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1.
Ryoichi Kuwano Toshihiko Koga Tsuyoshi Tokunaga Toshitaka Wakayama Yukitoshi Otani Nobuyuki Fujii 《Optical Review》2012,19(2):98-102
In this study, a method for generating ring intensity distribution at a refraction-type lens with an aspheric element was
proposed, and the beam shaping optical element was finished using only ultra-precision cutting. The shape of the optical element
and its irradiance pattern were determined from numerical calculation based on its geometrical and physical optics. An ultra-precision
lathe was employed to fabricate beam shaping optical elements, and acrylic resin was used as the material. The transmittance
of an optical element (a rotationally symmetrical body) with an aspheric surface fabricated using a single-crystal diamond
tool was over 98%, and its surface roughness was 9.6 nm Ra. The method enabled the formation of a circular melting zone on
a piece of stainless steel with a thickness of 300 μm through pulse YAG laser (λ 1:06 μm) processing such that the average radius was 610 μm and the width was 100–200 μm. Circular processing using a ring
beam shaping optical element can be realized by single-pulse beam irradiation without beam scanning. 相似文献
2.
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
3.
4.
The optical torque and the trapping position (focal point) in optical tweezers are analyzed for upward-directed focused laser
illumination using a ray optics model, considering that laser light is incident at not only the lower surface but also the
side surface of a 3-wing rotor. The viscous drag force due to the pressure and the shearing stress on all surfaces of the
rotor is evaluated using computational fluid dynamics. The rotation rate is simulated in water by balancing the optical torque
with the drag force, resulting in 500 rpm for an SU-8 rotor with 20 μm diameter at a laser power of 200 mW. The trapping position
is estimated to be 7.6 μm in the rotor with an upward-directed laser at 200 mW via an objective lens having a numerical aperture
of 1.4. Both the rotation rate and the trapping position agree well with the values obtained in the experiment. 相似文献
5.
T.V. Kononenko S.V. Garnov S.M. Pimenov V.I. Konov V. Romano B. Borsos H.P. Weber 《Applied Physics A: Materials Science & Processing》2000,71(6):627-631
Laser ablation of thin TiN films deposited on steel substrates has been studied under wide-range variation of irradiation
conditions (pulsewidth, wavelength, energy density and spot size). It has been demonstrated that both picosecond (150–300 ps)
and nanosecond (5–9 ns) laser pulses were suitable for controllable ablation and microstructuring of a 1-μm-thick TiN film
unlike longer 150-ns pulses. The ablation rate was found to be practically independent of the wavelength (270–1078 nm) and
pulsewidth (150 ps–9 ns), but it increased substantially when the size of a laser spot was reduced from 15–60 μm to 3 μm.
The laser ablation technique was applied to produce microstructures in the thin TiN films consisting of microcraters with
a typical size of 3–5 μm in diameter and depth less than 1 μm. Tests of lubricated sliding of the laser-structured TiN films
against a steel ball showed that the durability of lubricated sliding increased by 25% as compared to that of the original
TiN film.
Received: 28 July 1999 / Accepted: 17 April 2000 / Published online: 20 September 2000 相似文献
6.
A regression approach is proposed for planning aerosol optical experiments and for estimating the potential accuracy of the
derived microphysical parameters of atmospheric aerosols taking the features of the apparatus and the available a priori information
into account. This method is used to evaluate the informativity of polarization spectronephelometer measurements with respect
to the microphysical parameters of continental aerosols. The problem of choosing the most informative aerosol optical characteristics
with respect to the mass concentrations of the PM
2.5 and PM
10 respirable fractions is examined and regression equations are derived for determining these concentrations from lidar probe
data at wavelengths of 0.355 and 1.064 μm, as well as from reference measurements at 0.37 and 0.98 μm. The theoretical results
obtained here are compared with AERONET data. 相似文献
7.
