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1.
In this paper an alternative approach for measurement of στ product for 4
F
3/2→4
I
11/2 transition of Nd3+ doped YVO4 crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane-plane resonator
and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable.
The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is
measured by Gaussian fit to the intensity profiles of the pump beam. The value of στ product of Nd:YVO4 crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple
method for direct measurement of στ product of laser crystals. 相似文献
2.
F. Lenhardt M. Nittmann T. Bauer J. Bartschke J. A. L’huillier 《Applied physics. B, Lasers and optics》2009,96(4):803-807
We report on a high-power 888-nm-pumped continuous-wave Nd:YVO4 laser at 1342 nm. An output power of 24 W emitted into a diffraction limited beam with an M
2 parameter better than <1.1 is demonstrated. At an absorbed pump power of 84 W the optical conversion efficiency is 29%. 相似文献
3.
We present a diode-end-pumped Nd:YAG planar waveguide laser operating on neodymium’s quasi-four-level transition at a wavelength
of 946 nm. Two modes of operation are described: a high-power multi-mode monolithic cavity generating 105 for 210 W of incident
pump power with a slope efficiency of ∼54%, and secondly, a high-radiance configuration employing an external stable resonator
producing a maximum output power of 29.2 for 86.5 W of incident pump-power, with a slope efficiency of 33%. The output beam
quality values of the external cavity were M2 of 3.2 by 2.4, leading to a maximum radiance of 0.43 GW cm−2 sr−1. 相似文献
4.
By using the second-order moment of the power density, the beam width, far-field divergence angle and M2 factor of nonparaxial truncated flattened Gaussian (FG) beams are derived analytically. It is shown that the M2 factor of nonparaxial truncated FG beams depends not only on the truncation parameter δ and beam order N, but also on the initial waist-width to wavelength ratio w0/λ. The far-field divergence angle approaches an asymptotic value of θmax=63.435° when the truncation parameter δ → 0. For the special cases of N = 0 and δ → ∞ our results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated FG beams, respectively. 相似文献
5.
G A V Ramanamurthy K Ramachandra Rao Y Rama Krishna P Venkateswarlu K Bhaskara Rao P V Ramana Rao S Venkata Ratnam V Seshagiri Rao G J Nagaraju S Bhuloka Reddy 《Pramana》2001,56(5):697-703
The Measurement of K
β
K
/α
intensity ratios are measured in some 3d shell elements by using a 2 MeV proton beam along with a high resolution Si(Li) detector. The present Measurement of K
β
K
/α
intensity ratios are in good agreement with Scofield modified theoretical values, thus supporting the basic assumptions in
that theory. From the present Measurement of K
β
K
/α
intensity ratios, it is evident that due to chemical effects, the experimental Measurement of K
β
K
/α
intensity ratios will be increased while they will be decreased due to the presence of simultaneous M-shell vacancies which are produced due to proton excitation. 相似文献
6.
B. Q. Yao F. Chen C. T. Wu Q. Wang G. Li C. H. Zhang Y. Z. Wang Y. L. Ju 《Laser Physics》2011,21(4):663-666
Room temperature Tm, Ho:YVO4 microchip laser operated around 2 μm was demonstrated for the first time to our knowledge. At a heat sink temperature of
283 K, a maximum output power of 47 mW was obtained by using a 0.25 mm length crystal at an absorbed pump power of 912 mW,
corresponding to a slope efficiency of 9.1%. Increasing the temperature to 288 K, as much as 16.5 mW 2052.3 nm single-longitudinal-mode
laser was achieved. The M
2 factor was measured to be 1.4. 相似文献
7.
A 2% Tm3+-doped LiYF4(Tm:YLF) slab is double-end-pumped by two laser diode stacks. The pumped volume has a rectangular cross section. The Tm:YLF
laser produced 148 W of continuos-wave output at 1912 nm in a beam with M
x
2≈199 and M
y
2≈1.7 for 554 W of incident pump power. The slope efficiency with respect to the incident pump power was 32.6%, and the optical-to-optical
efficiency was 26.7%. 相似文献
8.
We report on fundamental and intracavity frequency-doubled emission in a miniature Nd:YVO4 (3×3×1 mm) laser. A maximum slope efficiency of ηs=58.6%, with optical efficiency of η0=53.0% at 780 mW pump power was realized in a TEM00 output beam. To obtain the optimum pump-beam focusing conditions we applied a new formalism in which the pump-beam propagation in the active medium was described by its M2 factor. A good agreement between theoretical predictions and experimental results was observed. In second-harmonic regime, obtained by a KTP crystal, 230 mW green power that corresponds to 54% nonlinear conversion efficiency was reached. 相似文献
9.
