共查询到20条相似文献,搜索用时 250 毫秒
1.
S. Longhi M. Marano P. Laporta O. Svelto R. Corsini F. Fontana 《Applied physics. B, Lasers and optics》1999,69(5-6):487-490
A detailed experimental analysis of the amplitude noise in high-repetition-rate picosecond pulse trains generated by spectral
filtering of a frequency-modulated Er-Yb:glass laser is reported. Two distinct sources of noise are identified, and stabilization
techniques for noise suppression are proposed and experimentally demonstrated. Intensity noise suppression of ∼20 dB, corresponding
to less than 2% residual amplitude fluctuations of the pulse train, has been achieved at repetition rates of 2.5 GHz and 5 GHz
with pulse durations of ∼50 ps.
Received: 28 July 1999 / Revised version: 13 September 1999 / Published online: 20 October 1999 相似文献
2.
A schlieren method was used to generate time-resolved images of the tunneling ionization front produced when an ultrashort
high-power laser pulse irradiates He gas. By superimposing sequential schlieren images, we obtained information about the
laser propagation and found that the ionization front propagated farther with decreasing density of the target gas. Ray-tracing
suggested that this density dependence is a result of the spatial distribution of the laser intensity.
Received: 20 May 1999 / Revised version: 19 August 1999 / Published online: 27 January 2000 相似文献
3.
G. Fuhr C. Reichle T. Müller K. Kahlke K. Schütze M. Stuke 《Applied Physics A: Materials Science & Processing》1999,69(6):611-616
An electric cage-laser micro-turning lathe was realised and applied to contact-free handling and mechanical processing of
micro particles. Since particles with diameters of several micrometers cannot be fixed in mechanical chucks, an octode field
cage was used to trap and rotate a single particle in a fluid without any mechanical surface contact. A pulsed nitrogen laser
of high beam quality focused to about 1 μm in diameter could be adjusted independently of the cage position. The trapping
forces (negative dielectrophoresis) acting on a bead of 5 to 15 μm are up to several hundred pN. This and the surrounding
fluid damp down the effect of the laser pulses during bead processing. Examples demonstrating the possibilities of this technique
are shown. Microsystems with high optical quality were fabricated photolithographically or by laser direct-write chemical
vapor deposition (LCVD). Technical and biotechnological applications are discussed.
Received: 20 October 1999 / Accepted: 27 October 1999 / Published online: 10 November 1999 相似文献
4.
M. Grundmann F. Heinrichsdorff C. Ribbat M.-H. Mao D. Bimberg 《Applied physics. B, Lasers and optics》1999,69(5-6):413-416
The field of semiconductor quantum dot (QD) diode lasers is rapidly developing. Important milestones, such as low-threshold
operation and room-temperature cw operation, have been achieved in the last years. We review the progress in theoretical understanding
and present recent results on high-power QD laser operation (>3 W@1100 nm).
Received: 24 June 1999 / Revised version: 23 August 1999 / Published online: 20 October 1999 相似文献
5.
W.J. Wadsworth I.T. McKinnie A.D. Woolhouse T.G. Haskell 《Applied physics. B, Lasers and optics》1999,69(2):163-165
We present the first operation of a distributed feedback solid state dye laser with a dynamic, pump-induced grating. Broadly
tunable, narrow band operation in the region of 616 nm (604–649 nm) has been demonstrated with perylene red laser dye doped
in poly(methyl methacrylate) (PMMA), when pumped with a frequency doubled Nd:YAG laser. Conversion efficiencies of 20%, corresponding
to 35% optical-to-optical efficiency, have been measured. The laser bandwidth was between 0.01 and 0.04 nm, and smooth tuning
over more than 200 GHz has been demonstrated.
Received: 29 March 1999 / Published online: 24 June 1999 相似文献
6.
G. Bánó L. Szalai K. Kutasi P. Hartmann Z. Donkó K. Rózsa Á. Kiss T.M. Adamowicz 《Applied physics. B, Lasers and optics》2000,70(4):521-525
Single-mode operation at the Au-II 690-nm transition was obtained in a segmented hollow-cathode discharge laser without the
use of any additional frequency-selective device. The pressure of the helium buffer gas, which is responsible for the significant
homogeneous broadening of the laser line, was varied between 10 and 20 mbar. The discharge was excited with rectangular current
pulses (up to 3 A) six times exceeding the threshold value. The time dependence of the laser output during the 1-ms-long discharge
pulses is explained on the basis of the temperature and pressure changes in the tube. The highest small-signal gain at optimal
discharge conditions was 11%m−1.
