共查询到20条相似文献,搜索用时 15 毫秒
1.
Lian F. Q. Fan Zh. W. Wang X. F. Huang Y. T. Huang K. Ma Y. F. Niu G. Li X. H. Yu J. 《Laser Physics》2011,21(6):1103-1107
In this paper, we describe a compact all-fiber-path picosecond pulse based on Ytterbium doped fiber oscillator. A home-made
novel SESAM mounted on fiber is reported, by which stable mode locking is obtained. The SESAM possesses the low saturation
flux 20 μJ/cm2 (versus prior low saturation flux 32 μJ/cm2), which effectively reduces the pump power threshold of mode locking. The fiber laser generates 15 ps pulse trains without
a dispersive delay line or anomalous dispersion in the cavity. Mode locking pulse with 30 MHz basic repetition-rate was produced,
with 10–30 mW scale average output power at 1064 nm. Through 60 h of uninterrupted laser operating, mode locking is steady
as ever. 相似文献
2.
V.G. Savitski N.N. Posnov P.V. Prokoshin A.M. Malyarevich K.V. Yumashev M.I. Demchuk A.A. Lipovskii 《Applied physics. B, Lasers and optics》2002,75(8):841-846
Passive mode locking and saturable absorber Q-switching of neodymium lasers at 1.3 μm with PbS-doped phosphate glasses are
demonstrated. Q-switched pulses of 120 ns (0.1 μJ) in duration (energy) and the average output power of 3 mW from a quasi-cw
diode-pumped Nd3+:KGW laser and ultrashort pulses of a maximum of 250 μJ in energy and 150 ps in duration from a Nd3+:YAP laser were obtained. The bleaching decay rate of the samples was found to increase with the Quantum Dot’s size decreasing
due to the enhancement of quantum confinement effects for smaller dots and stronger overlapping of the electron and trap state
wave functions.
Received: 23 January 2002 / Revised version: 2 April 2002 / Published online: 20 December 2002
RID="*"
ID="*"Corresponding author. Fax: +375-17/232-6286, E-mail: savitski@eudoramail.com 相似文献
3.
The efficient cw mode locking (cw-ML) regime was demonstrated in Nd:YVO4 laser by means of saturable absorber mirror (SAM). The 0.3-at.% Nd3+ doped 10-mm-long YVO4 crystal end pumped by 20-W diode module with a beam shaper was applied as a gain medium located in the close vicinity to
the rear flat mirror of the first arm of Z-type resonator of 316 cm total length with two curved mirrors of 100-cm curvature
radii. The SAM of 2%-saturable absorptance and saturation fluence of 50 μJ/cm2 was mounted at the opposite end of a resonator. The developed “dynamically stable” cavity design mitigates detrimental role
of thermal aberration in gain medium, enforcing clean perfect mode locking even for the highest pump densities. The cw-ML
pulses with 47.5 MHz repetition rate and pulse durations in the range of 15–20 ps were observed for a wide range of pump powers
and output coupler losses. In the best case, for 32% of output coupler transmission, up to 6.2 W of average power with near
35% slope efficiency was achieved. The thresholds for Q-switched ML, cw-ML regimes were 2.67 W and 6.13 W of pump power, respectively.
For the maximum pump power of 20 W we obtained 133 nJ of pulse energy with 16-ps pulse duration, resulting in a peak power
higher than 8 kW. The threshold energy density at SAM giving the QML regime was estimated to be about 30 μJ/cm2, threshold of cw-ML regime was 220 μJ/cm2. 相似文献
4.
Yong Gang Wang Hou Ren Chen Xiao Min Wen Wen Feng Hsieh Jau Tang 《Optics Communications》2012,285(7):1891-1894
A novel and low-cost wall paper single-walled carbon nanotubes (SWCNTs) absorber was fabricated by high viscosity of polyvinyl alcohol (PVA) aqueous solution and vertical evaporation technique. Sandwich structure wall paper SWCNT (SSWA-SWCNT) absorber was constructed by a piece of wall paper SWCNT absorber, a piece of round quartz and an output coupler mirror. We exploited it to realize mode locking operation in a diode-pumped Nd: GdVO4 laser. A pulse duration of 9.6 ps was produced with an average power of 870 mW. The stable mode locking operation was obtained when the average power is less than 300 mW. 相似文献
5.
A low-cost multiple-walled carbon nanotubes/polyvinyl alcohol (MWCNTs/PVA) absorber was fabricated by the characteristics of high viscosity in large molecule PVA aqueous solution and vertical evaporation technique. Sandwich structured MWCNT/PVA absorber was constructed by a piece of MWCNT absorber, a piece of round quartz and a piece of reflective mirror. We exploited it to realize Q-switched mode locking operation in a diode-pumped Nd:YVO4 laser. The maximum average output power is about 630 mW. 相似文献
6.
