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1.
We present the results of research on continuous tuning of a neodymium laser radiation frequency in the UV and vacuum ranges.
We obtained generation of the total frequency of the waves of the second harmonic and of parametric light generator radiation
in the UV region (338–366 nm). We investigate the optimum conditions for tuning UV radiation in the 113.5–117.0 nm range in
the process of generation of the third harmonic in xenon and its mixtures with other gases. In the vacuum UV range investigated,
an efficiency of generation of the third harmonic of ∼5·10−4 and a tuning range above 2600 cm−1 are realized.
Scientific Industrial Association “Akadempribor”, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent, 700143, Uzbekistan.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 528–535, July–August, 1997. 相似文献
2.
The generation of lower (third) and higher harmonics of femtosecond laser radiation in plasmas produced by laser ablation
of different targets with a small atomic number Z (B, Be, Li) has been investigated. The high (10−3) efficiency of third-harmonic generation was observed in plasma produced on the boron surface. Efficient third-harmonic generation
was also observed in beryllium plasma using femtosecond pulses of Ti:sapphire laser radiation (λ = 790 nm) and its second
harmonic (395 nm). We could tune the higher harmonics generation spectrum by tuning the crystal converter when using 395-nm
radiation to be converted. It is shown that, in plasmas formed on targets with small Z, the conversion efficiency and limiting generated harmonic order depend on the delay between the ablation pulse and the pulse
to be converted. 相似文献
3.
A compact setup for generation, frequency stabilization, and precision tuning of UV laser radiation at 313 nm was developed.
The source is based on frequency quintupling of a C-band telecom laser at 1565 nm, amplified in a fiber amplifier. The maximum
output power of the source at 313 nm is 100 mW. An additional feature of the source is the high-power output at the fundamental
and the intermediate second- and third-harmonic wavelengths. The source was tested by demonstration of laser cooling of Be+ ions in an ion-trap apparatus. The output of the source at the third-harmonic wavelength (522 nm) was used for stabilization
of the laser frequency to molecular iodine transitions. Sub-Doppler spectroscopy and frequency measurements of hyperfine transitions
in molecular iodine were carried out in the range relevant for the Be+ laser cooling application. 相似文献
4.
A. K. Chaudhary A. M. Rudra P. Kumbhakar G. C. Bhar 《Journal of Applied Spectroscopy》2007,74(4):571-577
We report a technique for the efficient generation of tunable coherent deep UV radiation and its application in studies of
RDX and TNT at the ppm level on the basis of their absorption characteristics. The obtained experimental absorption data are
compared with conventional spectrophotometric data. The UV radiation in the range 200–260 nm has been generated by the type-I
noncollinear third harmonic of the dye laser radiation (600–700 nm) and also by sum frequency mixing (SFM) of Nd:YAG output
(1064 nm) with the second harmonic of the dye laser in β-barium borate (BBO) crystal. The maximum conversion efficiency of
the generated signal is estimated to be 57.5% at λ = 218.9 nm wavelength. Apart from measurements of the absorbance of RDX
and TNT at different concentrations in their respective solutions, the minimum detection concentrations have also been ascertained.
The estimated minimum detectable concentration of RDX is 8.47·10−9 M, whereas that for TNT is 35.7·10−9 M. The data were obtained using only ∼100 μJ/pulse of laser energy.
Published in Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 516–521, July–August, 2007. 相似文献
5.
N. Muhammad D. Whitehead A. Boor W. Oppenlander Z. Liu L. Li 《Applied Physics A: Materials Science & Processing》2012,106(3):607-617
The demand for micromachining of coronary stents by means of industrial lasers rises quickly for treating coronary artery
diseases, which cause more than one million deaths each year. The most widely used types of laser for stent manufacturing
are Nd:YAG laser systems with a wavelength of 1064 nm with pulse lengths of 10−3–10−2 seconds. Considerable post-processing is required to remove heat-affected zones (HAZ), and to improve surface finishes and
geometry. Using a third harmonic laser radiation of picosecond laser (6×10−12 s pulse duration) in UV range, the capability of the picosecond laser micromachining of nitinol and platinum–iridium alloy
for coronary stent applications are presented. In this study dross-free cut of nitinol and platinum–iridium alloy tubes are
demonstrated and topography analysis of the cut surface is carried out. The HAZ characteristics have been investigated by
means of microscopic examinations and measurement of micro-hardness distribution near the cut zones. 相似文献
6.