This paper presents a specially designed optical parametric oscillator (OPO) which achieved high-efficiency mid-infrared laser
of 2.83 μm. The cascaded nonlinear interactions of OPO and optical parametric amplifier (OPA) were simultaneously realized
in a single MgO:PPLN crystal. The signal oscillation of 1.70 μm was used to pump a secondary parametric process that resulted
in amplification of the idler laser of 2.83 μm. When the MgO:PPLN crystal with a grating period of 31.2 μm was pumped by a
1.064 μm laser and operated at 148°C, the quasi-phase-matching of both OPO and OPA could be simultaneously achieved. Average
output power of 7.68 W at 2.83 μm was obtained for 25 W of pump at 7 kHz. The power conversion efficiency of 2.83 μm laser
was 30.7%, which was evidently higher than common OPOs. 相似文献
8.
Hexagonal GaN prismatic sub-micro rods and cone nanowires have been synthesized in a large scale by a novel and controllable
space-confined growth method. The as-synthesized GaN products are highly crystalline with a wurtzite structure. The prismatic
rods have lengths of 15∼20 μm and diameters of 400∼500 nm enclosed by hexagonal smooth side surfaces and a pyramidal end.
And the cone nanowires have average diameters of 150∼200 nm and lengths up to several tens of μm with a cone tip. The photoluminescence
(PL) studies reveal prominent band-gap UV emission properties of GaN products and narrow FWHM, indicating the excellent luminescent
performance and high crystal quality. For field emission characteristic of GaN nanowires, the turn-on field is about 9.5 V/μm
and the current density reaches 1.0 mA/cm2 at an electric field of 18 V/ μm. The contrast experiments indicate a novel growth control can be achieved by using a graphite
tube as reaction vessel. The sealed graphite tube combined with metallic initiator is greatly responsible for large-scale
and uniform preparation of GaN prismatic rods and cone nanowires. Highly symmetric GaN hexagonal micropyramids are grown on
a bare Si substrate. The growth mechanism and the control function of the graphite tube are demonstrated. These low-dimensional
structures not only enrich semiconducting GaN family, but also are good building blocks for optoelectronic devices.
PACS 81.10.Bk; 81.07.-b; 81.05.Ea 相似文献
9.
K. V. Kalinina S. S. Molchanov N. D. Stoyanov A. P. Astakhova Kh. M. Salikhov Yu. P. Yakovlev 《Technical Physics》2010,55(2):258-263
An optical method for measuring the water and oil content using mid-IR (1.6–2.4 μm) LEDs and a wideband photodiode is suggested
for the first time. This method is developed based on the absorption spectra of pure water, dewatered oil, and water—oil emulsions
(cut oil) with different content of water and uses 10 types of LEDs in the spectral range 1.6–2.4 μm. It is shown that pure
water heavily absorbs the LED radiation in the spectral range 1.85–2.05 μm, oil absorbs in the range 1.67–1.87 μm, and the
LED radiation with a maximum at 2.20 μm is equally weakly absorbed by water and oil. An optical cell of the water-and-oil
analyzer is designed on the basis of a three-element diode array with radiation maxima at 1.65 (detection of oil), 1.94 (detection
of water), and 2.2 μm (reference signal) wideband photodiode covering the spectral range 1.3–2.4 μm. A calibration curve is
derived that represents the dependence of the water concentration in oil on the amplitude of the reduced signal obtained by
processing three signals from the LEDs. This optical method of measuring the water content in oil underlies a portable analyzer
making possible online measurements directly in an oil well. 相似文献
10.
Noriaki Onodera Kenichiro Tsuji Masaki Oiwa Syunsuke Minami Masatoshi Saruwatari 《Optical Review》2009,16(1):22-25
Less than 100ps, polarization-independent switching operation of an active birefringent optical fiber loop filter using 1.3
μm control optical pulses as well as a 1.3 μm semiconductor optical amplifier (SOA) has been demonstrated. In the proposed
SOA-based active birefringent filter operating at 1.55 μm wavelength, 1.3 μm SOA is employed to control the polarization-mode
dispersion in the loop part. By injecting 1.3 μm ps gain-switched optical control pulses into the SOA, 1.5 μm input signals
can be switched from the transmission port to the reflection port with less than 100 ps rise time. 相似文献
11.
