共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Jackson E.M. Telles M.D. Allen K.M. Evenson 《Applied physics. B, Lasers and optics》2001,72(7):815-818
A significantly improved far-infrared laser has been used to generate optically pumped laser emissions from 26 to 150 μm for
CD3OH. Using an X–V-pumping geometry, several new laser emissions have been found for CD3OH. In addition, an increase in power, by factors from 10 to 1000, for many of the previously known shorter-wavelength laser
lines, below 100 μm, has been observed. Frequency measurements for several lines have also been performed and have been reported
to a fractional uncertainty up to ±2×10-7, permitting the spectroscopic assignment of the laser transition. One of the frequency-measured lines, 44.256 μm observed
using the 10R34 pump, has confirmed the assignment of the previously reported FIR emission (n,K;J)=(1,7;20)?(0,8;20)A in the
ground vibrational state.
Received: 26 October 2000 / Published online: 7 February 2001 相似文献
2.
M.?Silies H.?Witte S.?Linden J.?Kutzner I.?Uschmann E.?F?rster H.?Zacharias 《Applied Physics A: Materials Science & Processing》2009,96(1):59-67
The interaction of ultrashort laser pulses with solid state targets is studied concerning the production of short X-ray pulses
with photon energies up to about 10 keV. The influence of various parameters such as pulse energy, repetition rate of the
laser system, focusing conditions, the application of prepulses, and the chirp of the laser pulses on the efficiency of this
highly nonlinear process is examined. In order to increase the X-ray flux, the laser pulse energy is increased by a 2nd multipass
amplifier from 750 μJ to 5 mJ. By applying up to 4 mJ of the pulse energy a X-ray flux of 4×1010 Fe K
α
photons/s or 2.75×1010 Cu K
α
photons/s are generated. The energy conversion efficiency is therefore calculated to η
Fe≈1.4×10−5 and η
Cu≈1.0×10−5. The X-ray source size is determined to 15×25 μm2. By focusing the produced X-rays using a toroidally bent crystal a quasi-monochromatic X-ray point source with a diameter
of 56 μm×70μm is produced containing ≈104 Fe K
α1 photons/s which permits the investigation of lattice dynamics on a picosecond or even sub-picosecond time scale. The lattice
movement of a GaAs(111) crystal is shown as a typical application. 相似文献
3.
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
4.
The spatial characteristic of an aluminum laser-induced plasma are studied at a laser radiation intensity of (3.8–4.8) × 108 W/cm2 and an air residual pressure of 6.7–133.3 Pa. It is found that the duration of the aluminum plasma glow is 50 μs and decreases
with decreasing laser power output. The glow intensity reaches a maximum at t = 1.4 μs and rises with laser energy. Typical sizes of the emitting area on the laser torch are determined. 相似文献
5.
S.A. Starostin I.V. Kochetov P.J.M. Peters Y.B. Udalov W.J. Witteman A.P. Napartovich 《Applied physics. B, Lasers and optics》2000,71(4):491-494
The performance of a RF excited cw atomic xenon laser at wavelengths of 2.03 μm and 2.65 μm was studied theoretically and
experimentally as a function of electrode distance. Results for inter-electrode distances from 2 to 0.25 mm are presented.
A high pumping rate resulted in strong 40 mW cw amplified spontaneous emission at 2.65 μm wavelength from the configuration
with the smallest distance of 0.25 mm between the electrodes. The maximum laser output of 2.7 W (0.24 W/cm3) was obtained with an active medium volume of 2×15×370 mm3 whereas the maximum specific output of 1.9 W/cm3 was received for an active medium volume of 0.25×2.25×370 mm3. A fluid model of the RF discharge was developed to analyze the laser behavior for different distances between the electrodes.
Received: 30 November 1999 / Revised version: 21 April 2000 / Published online: 6 September 2000 相似文献
6.