A. A. Sirotkin L. Di Labio A. I. Zagumennyi Yu. D. Zavartsev S. A. Kutovoi V. I. Vlasov W. Lüthy T. Feurer A. A. Onushchenko I. A. Shcherbakov 《Applied physics. B, Lasers and optics》2009,94(3):375-379
The use of glasses doped with PbS nanocrystals as intracavity saturable absorbers for passive Q-switching and mode locking
of c-cut Nd:Gd0.7Y0.3VO4, Nd:YVO4, and Nd:GdVO4 lasers is investigated. Q-switching yields pulses as short as 35 ns with an average output power of 435 mW at a repetition
rate of 6–12 kHz at a pump power of 5–6 W. Mode locking through a combination of PbS nanocrystals and a Kerr lens results
in 1.4 ps long pulses with an average output power of 255 mW at a repetition rate of 100 MHz. 相似文献
7.
In this study, a swept-source optical coherence tomography (SS-OCT) system with a Fourier domain mode locking (FDML) laser
is proposed for a dermatology study. The homemade FDML laser is one kind of frequency-sweeping light source, which can provide
output power of >20 mW and an output spectrum of 65 nm in bandwidth centered at 1300 nm, enabling imaging with an axial resolution
of 12 μm in the OCT system. To eliminate the forward scans from the laser output and insert the delayed backward scans, a
Mach-Zehnder configuration is implemented. Compared with conventional frequency-sweeping light sources, the FDML laser can
achieve much higher scan rates, as high as ∼240 kHz, which can provide a three-dimensional imaging rate of 4 volumes/s. Furthermore,
the proposed high-speed SS-OCT system can provide three-dimensional (3D) images with reduced motion artifacts. Finally, a
high-speed SS-OCT system is used to visualize hair follicles, demonstrating the potential of this technology as a tool for
noninvasive diagnosis of alopecia. 相似文献
8.
F. Wang D. Z. Zhong Z. M. Wu G. Q. Xia R. F. Li 《International Journal of Infrared and Millimeter Waves》2006,27(12):1595-1601
Based on the self-reproduction theory, a rational harmonic mode-locked semiconductor optical amplifier fiber ring laser was
numerically investigated. The system parameters effects on pulse-amplitude equalization of rational harmonic mode locking
was analyzed and the numerical result shows that the 2∼5 order rational harmonic mode-locked pulse with the small amplitude
ripple can be obtained only by adjusting the system parameters. 相似文献
9.
10.
Piotr Kwiek 《Optics Communications》2010,283(10):2224-2227
The phenomenon of light diffraction by a cylindrical ultrasonic wave has been investigated. The diffraction was applied in a new type of acousto-optic modulator used for laser mode locking. The paper describes the modulator and presents results on mode locking of argon ion laser. The mode locking was obtained by means of a cylindrical acoustic wave launched in water at the frequencies of ultrasound 33-34 MHz. A standing wave regime of operation of the modulator resulted in a reliable generation of laser pulses with the duration 720 ps. 相似文献
11.
E. I. Kats V. V. Lebedev S. V. Malinin 《Journal of Experimental and Theoretical Physics》1998,86(6):1149-1155
Dynamics of double membrane films is investigated in the long-wavelength limit qh≪1 (q is the wave vector, and h is the thickness of the film) including the overdamped squeezing mode. We demonstrate that thermal fluctuations essentially
modify the character of the mode due to its nonlinear coupling to the transverse shear hydrodynamic mode. The renormalization
can be analyzed if the condition g≪1 is satisfied (where g∼T/κ, T is the temperature, and κ is the bending modulus). The corresponding Green’s function acquires as a function of the frequency ω a cut along the imaginary semiaxis. At
the effective length of the cut is ∼Tq
3/η (where η is the shear viscosity of the liquid). At
the fluctuations lead to an increase in the attenuation of the squeezing mode: it is larger than the ‘bare’ value by a factor
. We also present the analysis of the elastic modes.
Zh. éksp. Teor. Fiz. 113, 2096–2108 (June 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
12.
An xenon-lamp-pumped passively Q-switched and mode-locked (QML) Nd:YAG laser with Co:LMA saturable absorber at 1.3 μm is realized
in a straight cavity. The modulation depth of mode locking pulse has reached 100%. The pulse energy and the pulse width of
QML laser have been measured. The pulse width of the mode-locking laser is estamated to be 940 ps. 相似文献
13.
14.
P. Kula A. Spadło J. Dziaduszek M. Filipowicz R. Dąbrowski J. Czub S. Urban 《Opto-Electronics Review》2008,16(4):379-385
Compounds with moderate and large negative dielectric anisotropy (Δɛ) are very attractive liquid crystal (LC) for vertical
alignment mode (VA). Materials with such properties can be achieved by lateral substitution of a polar group into a mesogenic
molecule. We synthesized some new LC materials with a negative value of Δɛ, a moderately high birefringence (Δn), and a low
viscosity. The mesomorphic and physical behaviour of the novel biphenyls, terphenyls and quaterphenyls fluorosubstituted in
the rigid core and also with fluorinated alkyl and alkoxy chains are investigated. The prepared series of four LC compounds
are promising for new LC mixtures for various applications. Examples of nematic mixtures with Δɛ∼−3.25 will be presented. 相似文献
15.
