Wang 《Applied physics. B, Lasers and optics》2008,92(2):153-157
We present the spectral dynamics investigations of supercontinuum generation from 2.6 TW femtosecond laser pulses propagation
in air. The measured spectra in the supercontinuum channel show a large amount of oscillating structure, which is mostly contributed
from four-wave mixing, stimulated Raman scattering and the electronic mechanism self-phase modulation. The temporal coherence
length is almost the same as 0.45 ps for each spectral component with the same spectral width of supercontinuum that is confirmed
with a Michelson interferometer. The spatial coherence property of supercontinuum is measured by a Young’s double slit diffractometer,
which demonstrates that supercontinuum preserves a transverse coherence of about 144 μm because of the divergence of the supercontinuum
channel.
PACS 42.62.Fi; 42.68.Ay; 43.25.Jh 相似文献