共查询到20条相似文献,搜索用时 453 毫秒
1.
T. Yabe C. Phipps K. Aoki M. Yamaguchi R. Nakagawa C. Baasandash Y. Ogata M. Shiho G. Inoue M. Onda K. Horioka I. Kajiwara K. Yoshida 《Applied Physics A: Materials Science & Processing》2003,77(2):243-249
Laser-supported propulsion of a micro-airplane with a water-covered ablator is demonstrated. The repetitive use of an overlay
structure is experimentally demonstrated with a specially designed water supply. Various transparent overlays are investigated
by the CIP-based hydrodynamic code and by experiments using a pendulum and using a semi-conductor load cell. A momentum-coupling
efficiency of ∼104 N s/MJ is achieved by water–exotic-target experiments, in agreement with the simulation code, which predicts a maximum efficiency
of ∼105 N s/MJ. The concept of laser-supported propulsion can also be used for driving a Mach 5 airplane in the stratosphere, a micro-ship
inside the human body, and a robot in a nuclear power reactor accident, during which large numbers of neutrons make electronic
devices useless.
Received: 7 October 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +81-3/5734-2165, E-mail: yabe@mech.titech.ac.jp 相似文献
2.
J.C. Bermudez Gutierrez M.J. Damzen V.J. Pinto-Robledo A.V. Kir’yanov J.J. Soto-Bernal 《Applied physics. B, Lasers and optics》2003,76(1):13-16
The analysis of compact CW diode-side-pumped grazing-incidence-geometry Nd:YVO4 laser designs is presented. An output power of 5 W (λ=1064 nm) was produced at 17 W of diode pump (conversion efficiency
of 30%) in single transverse TEM00 mode operation at high laser beam quality (Mx
2≈1.05 and My
2≈1.01). The resonator geometry was analyzed by applying generalized 4×4 matrix modeling of the spatial mode size, including
the impact on the laser operation of cavity astigmatism and a thermal lens in the laser slab. The simplicity and compactness
of the laser cavities allow their use for technological applications.
Received: 31 July 2002 / Published online: 22 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: m.damzen@ic.ac.uk 相似文献
3.
A. Fix M. Wirth A. Meister G. Ehret M. Pesch D. Weidauer 《Applied physics. B, Lasers and optics》2002,75(2-3):153-163
A pulsed optical parametric oscillator (OPO) with intracavity sum frequency mixing was developed generating energies of up
to 16 mJ in the 281–293 nm wavelength range. Both OPO process and sum frequency mixing are pumped by the harmonics of a single,
medium-sized Nd:YAG laser. The system is characterized by a high overall efficiency (∼4% conversion from 1064 nm to the UV),
a very compact set-up and stable and reliable operation. This system was successfully employed to measure tropospheric ozone
using the differential absorption lidar (DIAL) technique and shows much promise as a lidar transmitter in airborne case studies
as well as in unattended lidar systems for long-term monitoring. An unattended ozone profiling system could already be successfully
realized.
Received: 1 April 2002 / Revised version: 30 May 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-8153/28-1271, E-mail: Andreas.Fix@dlr.de 相似文献
4.
We report on germania/organically modified silane (ormosil) hybrid materials produced by the sol–gel technique for photonic
applications. Acid-catalyzed solutions of γ-glycidoxypropyltrimethoxysilane mixed with germanium isopropoxide have been used
as precursors for the hybrid materials. Planar waveguide films with a thickness of about 2 μm have been prepared by a single
spin-coating process and low-temperature heat treatment from these high germanium content hybrid materials. Atomic force microscopy,
thermal gravimetric analysis, UV–visible spectroscopy, and Fourier-transform infrared spectroscopy have been used to investigate
the optical and structural properties of the films. The results have indicated that a dense, low absorption, and high transparency
(in the visible range) waveguide film could be achieved at a low temperature. A strong UV-absorption region at short wavelengths
∼200 nm, accompanied by a shoulder peaked at ∼240 nm, has been noticed due to the neutral oxygen monovacancy defects. The
propagation mode and loss properties of the planar waveguide films have also been investigated by using a prism-coupling technique.
Received: 5 November 2002 /
Revised version: 27 December 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +65-67909081, E-mail: ewxque@ntu.edu.sg 相似文献
5.
J. Kodymová O. Špalek V. Jirásek M. Čenský G.D. Hager 《Applied Physics A: Materials Science & Processing》2003,77(2):331-336
This article addresses the development of a Chemical Oxygen-Iodine Laser (COIL) with alternative chemical ways of generating
atomic iodine. Injection of atomic iodine as opposed to molecular iodine has the potential to improve the COIL efficiency.