Received: 1 July 1999 / Revised version: 4 November 1999 / Published online: 23 February 2000 相似文献
7.
S. Gloor V. Romano W. Lüthy H.P. Weber V.V. Kononenko S.M. Pimenov V.I. Konov A.V. Khomich 《Applied Physics A: Materials Science & Processing》2000,70(5):547-550
Two-dimensional antireflective periodical microstructures for the IR range are fabricated on the surface of CVD diamond films.
These structures are created using an ArF excimer laser (λ=193 nm) and a direct writing scheme consisting of a beam collimator
and a microscope objective to focus the beam onto the sample. Two different arrays are investigated. One has a spacing of
3 μm and is produced with single shots and the other one has a spacing of 4 μm and is produced with three shots per spot.
The hole depth and shape are measured with an atomic force microscope (AFM). The optical transmittance and the scattering
properties of the structure at 10.6 μm are reported for a CO2 laser beam. With a spectrometer further transmission measurements in the range of 5 to 20 μm are performed.
Received: 16 September 1999 / Accepted: 11 October 1999 / Published online: 24 March 2000 相似文献
8.
Lasing mechanism in two-dimensional photonic crystal lasers 总被引:2,自引:0,他引:2
A. Mekis M. Meier A. Dodabalapur R.E. Slusher J.D. Joannopoulos 《Applied Physics A: Materials Science & Processing》1999,69(1):111-114
We conduct a comprehensive investigation of the lasing mechanism in a photonic crystal slab laser with a refractive index
that is periodic in two dimensions. Experimental spectra of laser structures fabricated with organic gain media are presented.
It is found that lasing frequencies can be explained in terms of Van Hove singularities in the density of modes. We also observe
lasing spectra that cannot be obtained from structures with one-dimensional periodicity, such as traditional distributed feedback
lasers. Lasing frequencies are computed using numerical techniques.
Received: 7 April 1999 / Accepted: 12 April 1999 / Published online: 19 May 1999 相似文献
9.
X. Chen 《Applied Physics A: Materials Science & Processing》1999,69(4):453-455
We have observed a new polarisation pattern in terbium gallium garnet which is both laser excited and mechanically stressed.
The pattern can be characterized by a splitting from a “one dot” structure to a “two dots” structure. We have found that the
new pattern is very sensitive to the orientation and the strength of the external forces applied to the sample. Thanks to
this sensitivity and to the image simplicity, this new effect may be used in a vectorial force sensor and actuator.
Received: 25 March 1999 / Accepted: 20 April 1999 / Published online: 25 August 1999 相似文献
10.
Narrow bandwidth operation of high-power broad-area diode laser using cascaded phase-conjugate injection locking 总被引:1,自引:0,他引:1
H. Horiuchi T. Shimura T. Omatsu O. Matoba K. Kuroda 《Applied physics. B, Lasers and optics》1999,68(5):1021-1025
A broad-area laser is injection-locked by another broad-area laser that is also injection-locked by a single-mode diode laser.
Two double-phase conjugate mirrors of photorefractive BaTaO3 are used to couple the master laser beams to the first slave laser, and the first slave laser output to the second slave
laser. One of the double-phase conjugate mirrors is built up with the beams from two broad-area lasers. Two slave lasers are
oscillating in single longitudinal mode at 808.5 nm and the spectral width is the same as that of the master laser. Final
single-mode output power from the second slave broad-area laser is 840 mW, which is limited by the power of the injection
beam. This work verifies the possibility of the multi-stage cascaded injection locking of high-power diode lasers with phase-conjugate
injection.
Received: 18 November 1998 / Revised version: 29 January 1999 / Published online: 7 April 1999 相似文献
11.
D.C. Meyer A. Klingner Th. Holz P. Paufler 《Applied Physics A: Materials Science & Processing》1999,69(6):657-659
After aging at room temperature for several months W/C multilayers (20 periods, single layer thicknesses in the nanometer
range) grown on Si-(111) substrates by pulsed laser deposition (PLD) developed homogeneously wrinkled surfaces. Their structures
were studied by optical microscopy, atomic force microscopy and X-ray diffractometry. Typical dimensions of debonded areas
are some 100 μm in length, about 40 μm in width and 2–3 μm in height. The formation of wrinkles is accompanied by an increase
in the free surface by 1–2%. Stress relaxation is considered the driving force of this phenomenon.