Y.J. Chen Y.F. Lin J.H. Huang X.H. Gong Z.D. Luo Y.D. Huang 《Optics Communications》2012,285(5):751-754
Efficient eye-safe 1.6 μm monolithic laser was realized in a c-cut, 0.7-mm-thick Er3+:Yb3+:YAl3(BO3)4 microchip end-pumped by a quasi-continuous-wave 970 nm diode laser. At incident pump peak power of 20.4 W, a maximum output peak power of 2.6 W with a slope efficiency of 19% was obtained when the waist radius of pump laser beam was 220 μm. The spectra and profiles of output beam of the Er3+:Yb3+:YAl3(BO3)4 monolithic laser were measured. The influences of the waist radius of pump laser beam on the slope efficiency and threshold of the monolithic laser were also investigated. 相似文献
10.
We report the continuous-wave (CW) operation of a room-temperature a-cut Ho:YAP laser resonantly end-pumped by a diode-pumped Tm:YLF laser at 1.91 μm. A maximum CW output power of 14.6 W at
2118.7 nm for a-oriented Ho:YAP was obtained, corresponding to the slope efficiency of 69.35% and optical-to-optical conversion efficiency
of 63.04% with respect to absorbed pump power. The laser operated at a single mode (TEM00) with the beam quality factor of M
2 ∼ 1.51. 相似文献
11.
12.
We use all-fiber single-mode lasers as seed source, amplifiers and pump laser coupling amplifier has been experimentally investigated, respectively. The maximum output power is 10.4 W, with the slope efficiency of 54.4% when the seed laser power is 1 W, and the slope efficiency is 48.7% when the seed laser power is 2 W. The slope efficiency of this scheme is higher than that of the all-fiber amplifier. This can be explained by the loss of pump power at the splice dots. The wavelength of the fiber amplifier is 1947.6 nm, the same as the seed laser's, with a linewidth of 2 nm. We estimate the beam quality to be M2 = 2.39, clearly indicating nearly diffraction-limited beam propagation. 相似文献
13.
Starting from an analytical macroscopic/phenomenological model yielding the self-bias voltage as a function of the absorbed
radio-frequency (rf) power of an asymmetric capacitively coupled discharge in NF3 this paper studies the dependence of the ion flux onto the powered electrode on the gas pressure. An essential feature of
the model is the assumption that the ions' drift velocity in the sheath near the powered electrode is proportional to E
α, where E=−ΔU (U being the self-bias potential), and α is a coefficient depending on the gas pressure and cross section of elastic ion-neutral
collisions. The model also considers the role of γ-electrons, stochastic heating as well as the contribution of the active
electron current to the global discharge power balance. Numerically solving the model's basic equations one can extract the
magnitude of the ion flux (at three different gas pressures) in a technological etching device (Alcatel GIR 220) by using
easily measurable quantities, notably the self-bias voltage and absorbed rf power. 相似文献
14.
3.8 W of cw blue light generated by intracavity frequency doubling of a 946-nm Nd:YAG laser with LBO 总被引:10,自引:0,他引:10
Y. Chen H. Peng W. Hou Q. Peng A. Geng L. Guo D. Cui Z. Xu 《Applied physics. B, Lasers and optics》2006,83(2):241-243
Efficient cw intracavity frequency doubling of a diode-end-pumped Nd:YAG laser operating on 4
F
3/2→4
I
9/2 transitions at 946 nm has been demonstrated. A symmetrical cavity with two composite laser rods was designed, which divides the pump power between the two composite laser rods, allowing for greater power scalability. A 30-mm-long LiB3O5 (LBO) crystal, cut for critical type I phase matching at 57 °C, was used for the intracavity frequency doubling of the laser. A maximum output power of 3.8 W in the blue spectral range at 473 nm has been achieved at 39 W of pump power. The beam quality M2 value is 2.3 in both horizontal and vertical dimensions. PACS 42.55.Xi; 42.65.Ky 相似文献
15.
Asymptotic approach to the truncated cosh-Gaussian beams 总被引:3,自引:0,他引:3
The propagation behavior and M
2-factor of truncated cosh-Gaussian (ChG) beams are studied by using the asymptotic approach. Detailed numerical results are given to illustrate the dependence of M
2-factor on the beam decentered parameter , truncation fraction p and power fraction f. Our results are self-consistent and reduce to those of Pare and Belanger [Opt. Commun.
