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1.
We report on the frequency doubling of Q-switchedNd:YAG and Nd:YAlO3 lasers emitting at 946 and 930 nm, respectively (4F3/2 to 4I9/2 transition). The neodymium-doped laser host crystals were excited with a flashlamp-pumped Cr:LiSAF laser operating in a free-running
mode. Blue-light pulses were obtained at both 473 nm (9 mJ, 25 ns FWHM) and 465 nm (4.4 mJ, 35 ns FWHM) by using a potassium
niobate crystal as an extra-cavity frequency doubler. The second-harmonic generation conversion efficiencies reached 53% and
31%, respectively.
Received: 23 June 1999 / Revised version: 8 August 1999 / Published online: 3 November 1999 相似文献
2.
E. György I.N. Mihailescu P. Serra A. Pérez del Pino J.L. Morenza 《Applied Physics A: Materials Science & Processing》2002,74(6):755-759
We report micrometre-sized crown-like structure growth on a Ti surface by multipulse Nd:YAG (λ=1.064 μm,τ=170 ns) laser irradiation
in air at atmospheric pressure. The irradiation was performed at 8×107 W/cm2 laser-pulse intensity, below the ablation threshold. A ring-shape structure develops in the centre of the irradiation spot
after the action of five laser pulses. The further increase of the laser-pulse number leads gradually to a crown-like structure,
which has, for 150 pulses, a height of 120–140 μm above the non-irradiated Ti surface. The forming crater’s depth does not
exceed the height of the grown structure. In the neighbouring zone, after the action of 25 laser pulses, microcracks of the
oxide surface layer develop. With the next pulses this leads to the formation of a surface microrelief. The crown-like-structure
growth is originated by molten material movement attributed to the laser-induced plasma-recoil pressure.
Received: 6 June 2001 / Accepted: 6 January 2002 / Published online: 26 March 2002 相似文献
3.
A.A. Andreev U. Teubner I.V. Kurnin E. Förster 《Applied physics. B, Lasers and optics》2000,70(4):505-515
Soft-X-radiation in the “water-window” region (23.3–43.6 ?) mainly from carbon laser plasmas generated by subpicosecond (700 fs)
0.248-μm laser pulses is studied as a function of angle of incidence and intensity (up to 1018 W/cm2) for p-polarized laser light. Furthermore, comparison is made between plasmas generated from massive and foil targets. Numerical
calculations are performed using a hydrocode coupled to X-ray line and continuum emission calculations including radiation
transport. The optimized conditions to achieve maximum water-window X-ray emissivity and, in particular, carbon Lyman-α line
emission are investigated. In addition, analytical scalings are presented. These theoretical results are essentially confirmed
by previous experiments. It is found that at optimized conditions, picosecond or subpicosecond laser plasma X-ray sources
with a power of the order of 1–10 GW in a spectral window of 1 ? could be developed.
Received: 6 August 1998 / Final version: 6 August 1999 / Published online: 30 November 1999 相似文献
4.
We have measured the absorption of the 19.47-nm neon like bromine (J=2–1) X-ray laser line in low-pressure helium. The experiment
was motivated by the coincidence of this line with the low-absorption wing of an autoionizing transition in helium. We observe
that, with 1 mbar of helium, the continuum background and another bromine X-ray laser line at 19.82 nm are strongly reduced,
enhancing the relative strength of the 19.47-nm laser line. Increasing the helium pressure to 1.5 mbar makes the continuum
virtually disappear, resulting in an almost monochromatic emission of the X-ray laser line. An estimate of the absorption
cross section for the 19.47-nm line is given as ≈3.9×10-19 cm2 and for the nearby continuum as 0.9–1.3×10-18 cm2.
Received: 8 March 1999 / Revised version: 26 April 1999 / Published online: 11 August 1999 相似文献
5.
C. Tomas J.P. Girardeau-Montaut M. Afif M. Romand M. Charbonnier T.M. Duc 《Applied Physics A: Materials Science & Processing》1997,64(5):467-471
3+ :YAG laser with 5th harmonic generator, generating 16 ps duration pulses at 213 nm, with energies up to 0.5 mJ. Experimental results concerning
the action of laser pulses, as well as the effects of residual pressure on the cleanliness of the photocathodes surface are
presented and discussed. Influence of laser pulses and residual pressure on the work function of the metal are also investigated.
Received: 15 April 1996/Accepted: 5 November
1996 相似文献
6.