Received: 26 July 1999 / Accepted: 29 July 1999 / Published online: 16 September 1999 相似文献
12.
R.A. Gunasekaran J.D. Pedarnig M. Dinescu 《Applied Physics A: Materials Science & Processing》1999,69(6):621-624
A parametric study of the growth of La0.5Sr0.5CoO3 (LSCO) thin films on (100) MgO substrates by pulsed-laser deposition (PLD) is reported. Films are grown under a wide range
of substrate temperature (450–800 °C), oxygen pressure (0.1–0.9 mbar), and incident laser fluence (0.8–2.6 J/cm2). The optimum ranges of temperature, oxygen pressure, and laser fluence to produce c-axis oriented films with smooth surface morphology and high metallic conductivity are identified. Films deposited at low
temperature (500 °C) and post-annealed in situ at higher temperatures (600–800 °C) are also investigated with respect to their
structure, surface morphology, and electrical conductivity.
Received: 20 November 1998 / Accepted: 6 July 1999 / Published online: 21 October 1999 相似文献
13.
We demonstrate monitoring of H2O and CO2 emitted in a volcanic area, using a spectrometer equipped with two distributed feedback (DFB) semiconductor diode lasers.
Each laser is resonant with a molecular species and is fiber-coupled to allow remote operation of the spectrometer. Recordings
of H2O and CO2 lines made at the Solfatara volcano, in southern Italy, are shown, and the application of such a spectrometer as a new tool
for the continuous monitoring and surveillance of volcanoes is discussed.
Received: 28 June 1999 / Revised version: 20 December 1999 / Published online: 23 February 2000 相似文献
14.
Atom lithography with a cold, metastable neon beam 总被引:1,自引:0,他引:1
P. Engels S. Salewski H. Levsen K. Sengstock W. Ertmer 《Applied physics. B, Lasers and optics》1999,69(5-6):407-412
We study different aspects of atom lithography with metastable neon atoms. Proximity printing of stencil masks is used to
test suitable resists that are sensitive to the internal energy of the atoms, including dodecanethiols on gold and octadecyltrichlorosilanes
grown on a SiO2 surface. As an example of patterning the atomic beam with laser light, we create parallel line structures on the surface
with a periodicity of half the laser wavelength by locally de-exciting the atoms in a standing quenching wave.
Received: 29 June 1999 / Revised version: 30 August 1999 / Published online: 10 November 1999 相似文献
15.
Modeling of UV pulsed-laser ablation of metallic targets 总被引:1,自引:0,他引:1
S. Amoruso 《Applied Physics A: Materials Science & Processing》1999,69(3):323-332
A model to describe the laser ablation of metallic targets is presented. It accounts for the main physical processes involved
in the laser–solid–plasma interaction by considering the photon absorption and the ionization mechanisms that are active in
the plasma, as well as the laser-produced plasma kinetics. The model is used to simulate the laser ablation of aluminum targets
irradiated with a 6-ns UV laser pulse at 0.35 μm, and the results are compared with experimental findings. Calculations show
that all the investigated plasma parameters strongly depend on the laser intensity until a roll-off is reached at irradiance
≥1.5 GW cm-2. The satisfactorily good agreement between model predictions and experimental findings confirms that laser–plasma interaction
processes and plasma kinetics play a relevant role during nanosecond laser ablation of metals in the laser intensity range
of concern in this study.
Received: 12 February 1999 / Accepted: 12 April 1999 / Published online: 7 July 1999 相似文献
16.
F. Beinhorn J. Ihlemann K. Luther J. Troe 《Applied Physics A: Materials Science & Processing》1999,68(6):709-713
Micro-lenses with well-defined optical parameters are generated on polymethylmethacrylate (PMMA) substrates doped with diphenyltriazene
(DPT) by controlled use of a swelling effect generated under conditions of subablative excimer laser illumination. The surface
profiles depend on the laser spot size and energy density. A sensitively balanced combination of matrix softening, substrate
volume expansion due to photochemical nitrogen release, and surface tension is responsible for the final shape of the lenses.