Dattatray J. Late Vindhyesh R. Singh Sucharita Sinha Mahendra A. More K. Dasgupta Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2009,97(4):905-909
Micro/nano structures have been obtained by laser surface treatment on sintered LaB6 pellets employing a picosecond pulsed Nd:YAG laser at a pressure of ∼1×10−3 mbar. The X-ray diffraction pattern of the laser treated pellet shows a set of well defined diffraction peaks, indexed to
the cubic phase of LaB6 only. The scanning electron microscope studies reveal formation of micro and nano structures upon laser treatment and the
resultant surface morphology is found to be strongly influenced by the laser fluence. Field electron emission studies made
on the LaB6 pellet, treated with optimized laser fluence, have been performed in a planar diode configuration under ultra high vacuum
conditions. The threshold field required to draw an emission current density of ∼10 μA/cm2 has been found to be ∼2.3 V/μm and a current density of ∼530 μA/cm2 has been drawn at an applied field of 5.2 V/μm. The Fowler-Nordheim plot is found to be linear in accordance with the quantum
mechanical tunneling phenomenon, confirming the metallic nature of the emitter. The emission current at the pre-set value
∼10 μA shows very good stability over a period of more than 3 hours. The present results emphasize the effectiveness of a
picosecond laser treatment towards fabrication of a nano metric LaB6 emitter for high current density applications. 相似文献
7.
Stabilization method of an infrared two-wavelength laser 总被引:1,自引:0,他引:1
H. Matsumoto 《Applied physics. B, Lasers and optics》1981,24(1):65-66
A simple method for stabilizing a He-Xe laser, which simultaneously operates at two wavelengths of 3.51 μm and 3.37 μm, is
described. This stabilization method depends on the comparison of the light intensities of the two wavelengths, and has a
possibility of realizing a stability of better than 1×10−8 with unmodulated output. 相似文献
8.
Dattatray J. Late Ranjit V. Kashid Chandra Sekhar?Rout Mahendra A. More Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2010,98(4):751-756
Field emission studies of WO2.72 nanowires synthesized by a solvothermal method have been performed in the planar diode configuration under ultra high vacuum
conditions. Fowler–Nordheim plots obtained from the current-voltage characteristics follow the quantum mechanical tunneling
process and a current density of ∼8.3×106 μA/cm2 can be drawn at an applied electric field of 2 V/μm. The field enhancement factor is 33025, while the turn-on field is only
1.4 V/μm. The emission current-time plot recorded at the pre-set value of emission current of 1 μA over a period of more than
3 h exhibits an initial increase and a subsequent stabilization of the emission current. The results reveal that the WO2.72 nanowire emitters synthesized by the solvothermal method are promising cathode materials for practical applications. 相似文献
9.
We present the first photoacoustic spectrometer for gas sensing employing both the fundamental and the frequency-doubled radiation
of a continuously tunable high-pressure CO2 laser with room temperature operation. A quasi-phase-matched diffusion-bonded GaAs crystal is used in the system for second-harmonic
generation. A pulsed photoacoustic detection scheme with a non-resonant cell, equipped with an 80-microphone array, is employed.
The wide continuous tuning range in the fundamental (9.2–10.7 μm) and the frequency-doubled (4.6–5.35 μm) regimes, together
with the narrow linewidth of 540 MHz (0.018 cm-1) for the 10-μm region and of 1050 MHz (0.0315 cm-1) for the 5-μm region, allow the measurement of gas mixtures, individual species and isotope discrimination. This is illustrated
with measurements on NO and CO2. The measured isotope ratio 15
NO/14
NO=(3.58±0.55)×10-3 agrees well with the literature (3.700×10-3) and demonstrates the good selectivity of the system.
Received: 30 April 2002 / Revised version: 10 June 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +41-1/633-1077, E-mail: sigrist@iqe.phys.ethz.ch 相似文献
10.
Optical rectification in single crystals of tellurium produced by infra-red radiation at 10.6 μm has been observed. The value
of |χ0
111| is found to be 0.9×10−6 esu. Preliminary experiments to test the usefulness of the effect to monitor mode-locked infra-red laser pulses have been
inconclusive. 相似文献
11.