A. Brockhinke W. Kreutner U. Rahmann K. Kohse-Höinghaus T.B. Settersten M.A. Linne 《Applied physics. B, Lasers and optics》1999,69(5-6):477-485
Laser-induced fluorescence of OH (A 2Σ+, v’=1) was measured in hydrogen/oxygen and hydrogen/air/nitrogen flames using laser pulses of 80 psec duration. A 2D signal
acquisition scheme simultaneously employed wavelength, temporal, and polarization resolution. The signals emitted in different
rotational branches exhibit polarization-dependent intensities, depending on the rotational branch of the absorption line
used. It is possible to select experimental conditions such that rotational and vibrational relaxation as well as electronic
quenching can be monitored simultaneously. Advantages and limitations of the experimental approach are discussed. Numerical
simulations are presented of the LIF spectra affected by energy transfer.
Received: 29 March 1999 / Revised version: 14 June 1999 / Published online: 27 October 1999 相似文献
7.
R. Schnabel M. Schultz-Johanning M. Kock 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):267-269
Radiative lifetimes of 19 selected W II levels with energies between 36 000 cm-1 and 55 000 cm-1 have been measured with the time-resolved laser-induced fluorescence technique. The ions are generated in a hollow cathode
discharge and stored in a linear Paul trap. Selected states are populated with tunable dye laser pulses and the subsequent
fluorescence is measured by means of a 5 Gigasample transient digitizer and a fast photodetector with a risetime of 700 ps.
By taking into account both the temporal profile of the laser pulses and the separately measured response function of the
system, the lifetime can be determined from the full decay curve. A refined evaluation procedure, taking into account saturation
effects in the signals, reduces the uncertainty in our data to around 1%.
Received: 30 July 1998 / Revised: 18 August 1998 相似文献
8.
4-W and 23-ps pulses from a lamp-pumped Nd:YAG laser passively mode-locked by polarization switching in a KTP crystal 总被引:1,自引:0,他引:1
V. Kubeček V. Couderc B. Bourliaguet F. Louradour A. Barthélémy 《Applied physics. B, Lasers and optics》1999,69(2):99-102
Passive mode-locking of a cw lamp-pumped Nd:YAG laser using nonlinear polarization switching in a type-II SHG crystal is reported.
Light pulses with more than 5 W of average power and pulse duration shorter than 25 ps have been obtained at 1064 nm.
Received: 29 January 1999 / Revised version: 24 March 1999 / Published online: 1 July 1999 相似文献
9.
A laser-based method for measuring the three components of the velocity in a plane simultaneously and instantaneously without
seed particles is presented. This is achieved by combining a laser flow-tagging technique with stereoscopic detection, in
which the tagged flow is viewed from two different directions. A single CCD camera is employed for this purpose by using a
new optical detection system. The flow tagging is performed by two consecutive laser pulses, i.e., “write” and “read” laser
pulses. The write laser creates a grid of tracer molecules (NO) by inducing a photodissociation process. The three-dimensional
motion of the tracer molecules is measured by a thick read laser sheet.
Received: 22 July 1999 / Revised version: 5 August 1999 / Published online: 30 September 1999 相似文献
10.
The small-signal gain coefficient and the saturation intensity of a F2 pulsed discharge molecular laser at 157 nm have been measured using two discharge devices in an oscillator-amplifier configuration. The small signal gain coefficient was measured to be 5.2±0.4% cm–1 at 3 atm total pressure and 1.5 cm electrode spacing and 4.1±0.4% cm–1 at 2 atm total pressure and 2 cm electrode spacing while the values of the saturation intensity were 5 MW/cm2 and 4.6 MW/cm2, respectively. 相似文献
11.
Production and characterization of Nd,Cr:GSGG thin films on Si(001) grown by pulsed laser ablation 总被引:2,自引:0,他引:2
P.R. Willmott P. Manoravi K. Holliday 《Applied Physics A: Materials Science & Processing》2000,70(4):425-429
Nd,Cr:Gd3Sc2Ga3O12 (GSGG) thin films have been produced for the first time. They were grown on Si(001) substrates at 650 °C by pulsed laser
ablation at 248 nm of a crystalline Nd,Cr:GSGG target rod. The laser plume was analyzed using time-of-flight quadrupole mass
spectroscopy, and consisted of elemental and metal oxide fragments with kinetic energies typically in the range 10 to 40 eV,
though extending up to 100 eV. Although films deposited in vacuum using laser fluences of 0.8±0.1 J cm−2 reproduced the Nd,Cr:GSGG bulk stoichiometry, those deposited using fluences above ≈3 J cm−2 resulted in noncongruent material transfer and were deficient in Ga and Cr. Attempts to grow films using synchronized oxygen
or oxygen/argon pulses yielded mixed oxide phases. Under optimal growth conditions, the films were heteroepitaxial, with GSGG(001)[100]∥Si(001)[100],
and exhibited Volmer–Weber-type growth. Room-temperature emission spectra of the films suggest efficient non-radiative energy
transfer between Cr3+ and Nd3+ ions, similar to that of the bulk crystal.