This paper describes two chemical methods for generating iodine atoms based on the gas phase reactions of hydrogen/deuterium
iodide with fluorine or chlorine atoms, which are also produced chemically. Simplified one-dimensional gas dynamic modeling
that describes the stream-wise profiles of species concentrations within both reaction systems is used to gain a theoretical
understanding of both reaction systems under COIL conditions. The modeling results are used for the design of an experimental
device and the interpretation of experimental data. The first experimental investigation studies the production of iodine
atoms produced from reactions of Cl with HI. Atomic iodine yields of 70–100% in nitrogen are obtained, and the gain on the
I(2
P
1/2)–I(2
P
3/2) transition in a flow of singlet oxygen is measured.
Received: 7 October 2002 / Accepted: 8 February 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +420-2/8689-0527, E-mail: kodym@fzu.cz 相似文献
6.
V.S. Yakovlev P. Dombi G. Tempea C. Lemell J. Burgdörfer T. Udem A. Apolonski 《Applied physics. B, Lasers and optics》2003,76(3):329-332
Compressing pulses of a mode-locked extended-cavity Ti:sapphire laser using a standard single-mode fiber and tilted-front-interface
chirped mirrors yields phase-stabilized 4-fs, 3-nJ light pulses at the full, 24-MHz, repetition rate. The demonstrated source
paves the way towards exploring interactions sensitive to the carrier-envelope-offset phase, such as, for example, photoemission
from solid targets at moderate intensities (∼1012 W/cm2).
Received: 13 December 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +43-1/58801-38799, E-mail: apolonski@tuwien.ac.at 相似文献
7.
M.A. Rana T. Osipowicz H.W. Choi M.B.H. Breese F. Watt S.J. Chua 《Applied Physics A: Materials Science & Processing》2003,77(1):103-108
Annealling experiments were performed on GaN layers, grown on sapphire, over a wide range of temperatures (500–1100 °C). Rutherford
Backscattering Spectrometry (RBS) was performed in random and 〈0001〉 channelling geometries using 2 MeV protons and helium
ions to determine the stoichiometric and structural alterations produced during annealling. We present here, for the first
time, a comprehensive and quantitative analysis of the depth distribution of both stoichiometric and structural changes in
the near-surface region (∼750 nm) with a resolution of 50 nm for stoichiometric and 20 nm for structural changes. No decomposition
was measured for temperatures up to 800 °C. Decomposition in the near-surface region increased rapidly with further increases
in temperature, resulting in a near-amorphous region (500 nm) for annealling at 1100 °C. We describe the range of annealling
conditions under which negligible stoichiometric and structural changes are observed. Our nanoscale resolution results are
useful for the fabrication and operation of conventional and nanoscale optoelectronic and high-temperature devices.
Received: 23 December 2002 / Accepted: 16 January 2003 / Published online: 28 March 2003
RID="*"
ID="*"Corresponding author. Fax: +65-6777/6126, E-mail: scip0229@nus.edu.sg 相似文献
8.
The generation of programmable complex femtosecond pulses in the mid infrared (3–10 μm) with high precision is reported. Designed
pulse shapes in the near infrared (1–1.6 μm) are transferred to the mid infrared via difference-frequency mixing with a second
infrared pulse spectrally narrowed in a zero-dispersion compressor. In particular, pulse sequences with variable relative
phases have been obtained. The control of the pulse properties is achieved purely electronically, allowing for implementation
into a feedback loop.
Received: 12 December 2003 / Published online: 3 April 2003
RID="*"
ID="*"Corresponding author. Fax: +49-89/32905-200, E-mail: mcm@mpq.mpg.de 相似文献
9.
Study on the optimum mixing throat length for drive nozzle position of the central jet pump 总被引:1,自引:0,他引:1
The present paper describes a numerical prediction of optimum mixing throat length for various drive nozzle positions of the
central jet pump. The flow pattern and pressure distribution in the pump for various positions of the drive nozzle are investigated
by three-dimensional numerical analysis using the RNG k-ε turbulent flow model. Numerical analysis was carried out for values
of the nozzle throat ratiod/D of the jet pump of 0.5, 0.6 and 0.7, respectively. The static pressure in the flow field of the jet pump is calculated for
the following conditions: (1) drive nozzle position from the entrance of the throatl /D=0 ∼ 2.0, (2) flow rate ratioM=0∼ 1.2, and (3) Reynolds numberRe=3.6×105. These calculations revealed that (1) the optimum length of the mixing throat forl/D=0∼ 1.0 isLm/D=2.0 ∼ 3.5, (2) the length of the mixing throat forl/D=0 andM=0 (suction flow rate ratio=0) is approximatelyLm/D=3.5, and (3) the maximum efficiency is obtained ford/D=0.6 atl/D=0.5. Moreover, the flow pattern in the mixing throat is clarified through a spark tracing experiment. The results obtained
in the visualization experiment and the numerically obtained mixing length agreed well. 相似文献
10.