X. Lu Q. Yang C. Xiao A. Hirose 《Applied Physics A: Materials Science & Processing》2006,82(2):293-296
Diamond nanocone, graphitic nanocone, and mixed diamond and graphitic nanocone films have been synthesized through plasma
enhanced hot filament chemical vapor deposition (HFCVD). The field emission properties of these films have been experimentally
investigated. The studies have revealed that all three kinds of nanocone films have excellent field electron emission (FEE)
properties including low turn-on electric field and large emission current at low electric field. Compared with the diamond
nanocone films (emission current of 86 μA at 26 V/μm with the turn-on field of 10 V/μm), the graphitic nanocone films exhibit
higher FEE current of 1.8×102 μA at 13 V/μm and a lower turn-on filed of 4 V/μm. The mixed diamond and graphitic nanocone films have been found to posses
FEE properties similar to graphitic nanocone films (emission current of 1.7×102 μA at 20 V/μm with the turn-on field of 5 V/μm), but have much better FEE stability than the graphitic nanocone films.
PACS 81.07.Bc; 81.05.Uw; 79.70.+q 相似文献
12.
The crystal of Nd3+:Sr6YSc(BO3)6 with dimensions of O 19×42 mm3 was grown by the Czochralski method. It’s spectral and laser properties have been investigated. The absorption cross section
is 1.47×10-20 cm2 with a FWHM 12.0 nm at 807 nm, the emission cross section is 1.57×10-19 cm2 at 1060 nm, and the fluorescence lifetime is 76 μs at room temperature. The maximum laser output is 25.7 mJ at 1.06 μm pumped
by a single Xenon flash lamp and the overall and average slope efficiencies are 0.12% and 0.09%, respectively. The laser energy
threshold value is 1.28 J.
PACS 42.55.Rz; 42.70.Hj; 78.20.-e 相似文献
13.
G. Franzò V. Vinciguerra F. Priolo 《Applied Physics A: Materials Science & Processing》1999,69(1):3-12
A detailed investigation on the excitation mechanisms of rare-earth (RE) ions introduced in Si nanocrystals (nc) is reported.
Silicon nanocrystals were produced by high-dose 80-keV Si implantation in thermally grown SiO2 followed by 1100 °C annealing for 1 h. Subsequently some of the samples were implanted by 300-keV Er, Yb, Nd, or Tm at doses
in the range 2×1012–3×1015 /cm2. The energy was chosen in such a way to locate the RE ions at the same depth where nanocrystals are. Finally an annealing
at 900 °C for 5 min was performed in order to eliminate the implantation damage. These samples show intense room-temperature
luminescence due to internal 4f shell transitions within the RE ions. For instance, luminescence at 1.54 μm and 0.98 μm is
observed in Er-doped nc, at 0.98 μm in Yb-doped nc, at 0.92 μm in nc and two lines at 0.78 μm and 1.65 μm in Tm-doped nc.
Furthermore, these signals are much more intense than those observed when RE ions are introduced in pure SiO2 in the absence of nanocrystals, demonstrating the important role of nanocrystals in efficiently exciting the REs. It is shown
that the intense nc-related luminescence at around 0.85 μm decreases with increasing RE concentration and the energy is preferentially
transferred from excitons in the nc to the RE ions which, subsequently, emit radiatively. The exact mechanism of energy transfer
has been studied in detail by excitation spectroscopy measurements and time-resolved photoluminescence. On the basis of the
obtained results a plausible phenomenological model for the energy transfer mechanism emerges. The pumping laser generates
excitons within the Si nanocrystals. Excitons confined in the nc can either give their energy to an intrinsic luminescent
center emitting at around 0.85 μm nor pass this energy to the RE 4f shell, thus exciting the ion. The shape of the luminescence
spectra suggests that excited rare-earth ions are not incorporated within the nanocrystals and the energy is transferred at
a distance while they are embedded within SiO2. Rare-earth excitation can quantitatively be described by an effective cross section σeff taking into account all the intermediate steps leading to excitation. We have directly measured σeff for Er in Si nc obtaining a value of ≈2×10−17 cm2. This value is much higher than the cross section for excitation through direct photon absorption (8×10−21 cm2) demonstrating that this process is extremely efficient. Furthermore, the non-radiative decay processes typically limiting
rare-earth luminescence in Si (namely back-transfer and Auger) are demonstrated to be absent in Si nc further improving the
overall efficiency of the process. These data are reported and their implications.