Received: 1 October 1999 / Accepted: 15 October 1999 / Published online: 23 February 2000 相似文献
12.
G. Cristoforetti S. Legnaioli V. Palleschi A. Salvetti E. Tognoni 《Applied physics. B, Lasers and optics》2005,80(4-5):559-568
A collinear double pulse laser-induced plasma was characterised by means of a spectrally and time resolved imaging technique. The beams of two Q-switched Nd:YAG lasers were focused on a brass target in a vacuum chamber to form the plasma. The plume emission intensity and spatial distribution were recorded with temporal resolution using an intensified CCD. Using a set of interference filters, we collected images of the emission from the major target components as well as from oxygen. Both the laser inter-pulse separation (in the range between 0 and 10 s) and the ambient air pressure value (in the range between 105 and 10 Pa) were varied during the experiment. At atmospheric pressure, an enhancement of the line emission from the target elements was observed for delayed laser pulses compared to coincident pulses. However, this enhancement effect tends to fall at low pressure values, and a decrease of the signal is observed for pressures under about 104 Pa. Moreover, it was observed that the evaluation of the enhancement factor strongly depends on the detector field of view. The propagation of the emitting plume was also studied at several pressures and inter-pulse delays. 相似文献
13.
M. Grozeva M. Kocik J. Mentel J. Mizeraczyk T. Petrov P. Telbizov D. Teuner N. Sabotinov J. Schulze 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):277-286
Our investigations demonstrated that utilizing copper bromide (CuBr) mixture as a source of Cu atoms in a RF-excited discharge
can be a promising alternative to the Cu sputtered system, when the development of Cu ion gas laser is considered. Both spectroscopic
and laser investigations showed that the threshold input power for lasing was reduced about 5 times using the CuBr-based system
instead of the Cu-sputtered system. Pulsed and CW laser oscillation on Cu+ transitions in the near IR spectral region was obtained in RF-excited He-CuBr discharge operated at 13.56 MHz and 27.12 MHz.
At input RF power of 800 W, a laser output power of 10 mW at the 780.8 nm Cu ion laser line was achieved. An increase of laser
output power by a factor of two, as well as better Cu vapour axial distribution and better discharge stability, was attained
when DC discharge was superimposed on the RF discharge. Laser gain on 11 UV Cu ion lines was observed in RF-excited Ne-CuBr
discharge. basing on the obtained results, we consider the CuBr laser system excited by RF discharge capable of generating
UV laser radiation at relatively low input power.
Received 4 January 1999 相似文献
14.
S.K. Lam D. Lo C.E. Zheng C.L. Yuan C. Shangguan T.L. Yang I.V. Kochetov 《Applied physics. B, Lasers and optics》2002,75(6-7):723-730
Optical and electrical properties of a high-pressure discharge of pure xenon and xenon-helium and xenon-neon mixtures are
studied experimentally. Uniform discharge at total gas pressure as high as 10 atm is achieved in xenon-lean mixtures. Vacuum
ultraviolet emissions due to the first and second continua of Xe2
* are examined spectroscopically. The vibrational relaxation rate constant kHe of Xe2
* by helium is determined to be of the order of 10-11 cm3 s-1 from spectroscopic data. Laser oscillation for the 172-nm band was attempted without success. Discharge instability at high
gas pressures is considered to the cause of the unsuccessful laser experiments. Some issues related to discharge instability
in a high-pressure rare-gas discharge are discussed.
Received: 1 October 2001 / Revised version: 11 June 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +852-2603/5204, E-mail: dlo@phy.mhk.edu.hk 相似文献
15.
M.E. Garcia H.O. Jeschke I. Grigorenko K.H. Bennemann 《Applied physics. B, Lasers and optics》2000,71(3):361-371
We present a theoretical study of the short-time relaxation of clusters in response to ultrafast excitations using femtosecond
laser pulses. We analyze the excitation of different types of clusters (Hgn, Agn, Sin, C60 and Xen) and classify the relaxation dynamics in three different regimes, depending on the intensity of the exciting laser pulse.
For low-intensity pulses (I<1012 W/cm2) we determine the time-dependent structural changes of clusters upon ultrashort ionization and photodetachment. We also study
the laser-induced non-equilibrium fragmentation and melting of Sin and C60 clusters, which occurs for moderate laser intensities, as a function of the pulse duration and energy.
As an example for the case of high intensities (I>1015 W/cm2), the explosion of clusters under the action of very intense ultrashort laser fields is described.
Received: 26 November 1999 / Published online: 2 August 2000 相似文献
16.