123, p. 679 (1996a); Proc. SPIE
2870, p. 104 (1996b)]. The advantage of the approach is shown, and the problems introduced by the hard-aperture diffraction and the approach used are discussed. 相似文献
16.
17.
Precise measurement of magnetic moment of short-lived β-emitting nuclei12B ( I π=1+, T 1/2=20.18 ms)
Zhou Dongmei Zheng Yongnan Du Enpeng Xu Yongjun Zhu Jiazheng Yuan Daqing Wang Zhiqiang Luo Hailong Zuo Yi Ma Ruigang Duan Xiao M. Mihara M. Fukuda K. Matsuta T. Minamisono Zhu Shengyun 《中国科学G辑(英文版)》2004,47(5):531-539
The spin polarized β-emitting nuclei12B (I
π=1+,T
1/2=20.18 ms) were produced by the nuclear reaction11B(d, p)12B and by the selection technique of the incident deuteron energy and the12B recoil angle following the nuclear reaction. The nuclear magnetic moment of the short-lived nuclei12B was measured by β-NMR with the β-NMR and β-NQR setup established for the first time in China. The nuclear magnetic moment
of12B was determined to be μ=0.99993±0.00048 nm org=0.99993±0.00048 after the precise correction of the Knight shift. 相似文献
18.
Comparison of cw laser performance of Nd:KGW, Nd:YAG, Nd:BEL, and Nd:YVO4 under laser diode pumping 总被引:4,自引:0,他引:4
A.A. Demidovich A.P. Shkadarevich M.B. Danailov P. Apai T. Gasmi V.P. Gribkovskii A.N. Kuzmin G.I. Ryabtsev L.E. Batay 《Applied physics. B, Lasers and optics》1998,67(1):11-15
4 crystals under low-power laser diode end-pumping. Output power dependencies on the pump power and the pump wavelength of
these diode-pumped solid state lasers were investigated. The high Nd3+ concentration of the Nd:KGW samples used in our measurements as well as up-conversion and exited-state absorption processes
in Nd:KGW cause the reduced laser output power dependence on the pump wavelength which was experimentally observed. At pump
levels up to 270 mW a slope efficiency of ηsl≈46% was reached for the Nd:KGW laser. Nd:KGW microchip laser operation with a slope efficiency of ηsl≈50% was demonstrated. Thermal lensing in Nd:KGW at pump powers up to 3 W was measured.
Received: 4 August 1997 相似文献
19.
With a view to understanding the role of photo-induced valence changes of impurities in BaTiO3 in the phenomena of photorefraction, EPR experiments were conducted under in situ He-Ne laser illumination. These experiments gave evidence for photoinduced valence change of Fe in BaTiO3 at room temperature. The EPR signal due to trivalent iron was found to reduce in intensity with laser illumination The kinetics
of the valence change has been investigated. Under large fringe width condition, the time constant of the decay is identified
as the dielectric relaxation time τd. The changes in line shape on laser illumination to Dysonian form, appeared most predominantly in mechanically poled crystal
compared to electrically poled single domain crystals. This demonstrated the possible role of domain walls and the defects
there, as source or sinks of charge carriers on photo excitation. It is observed, that there is transient growth of Fe3+, when the laser illumination was put on, before its decay. This was attributed to charge transfer between electrons in oxygen
vacancies and Fe4+. This predicted the growth of a transient grating under depleted pump condition in a two beam coupling experiment. This was
experimentally proved by following the diffracted signal of the reading beam under the depleted pump condition. 相似文献
20.
T. Matsuzaki K. Nagamine K. Ishida S.N. Nakamura N. Kawamura M. Tanase M. Kato K. Kurosawa M. Hashimoto H. Sugai K. Kudo N. Takeda G.H. Eaton 《Hyperfine Interactions》1999,118(1-4):229-234
X-ray and neutron measurements were carried out for muon catalyzed fusion and related phenomena in solid T2. The X-ray originated from the μ- to α sticking in muon catalyzed fusion; t + t + μ
-
→ (μ
-
α) + 2n was measured for the first time, yielding K
α
X-ray intensity of (μα) atom and the intensity ratio of K
β
to K
α
. Utilizing the phenomena of 3He accumulation in solid T2, the X-ray in the μ- transfer process from (tμ) to 3He was detected, providing a formation rate and radiative decay branching-ratio of (t
3Heμ) molecule. From fusion neutron measurements, estimated values were obtained for (ttμ) molecular formation rate as well as sticking probability ωt in ttμ fusion. A possible new insight in t + t fusion reaction process at a low energy limit is also obtained.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献