Complete arrays of identical lenses with 15 μm diameters and a focal length of 30 μm are produced by irradiation of (0.25 wt. %)
DPT-PMMA with a single laser pulse at a wavelength of 308 nm and a fluence of 3 J/cm2. It is shown experimentally and theoretically that appropriate volume expansion is possible without introducing internal
light scattering due to the formation of small bubbles.
Received: 7 April 1999 / Accepted: 8 April 1999 / Published online: 5 May 1999 相似文献
17.
A new regime of chemical oxygen-iodine laser (COIL), high-pressure subsonic mode operation, was demonstrated using a jet-type
singlet oxygen generator (SOG). The laser output power of 342 W with chemical efficiency of 20.9% was obtained at the Cl2 flow rate of 18 mmol/s and the operating pressure of 6.4 Torr in the laser cavity. The specific energy was 3.1 J/l which
was four times higher than our supersonic device, and was comparable to the highest value for the supersonic regime. The experimental
results were in good agreement with the numerical simulation results.
Received: 26 February 1999 / Revised version: 13 July 1999 / Published online: 30 November 1999 相似文献
18.
Laser polishing of diamond plates 总被引:5,自引:0,他引:5
S.M. Pimenov V.V. Kononenko V.G. Ralchenko V.I. Konov S. Gloor W. Lüthy H.P. Weber A.V. Khomich 《Applied Physics A: Materials Science & Processing》1999,69(1):81-88
Results are reported on laser polishing of 150–400-μm-thick free-standing diamond films with either a copper vapor laser (510 nm
wavelength) or an ArF excimer laser (193 nm wavelength). Studies were focused on three particular goals. First, we aimed at
a choice of optimum conditions for laser polishing of thick diamond films. It was shown that the laser polishing conditions
and the resulting surface roughness were controlled by varying the angle of incidence of a scanning laser beam and by polishing
time. Second, the laser ablation technique was applied to remove a defective layer from the “substrate” side of the diamond
plates in order to reduce optical losses due to absorption in this layer. Third, the structure of the laser-graphitized diamond
surface was studied using UV, visible, and IR optical spectroscopy techniques in the course of the “step-by-step” oxidative
removal of the graphitic layer with increasing temperature of the oxidation in ambient air. Once the graphitic layer was removed,
the optical transmission in the UV-visible-IR spectral range of the diamond films polished under optimum conditions was measured
and compared with the optical transmission of the mechanically polished diamond films. It was shown that the optical quality
(in the long-wave infrared region) of the laser-polished diamond plates was sufficient to reach the transmittance value very
close to the theoretical limit.
Received: 20 October 1998 / Accepted: 8 March 1999 / Published online: 5 May 1999 相似文献
19.
W. Shuicai Z. Changjun H. Junfang Y. Hongru X. Dong H. Xun 《Applied physics. B, Lasers and optics》1999,69(3):211-216
We report the theory and experiments of a two-wavelength bi-tuning femtosecond Ti:sapphire laser. The cross-mode-locked gain
competition is described with numerical solution and operation of the laser is accomplished in which two trains of femtosecond
pulses cross in the Ti:sapphire rod. For this reason, a cross-bearings technique is used. The laser resonator is a six-mirror
bi-cavity, and two beams of pump lights cross in Ti:sapphire crystal. Two trains of sub-30 fs cross-mode-locked pulses have
been generated with independent tunable wavelength when the pump power of the argon laser is approximately 5 W. As the design
of the bi-cavity is fine, not only strong gain competition is overcome, but also stable output characteristics are performed.
Received: 21 July 1998 / Revised version: 5 January 1999 / Published online: 30 July 1999 相似文献
20.
H. Leinen D. Glässner H. Metcalf R. Wynands D. Haubrich D. Meschede 《Applied physics. B, Lasers and optics》2000,70(4):567-571
We have characterized the spectroscopic properties of one of the first samples of blue-emitting diode lasers based on GaN.
With such a laser diode operated inside a standard extended cavity arrangement we find a mode-hop free tuning range of more
than 20 GHz and a linewidth of 10 MHz. Doppler-free spectroscopy on an indium atomic beam reveals the isotope shift between
the two major indium isotopes as well as efficient optical pumping.
Received: 8 November 1999 / Revised version: 31 January 2000 / Published online: 8 March 2000 相似文献