Ito S. Ishikawa H. Miura T. Takasago K. Endo A. Torizuka K. 《Applied physics. B, Lasers and optics》2003,76(5):497-503
We present a 7-TW Ti:sapphire laser system operating at 50 Hz for laser Compton femtosecond X-ray generation. This laser system
delivers 8.4 W of average output power at a repetition rate of 50 Hz with a pulse width of 24 fs. It demonstrates successful
management using a dynamically stable resonator in the regenerative amplifier and compensation for thermal lensing by a convex
mirror in a ring-type four-pass power amplifier. We also present the results of closed-loop corrections for distorted wavefronts
of amplified and compressed laser pulses, using an adaptive optical system consisting of a Shack–Hartmann-type wavefront sensor
and a deformable mirror. This closed-loop correction results in dramatic improvements, reducing wavefront distortions below
0.05 λ rms.
Received: 31 October 2002 / Revised version: 3 March 2003 / Published online: 5 May 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/61-3349, E-mail: ito@festa.or.jp 相似文献
11.
X. F. Yang D. Y. Shen T. Zhao H. Chen J. Zhou J. Li H. M. Kou Y. B. Pan 《Laser Physics》2011,21(6):1013-1016
We report on a high power polycrystalline Er:YAG ceramic laser in-band pumped by a cladding-pumped Er, Yb fiber laser wavelength
locked at 1532 nm with a volume Bragg grating. Using 1.0 at % Er3+-doped ceramic as the gain medium and an output coupler of 10% transmission, the laser had a threshold pump power of ∼1.5
W and generated 11 W of continuous-wave output at 1645 nm for 23.3 W of incident pump power at 1532 nm, corresponding to a
slope efficiency with respect to incident pump power of 51%. 相似文献
12.
A high-repetition-rate eye-safe optical parametric oscillator (OPO), using a non-critically phase-matched KTP crystal intracavity
pumped by an acousto-optically (AO) Q-switchedNd:YVO4 laser, is experimentally demonstrated. It is found that the average OPO signal power at 1573 nm can be efficiently increased
by increasing the pulse repetition rate. Moreover, the intracavity OPO process effectively shortens the pulse width so that
it is in the range 5∼8 ns for pulse repetition rates of 10 to 80 kHz. As a result of the relatively short pulse, the peak
power at 1573 nm is higher than 2 kW at a pulse repetition rate of 80 kHz.
Received: 10 July 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +886-35/729-134, E-mail: yfchen@cc.nctu.edu.tw 相似文献
13.
Ultrahigh-efficiency TEM00 operation is demonstrated in a diode-pumped Nd:YVO4 laser in a bounce amplifier geometry using a specially designed astigmatically optimised cavity configuration. Optical efficiency
>68% is demonstrated and up to 27.1 W of output power for multimode operation. For single-mode TEM00 operation, an output power of 23.1 W for 39.5 W of diode pumping was produced with beam propagation parameters of Mx
2=1.3 and My
2=1.1.
Received: 10 October 2002 / Revised version: 9 December 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: a.minassian@ic.ac.uk 相似文献
14.
15.
Multi-line laser transitions from one metastable triplet state to another at wavelengths of 2.92, 3.01, 2.69 and 2.60 μm have
been obtained through high pulse repetition frequency longitudinal discharge in a mixed gas of strontium vapor and helium
buffer gas. The intensity ratio of these laser lines was 5:4:4:1. As far as we know, these laser lines have never been reported
except for 3.01 μm. Some mechanisms for forming a population inversion are initially discussed on the basis of analyzing features
of corresponding energy-level structure and experimental phenomena. It is reasonable to name this kind of laser as an M–M
transition laser according to the feature of the lasing process.
Received: 15 October 2002 / Published online: 9 April 2003
RID="*"
ID="*"Corresponding author. Fax: +86-0571/8795-1328, E-mail: pbl66@zju.edu.cn 相似文献
16.
An analytical function involving four parameters is proposed to express the second-harmonic generation efficiency as well
as the parametric generation gain coefficient in the Boyd–Kleinman theory. The analytical function clearly reveals the dependence
of conversion efficiency on the focusing parameter and the walk-off parameter. Moreover, the optimum focusing parameter and
its corresponding maximum efficiency are explicitly given in the analytical function, leading to a straightforward evaluation
of a given crystal performance.