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
17.
E. D'Anna S. Luby A. Luches E. Majkova M. Martino 《Applied Physics A: Materials Science & Processing》1993,56(5):429-436
Interdiffusion phenomena, thermal damage and ablation of W/Si and Si/W bilayers and multilayers under XeCl-excimer laser (=308 nm) irradiation at fluences of 0.15, 0.3 and 0.6 J/cm2 were studied. Samples were prepared by UHV e-beam evaporation onto oxidized Si. The thickness of W and Si layers and the total thickness of the structures were 1–20 nm and 40–100 nm, respectively. 1 to 300 laser pulses were directed to the same irradiation site. At 0.6 J/cm2 the samples were damaged even by a single laser pulse. At 0.3 J/cm2 WSi2 silicide formation, surface roughening and ablation were observed. The threshold for significant changes depends on the number of pulses: it was between 3–10 pulses and 10–30 pulses for bilayers with W and Si surfaces, respectively, and more than 100 pulses for multilayers with the same total thickness of tungsten. At 0.15 J/cm2 the periodicity of the multilayers was preserved. Temperature profiles in layered structures were obtained by numerical simulations. The observed differences of the resistance of various bilayers and multilayers against UV irradiation are discussed. 相似文献
18.
Modification of the fused silica glass network associated with waveguide fabrication using femtosecond laser pulses 总被引:1,自引:0,他引:1
J.W. Chan T.R. Huser S.H. Risbud D.M. Krol 《Applied Physics A: Materials Science & Processing》2003,76(3):367-372
Atomic-scale structural changes have been observed in the glass network of fused silica after modification by tightly focused
800-nm, 130-fs laser pulses at fluences between 5 and 200 J cm-2. Raman spectroscopy of the modified glass shows an increase in the 490 and 605-cm-1 peaks, indicating an increase in the number of 4- and 3-membered ring structures in the silica network. These results provide
evidence that densification of the glass occurs after exposure to fs pulses. Fluorescence spectroscopy of the modified glass
shows a broad fluorescence band at 630 nm, indicating the formation of non-bridging oxygen hole centers (NBOHC) by fs pulses.
Waveguides that support the fundamental mode at 633 nm have been fabricated inside fused silica by scanning the glass along
the fs laser beam axis. The index changes are estimated to be approximately 0.07×10-3.
Received: 17 December 2001 / Accepted: 9 July 2002 / Published online: 25 October 2002
RID="*"
ID="*"Corresponding author. Fax: +1-925/423-2463, E-mail: dmkrol@ucdavis.edu 相似文献
19.
Permanent holographic recording in indium oxide thin films using 193 nm excimer laser radiation 总被引:2,自引:0,他引:2
S. Pissadakis S. Mailis L. Reekie J.S. Wilkinson R.W. Eason N.A. Vainos K. Moschovis G. Kiriakidis 《Applied Physics A: Materials Science & Processing》1999,69(3):333-336
Permanent holographic recording in sputtered indium oxide (InOx) thin films is demonstrated, using ultraviolet radiation at 193 nm emitted by an ArF excimer laser. Steady-state refractive
index changes of up to 5×10-3 are calculated from the measured diffraction efficiency of a HeNe laser probe beam. The recorded gratings exhibit a dynamic
behaviour that relaxes to a steady-state value that depends on the oxygen partial pressure used during growth and on the recording
beam intensity. The observed behaviour is explained in terms of laser-induced structural changes.
Received: 12 October 1998 / Accepted: 8 March 1999 / Published online: 4 August 1999 相似文献
20.
J. P. Fischer J. Dams M. H. Götz E. Kerker F. H. Loesel C. J. Messer M. H. Niemz N. Suhm J. F. Bille 《Applied physics. B, Lasers and optics》1994,58(6):493-499
Plasma-mediated ablations of brain tissue have been performed using picosecond laser pulses obtained from a Nd:YLF oscillator/regenerative amplifier system. The laser pulses had a pulse duration of 35 ps at a wavelength of 1.053 µm. The pulse energy varied from 90 µJ to 550 µJ at a repetition rate of 400 Hz. The energy density at the ablation threshold was measured to be 20 J/cm2. Comparisons have been made to 19 ps laser pulses at 1.68 µm and 2.92 µm from an OPG/OPA system and to microsecond pulse trains at 2.94 µm from a free running Er:YAG laser. Light microscopy and scanning electron microscopy were performed to judge the depth and the quality of the ablated cavities. No thermal damage was induced by either of the picosecond laser systems. The Er:YAG laser, on the other hand, showed 20 µm wide lateral damage zones due to the longer pulse durations and the higher pulse energies. 相似文献