A 50 cm silver coated hollow fiber with inner diameter of 250 μm and filled with argon has been used to compress optical pulses
from a Ti:sapphire laser at 800 nm. Input pulses with energy of 250 μJ and duration of 110 fs were used and compressed pulses
with energy of 220 μJ and duration of 20 fs were generated by using a prism compressor. Numerical and experimental results
are compared. There is good agreement between the measured beam diameters of the hollow-fiber output pulse and the calculated
values obtained from propagation of the HE11 mode into free space. For comparison, a similar uncoated fused-silica hollow fiber was also used to obtain 20 fs compressed
pulses with an energy of 190 μJ.
Received: 7 September 2002 / Published online: 26 March 2003
RID="*"
ID="*"Corresponding author. Fax: +1-780/492-1811, E-mail: mohebbi@ee.ualberta.ca 相似文献
12.
M. K. Bhuyan F. Courvoisier H. S. Phing O. Jedrkiewicz S. Recchia P. Di Trapani J. M. Dudley 《The European physical journal. Special topics》2011,199(1):101-110
We report the generation of femtosecond Bessel beams of conical half-angle 26 degrees using an axicon lens and a beam reduction
imaging setup. The generated Bessel beams were applied to the micromachining of nanostructures in glass of length up to 100 μm.
The effect of the incident pulse energy on the characteristics of the nano- structures was studied using optical microscopy. 相似文献
13.
S. Borodziuk A. Kasperczuk T. Pisarczyk S. Yu. Gus'kov J. Ullschmied E. Krousky K. Masek M. Pfeifer K. Rohlena J. Skala M. Kalal J. Limpouch P. Pisarczyk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):311-317
Efficiency studies of laser driven thin metal disks
acceleration using the first harmonic (λ1=1.315 μm) of
the Prague Asterix Laser System (PALS) and subsequent craters creation
produced by collisions of these disks with massive targets are presented.
Several different disks made of aluminium and copper foils with diameters of
300 μm and 600 μm and thicknesses of 11 μm (Al) and 3.6 μ
m (Cu) were employed. Disks were placed at the distance of either 100 μ
m or 300 μm in front of aluminium massive targets. The following
irradiation conditions were used: the laser beam energy of 120 J, the focal
spot diameter of 200 μm, and the pulse duration of 0.4 ns (FWHM). A
three-frame interferometric system was employed to determine electron
density distributions in plasma corona. Shape and volume of craters were
obtained by crater replica technology and microscopy measurements. The aim
of these investigations was to analyse conditions leading to the most
effective energy transfer in the process of collision of the accelerated
disks with solid targets. The overall efficiency of these processes was
characterized by the volume of craters produced in such targets. 相似文献
14.
Fatemeh Abrishamian Shinichi Nagai Shinya Sato Masaaki Imai 《Optical and Quantum Electronics》2008,40(9):665-676
Spectral response of acoustically induced microbending through thin optical fiber is discussed from mode-coupling of core
and cladding modes. The thin fiber is analyzed in three-layered structure (core-cladding-air) to gain insights into acousto-optic
modulation. We explained the dependence of core and/or cladding diameters on acoustic source parameters from numerical calculations.
According to the calculations, we successfully fabricated all-optical tunable filter using this thin fiber that yields an
efficient mode-coupling at flexural wave frequencies less than 1MHz. To increase the acousto-optic effect, we used a specially
designed thin optical fiber (80 μm of cladding diameter) in the section where flexural wave is produced, and spliced both
ends of the thin fiber to the tapered 125 μm fibers. The frequency and voltage tuning of fabricated filter is also confirmed
by changing the driven frequency and applied voltage of the PZT, respectively. This result suggests a possibility of fiber-optic
device application as all-optical tunable filter at 1.55 μm. 相似文献
15.
We report a compact and viable source of high-efficiency, high-repetition-rate, temperature-tuning, mid-IR optical parametric
oscillator (OPO) based on periodically poled MgO-doped lithium niobate (PPMgOLN) pumped by a homemade high power AOM Q-switched
Nd:YVO4 laser centered at 1.064 μm. With an optimal plane-concave resonator configuration, average output power of 5.7 W at 2.73
μm was obtained when the pump power was 25 W at the repetition rate of 80 kHz. The conversion efficiency from the 1.064 μm
laser to the 2.73 μm laser was 22.8%. Temperature tuning of the OPO yielded a signal wavelength range from 1.67 to 1.75 μm
and an idler wavelength in the range of 2.72 to 2.92 μm. 相似文献
16.