Received: 20 January 2003 / Published online: 22 May 2003
RID="*"
ID="*"Corresponding author. Fax: +886-35/7291-34, E-mail: yfchen@cc.nctu.edu.tw 相似文献
17.
Surface nanostructuring of silicon 总被引:1,自引:0,他引:1
A.J. Pedraza J.D. Fowlkes Y.-F. Guan 《Applied Physics A: Materials Science & Processing》2003,77(2):277-284
Irradiation with polarized laser light of 248-nm wavelength induces the formation of periodic undulations ∼10-nm-highon flat
silicon substrates. The wavelength of these periodic structures is a function of the light wavelength and the angle of incidence
of the laser beam. Linear arrays of silicon nanoparticles with fairly uniform size that extended up to a millimeter were formed
if the irradiation was performed using polarized light. When non-polarized laser light with the same fluence was used to illuminate
an initially flat surface, non-aligned nanoparticle strings were obtained. However, if part of the irradiated area was microstructured,
nanoparticle linear arrays resulted in the vicinity of the microstructured region. An analysis on the evolution of these nanostructures
is presented. Nanocolumns could be grown on top of every cone of a microstructured surface upon cumulative laser irradiation
with non-polarized light, reaching a height of ∼3 μm and a diameter of 100–200 nm. The mechanisms of nanocolumn origin and
growth are analyzed.
Received: 16 December 2002 / Accepted: 20 January 2003 / Published online: 28 May 2003
RID="*"
ID="*"Corresponding author. Fax: +1-865/974-4115, E-mail: apedraza@utk.edu 相似文献
18.
The authors’ endeavors over the last few years with respect to boron nitride (BN) nanotube metal filling are reviewed. Mo
clusters of 1–2 nm in size and FeNi Invar alloy (Fe ∼60 at. %; Ni ∼40 at. %) or Co nanorods of 20–70 nm in diameter were embedded
into BN nanotube channels via a newly developed two-stage process, in which multi-walled C nanotubes served as templates for
the BN multi-walled nanotube synthesis. During cluster filling, low-surface-tension and melting-point Mo oxide first filled
a C nanotube through the open tube ends, followed by fragmentation of this filling into discrete clusters via O2 outflow and C→BN conversion within tubular shells at high temperature. During nanorod filling, C nanotubes containing FeNi
or Co nanoparticles at the tube tips were first synthesized by plasma-assisted chemical vapor deposition on FeNi Invar alloy
or Co substrates, respectively, and, then, the nanomaterial was heated to the melting points of the corresponding metals in
a flow of B2O3 and N2 gases. During this second stage, simultaneous filling of nanotubes with a FeNi or Co melt through capillarity and chemical
modification of C tubular shells to form BN nanotubes occurred. The synthesized nanocomposites were analyzed by scanning and
high-resolution transmission electron microscopy, electron diffraction, electron-energy-loss spectroscopy and energy-dispersive
X-ray spectroscopy. The nanostructures are presumed to function as ‘nanocables’ having conducting metallic cores (FeNi, Co,
Mo) and insulating nanotubular shields (BN) with the additional benefit of excellent environmental stability.
Received: 10 October 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/51-6280, E-mail: golberg.dmitri@nims.go.jp 相似文献
19.
We report on a passively Q-switched diode-pumped Nd:YVO4 laser polarized along the a axis (corresponding to the smallest value of emission cross section at 1064 nm), generating 157-μJ
pulses with 6.0-ns time duration (>20 kW peak power) and 3.6 W of average power at 1064 nm with good beam quality (M2<1.4). The selection of the polarization was performed by a novel technique relying on the birefringence of the laser crystal
and on the misalignment sensitivity of the resonator.
Received: 30 September 2002 /
Revised version: 22 November 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +39-382/422583, E-mail: agnesi@ele.unipv.it 相似文献
20.
Efficient room-temperature operation of 4
F
3/24
I
9/2 transitions in diode-end-pumped Nd:YAG lasers at 946 nm and 938.5 nm is reported. 7.0-W continuous-wave output power at 946 nm
and 3.9 W at 938.5 nm have been obtained. An analytical model has been developed for the quasi-three-level laser including
the influence of energy-transfer upconversion. Frequency doubling of these transitions in periodically poled KTP generated
blue light at 473 nm and 469 nm. Both single-pass extra-cavity as well as intracavity schemes have been investigated.
Received: 31 July 2002 / Published online: 5 February 2003
RID="*"
ID="*"Corresponding author. Fax: +46-8/750-5430, E-mail: stefan.bjurshagen@acreo.se 相似文献