Received: 9 April 1999 / Accepted: 10 April 1999 / Published online: 2 June 1999 相似文献
14.
Placing one 0.1 mm YAG F-P etalon at nearly Brewster angle and combined use 1 mm fused silica in the cavity, a diode-pumped
linear-polarized single-longitudinal-mode (SLM) Tm:YAG laser operating at 2 μm is achieved. This paper is focused on the stability
of the linear-polarized SLM laser, including power stability, long-term frequency stability and short-term frequency stability.
And the factors affecting the frequency characteristics of laser were also analyzed. The instability of the linear-polarization
SLM laser is less than 1%. The long-term frequency stability is in the range from 1.16 × 10−7 to 1.75 × 10−7 monitored by the wave meter. And the short-term frequency stability is 97 Hz/μs measured with the self-beating heterodyne
detection method. 相似文献
15.
W. Wang P.X. Wang Y.K. Ho Q. Kong Y. Gu S.J. Wang 《Applied physics. B, Lasers and optics》2007,88(2):273-279
Using three-dimensional test particle simulations, we investigated electrons accelerated by a focused flat-top laser beam
at different intensities and flatness levels of the beam profile before focusing in vacuum. The results show that the presence
of sidelobes around the main focal spot of the focused flat-top laser beam influences the optimum (as far as electron acceleration
is concerned) initial momentum (and incident angle) of electrons for acceleration. The difference of initial conditions between
laser beams with and without sidelobes becomes evident when the laser field is strong enough (a0>10, corresponding to intensities I>1×1020 W/cm2 for the laser wavelength λ=1 μm, where a0 is a dimensionless parameter measuring laser intensity). The difference becomes more pronounced at increasing a0. Because of the presence of sidelobes, there exist three typical CAS (capture and acceleration scenario) channels when a0≥30 (corresponding to I>1×1021 W/cm2 for λ=1 μm). The energy spread of the outgoing electrons is also discussed in detail.
PACS 41.75.Jv; 42.60.Jf; 42.25.Fx 相似文献
16.
We fabricate a transparent glass ceramic contains magnesium-aluminum spinel nanocrystallites doped with Co2+ ions. The ground-state and excited-state absorption cross section of this glass ceramic at 1.54 μm are estimated to be (2.8
± 0.3) × 10−19 cm2 and (4.8 ± 0.5) × 10−20 cm2, respectively. For the first time, the passively Q-swithched operation of LD pumped 1.54 μm microchip Yb3+/Er3+ glass laser is realized with transparent glass ceramic as saturable absorber. The Q-switched pulses of 3.846 kHz in repetition
rate, 6.2 ns in duration and 6.3 μJ in energy are obtained. At last, the dependences of pulse width and repetition rate on
pump power are also investigated. 相似文献
17.
4 I13/2 and 4I11/2 of erbium is measured in a fluorozirconate fiber in the wavelength range 780–840 nm. Using a pump- and probe-beam technique
and choosing the pump wavelength such that the perturbation by pump ESA is minimized in the measurement, it is possible to
determine the effective ESA cross sections, despite the fact that the excitation is distributed among two metastable levels.
The derived ESA cross sections at 793 nm of 1.4×10-21 cm2 from the 4I13/2 level and less than 0.1×10-21 cm2 from the 4I11/2 level are in reasonable agreement with former results obtained from a rate-equation simulation of the erbium 3-μm laser.