An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection
grating is proposed to simultaneously realize functions of wavelength demultiplexing and optical signal distribution in a
multimode optical fiber transmission system. We analyzed the demultiplexing characteristics and the tolerance of optical components
using the ray trace method. This device can realize not only low loss optical signal distribution but also offers improved
demultiplexing characteristics in comparison with the previously proposed demultiplexer-multiposition switch. The following
characteristics are expected from the design using commercially available optical components: a working band of 0.64–0.88
μm, channel separation of 34–36 nm, 3 dB bandwidth of 27–28 nm, channel cross-talk of less than - 40 dB and minimum excess
insertion loss of 0.9–2.1 dB. 相似文献
17.
飞秒激光在光敏玻璃内制作微孔 总被引:1,自引:1,他引:0
用20倍显微物镜将波长为775 nm的飞秒激光聚焦在光敏玻璃(FOTURAN)内部,通过纵向写制模式由表面以下500 μm曝光至表面,并结合热处理和在浓度8%的氢氟酸超声溶液中腐蚀50 min,在FOTURAN内部制作了直径为几十μm的微孔.利用光学和扫描电子显微镜分析发现微孔具有圆形横截面和清晰边缘,目前得到的深宽比大约为7.通过在宽范围内改变入射激光能流(2.3~36.2 J/cm2)和写制速度(100~1 000 μm/s),研究了这两项飞秒激光入射参量对制作微孔的影响.发现写制速度对制作微孔直径影响较小,而利用相对低的入射激光能流曝光可得到较大深宽比的微孔,并且在此情形下制作微孔的横截面更圆,璧面光滑度更高,并分析了原因. 相似文献
18.
N. N. Il’ichev P. V. Shapkin E. S. Gulyamova A. V. Kir’yanov A. S. Nasibov 《Laser Physics》2010,20(5):1091-1094
Effective lasing is obtained in the transversely pumped ZnSe single crystals that are doped with Cr2+ ions using diffusion methods. A Q-switched Er3+-doped glass laser with a radiation wavelength of 1.54 μm is used for pumping. The resulting laser energy is 150 μJ at an
absorbed pump energy of 600 μJ, so that the efficiency is 25% and the slope efficiency is 29%. An increase in the gain (up
to the superluminescence level) due to the application of the transverse pumping of the active element with a substantially
non-uniform distribution of the dopant is discussed. 相似文献
19.
A micrometer-size solid immersion lens (μ-SIL) of glass with a super-spherical shape is obtained using a simple preparation procedure. Soda-lime–silica glass particles are melted on a glassy-carbon substrate with a surface of optical grade and cooled to room temperature. The obtained glass particles are transparent and have a super-spherical shape. Their shapes are found to satisfy the conditions of the SIL function for evanescent-field optics. Fine uneven surface textures of an integrated circuit with the depth of about 20 nm are clearly recognized using the prepared μ-SIL, and 1.8 times higher horizontal resolution than without the μ-SILis also attained. It was ensured that the glass μ-SILworks as the evanescent-field optics to visualize the nanometer-scale structure. PACS 42.70.Ce; 42.79.Bh; 68.03.Cd; 68.08.Bc; 68.37.Uv 相似文献
20.
We present a vision chip architecture with column-level photo-amplification of optical data signals for optical wireless local
area networks (LANs) to reduce the pixel area. Based on the architecture, we have fabricated a prototype vision chip in a
standard 0.8 μm bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. The device offers position detection
of other optical transceivers in the LAN and 4-ch concurrent high-speed optical data acquisition. A data rate of 400 Mbps
was demonstrated. The pixel size was 125 μm square, which can be shrunk to smaller than around 60 μm square in 0.35 μm or
more advanced BiCMOS or CMOS technologies. 相似文献