V. G. Ostroumov F. Heine S. Kück G. Huber V. A. Mikhailov I. A. Shcherbakov 《Applied physics. B, Lasers and optics》1997,64(3):301-305
An intracavity frequency-doubled 10%Nd : LaSc3(BO3)4 (Nd : LSB) laser was investigated in different resonator configurations and in different operation modes under continuous
wave (cw) and quasi-cw laser-diode pumping. With a Cr4+ : YAG passive modulator and a KTP crystal the second-harmonic output power at 531 nm amounted to 190 mW in Q-switched TEM00 mode at 750 mW of pump power. In a sandwich resonator, when all the optical elements were in direct contact with each other,
0.8 W of green output power was obtained in cw mode under 2.7 W of pump power with a slope efficiency of 44%. In the same
setup under fiber-coupled diode-laser array pumping (5.6 W of incident power), 1.2 W of green output power was achieved in
cw mode and 1.4 W in quasi-cw mode.
Received: 30 April 1996/Revised version: 1 July 1996 相似文献
16.
G. Puentes 《Applied physics. B, Lasers and optics》2012,107(1):11-16
We present a simple and flexible frequency offset locking scheme developed for high-field imaging of ultra-cold atoms which
relies on commercially available RF electronics only. The main new ingredient is the use of the sharp amplitude response of
a “home-made” RF filter to provide an error signal for locking the lasers. We were able to offset lock two independent diode
lasers within a capture range of hundreds of MHz, and with a tuning range of up to 1.4 GHz. The beat-note residual fluctuations
for offset locked lasers are below 2 MHz for integration times of several hundreds of seconds. 相似文献
17.
S. Longhi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):57-66
Multiphase patterns are found in a mean-field model of a singly-resonant optical parametric oscillator that converts a pump
field at frequency 3ω into signal and idler fields at frequencies 2ω and ω. A complex Ginzburg-Landau equation without diffusion
and with a quadratic phase-sensitive nonlinear term is derived under single-longitudinal and paraxial propagation approximations.
Owing to the phase-matched multistep parametric process ω + ω = 2ω, phase locking of the resonated signal field is possible
with three distinct phase states. Three-armed rotating spirals, target patterns and light filamentation are found by a numerical
analysis of the mean-field equation.
Received 19 April 2001 and Received in final form 21 June 2001 相似文献
18.
F. Aliotta M. E. Fontanella C. Vasi M. Sacchi G. La Manna V. Turco-Liveri 《Il Nuovo Cimento D》1994,16(7):771-781
Summary The statical and dynamical properties of lecithin/H2O/cyclohexane cylindrical reverse micelles are investigated as a function of lecithin volume fraction, ϕ, and temperature
at fixed water/lecithin ratio,w
0. The viscosity data are well fitted by the Cates model when the breathing mode of micelles is taken into consideration, overlapping
with the breaking and reforming mechanisms. We present some results from Brillouin-scattering experiment, performed across
the sol-gel transition. In order to explain the experimentally observed ϕ-dependence of the hyperacoustic parameters, a mechanical
model was developed from which the ϕ-dependence of the micelle size distribution was obtained. From a comparison with the
viscosity data the entanglement length was estimated. Furthermore some new results from an incoherent quasi-elastic neutron
scattering experiment are presented. The whole body of the experimental results suggests for a sol-gel transition triggered
by topologic phenomena. When the lecithin volume fraction increases, the kinetic equilibrium between the breaking and reforming
mechanisms of the micelles shifts the mean micelle length towards higher values and the entanglement of the micelles becomes
highly favourable. The obtained results are discussed and compared with other findings in literature.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
19.
I. Gatare J. Buesa H. Thienpont K. Panajotov M. Sciamanna 《Optical and Quantum Electronics》2006,38(4-6):429-443
Bistability as well as dynamics associated to polarization switching in a vertical-cavity surface-emitting laser (VCSEL) submitted
to orthogonal optical injection from an external master laser are investigated. Intensity-polarization switching bistability
is studied by increasing and decreasing the intensity of the injected beam and for a fixed frequency detuning, i.e. the frequency
offset between master and the free running VCSEL. Depending on the frequency detuning, bistable switching is experimentally
found to occur with or without injection locking of the fundamental mode to the master laser frequency. For large positive
detuning, injection locking of the first-order transverse mode with a strong depression of the fundamental mode has been observed.
The case of frequency – polarization switching bistability, i.e. when the frequency detuning is first decreased and then increased
for a fixed injected power, has also been theoretically analyzed. Qualitative comparison with previous experimental work is
presented for the dependence of the width of the bistable switching region on the injection strength level. Finally we show
an experimental result of complicated dynamics including period doubling route to chaos that accompany polarization switching
and which motivates future theoretical investigations. 相似文献
20.
1-(4-Aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties
of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy,
circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes
bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal
complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant
activity and be better than standard antioxidants like vitamin C and mannitol.
Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10-5 M, [DNA]=(0-1) ×10-5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(εa – εf) versus [DNA] for the titration of DNA with the complex. 相似文献