The corresponding ESA spectrum under 3-μm lasing conditions is derived. At the strongest ground-state absorption around 799 nm,
decreasing ESA from the 4I13/2 level is compensated by increasing ESA from the 4I11/2 level, i.e., ESA losses cannot be avoided when pumping around 800 nm. This result is of relevance for possible high-power
diode pumping of an erbium 3-μm double-clad fiber laser.
Received: 20 January 1998 相似文献
18.
S.?Sujecki L.?Sójka E.?Bere?-Pawlik Z.?Tang D.?Furniss A.?B.?Seddon T.?M.?Benson 《Optical and Quantum Electronics》2010,42(2):69-79
A simple Dy3+-doped chalcogenide glass fibre laser design for mid-infrared light generation is studied using a one dimensional rate equation
model. The fibre laser design employs the concept of cascade lasing. The results obtained demonstrate that efficient cascade
lasing may be achieved in practice without the need for fibre grating fabrication, as a sufficient level of feedback for laser
action is provided by Fresnel light reflection at chalcogenide glass fibre–air interfaces. Further enhancement of the laser
efficiency can be achieved by terminating one of the fibre ends with a mirror. A numerical analysis of the effect of the Dy3+ doping concentration and fibre loss on the laser operation shows that with 5 W of pump power, at 1.71 μm wavelength, output
powers above 100 mW at ∼ 4.5 μm wavelength can be achieved with Dy3+ ion concentrations as low as 3 × 1019 cm−3, when fibre loss is of the order 1dB/m. 相似文献
19.
Mohammod Aminuzzaman Akira Watanabe Tokuji Miyashita 《Journal of nanoparticle research》2010,12(3):931-938
This article describes fabrication of Ag micropatterns on a flexible polyimide (PI) film by laser direct writing using an
Ag nanoparticle-dispersed film as a precursor. Ag micropatterns are characterized by optical microscopy, atomic force microscopy
(AFM), field emission scanning electron microscopy (FE-SEM), surface profilometry, and resistivity measurements. The line
width of Ag micropatterns can be effectively controlled by altering the experimental parameters of laser direct writing especially
laser intensity, objective lens, and laser beam scanning speed etc. Using an objective lens of 100× and laser intensity of
170.50 kW/cm2, Ag micropatterns with a line width of about 6 μm have been achieved. The Ag micropatterns show strong adhesion to polyimide
surface as evaluated by Scotch-tape test. The resistivity of the Ag micropatterns is determined to be 4.1 × 10−6 Ω cm using two-point probe method. This value is comparable with the resistivity of bulk Ag (1.6 × 10−6 Ω cm). 相似文献
20.
K. R. Allakhverdiev M. Ö. Yetis T. K. Baykara S. M. T. Özbek E. Yu. Salaev 《Laser Physics》2011,21(3):598-600
Two methods of preparation of the devices for visualization of pulsed and continuous near-IR (near infrared) are described
and the results of conversion of pulsed and continuous IR (800–1360 nm) laser radiation into the visible range of spectra
(400–680 nm) by using a transparent substrate covered with the particles (including nanoparticles) of effective nonlinear
materials of GaSe
x
S1 − x
(0.2 ≤ x ≤ 0.8) are presented. Converted light can be detected in transmission or reflection geometry as a visible spot corresponding
to the real size of the incident laser beam. Developed device structures can be used for checking if the laser is working
or not, for optical adjustment, for visualization of distribution of laser radiation over the cross of the beam and for investigation
of the content of the laser radiation. Low energy (power density) limit for visualization of the IR laser pulses with 2–3
ps duration for these device structures are: between 4.6–2.1 μJ (3 × 10−4−1 × 10−4 W/cm2) at 1200 nm; between 8.4–2.6 μJ (4.7 × 10−4−1.5 × 10−4 W/cm2) at 1300 nm; between 14.4–8.1 μJ (8.2 × 10−4–4.6 × 10−4 W/cm2) at 1360 nm. Threshold damage density is more than 10 MW/cm2 at λ = 1060 nm, pulse duration τ = 35 ps. The results are compared with commercially existing laser light visualizators. 相似文献