K. R. Allakhverdiev M. Ö. Yetis T. K. Baykara S. M. T. Özbek E. Yu. Salaev 《Laser Physics》2011,21(3):598-600
Two methods of preparation of the devices for visualization of pulsed and continuous near-IR (near infrared) are described
and the results of conversion of pulsed and continuous IR (800–1360 nm) laser radiation into the visible range of spectra
(400–680 nm) by using a transparent substrate covered with the particles (including nanoparticles) of effective nonlinear
materials of GaSe
x
S1 − x
(0.2 ≤ x ≤ 0.8) are presented. Converted light can be detected in transmission or reflection geometry as a visible spot corresponding
to the real size of the incident laser beam. Developed device structures can be used for checking if the laser is working
or not, for optical adjustment, for visualization of distribution of laser radiation over the cross of the beam and for investigation
of the content of the laser radiation. Low energy (power density) limit for visualization of the IR laser pulses with 2–3
ps duration for these device structures are: between 4.6–2.1 μJ (3 × 10−4−1 × 10−4 W/cm2) at 1200 nm; between 8.4–2.6 μJ (4.7 × 10−4−1.5 × 10−4 W/cm2) at 1300 nm; between 14.4–8.1 μJ (8.2 × 10−4–4.6 × 10−4 W/cm2) at 1360 nm. Threshold damage density is more than 10 MW/cm2 at λ = 1060 nm, pulse duration τ = 35 ps. The results are compared with commercially existing laser light visualizators. 相似文献
7.
V. N. Bagratashvili N. V. Minaev A. A. Rybaltovsky A. O. Rybaltovsky S. I. Tsypina V. Ya. Panchenko Yu. S. Zavorotny 《Laser Physics》2010,20(1):139-143
The fabrication of photoand thermostable periodic structures from silver nanoparticles in polymer plates (cross-linked oligourethanemethacrylate
impregnated with silver precursors Ag(hfac) and Ag(fod) dissolved in the supercritical carbon dioxide) is studied. The process
is based on the local (depending on the irradiated spot size) photochemical decomposition of the silver precursors in the
polymer matrix that initiates the atomic aggregation and creation of silver nanoparticles with the plasmon resonance in absorption
in the spectral range 420–430 nm. The third-harmonic radiation of a Nd:YAG laser (355 nm) and the Kr+-laser (521 nm) radiation are employed for the recording of periodic structures with submillimeter and micron resolutions.
The photosensitivity of the polymer matrices impregnated with the silver precursors to the UV and visible radiation is discussed. 相似文献
8.
The photoconductivity (PC) spectra and the induced absorption of background radiation in the energy range 10–40 meV are investigated
in weakly compensated B-, Ga-, and As-doped silicon at 4.2 K. It is shown that dips corresponding to the photoionization of
long-lived excited states of B and As are observed in the PC spectra on the D
−(A
+) bands. It is found that the frequency dependence of the PC spectra corresponds to excitation relaxation times of the order
of 10−4 s for the states in the D
− (A
+) bands. It is established that in electric fields E>100 V/cm the PC decreases sharply, while the induced absorption of the background radiation changes very little. This confirms
the conclusion that the excitation of the D
− (A
+) itself makes the main contribution to the PC.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 224–227 (25 August 1997) 相似文献
9.
R. A. Ganeev H. Singhal P. A. Naik J. A. Chakera A. K. Srivastava T. S. Dhami M. P. Joshi P. D. Gupta 《Applied physics. B, Lasers and optics》2010,100(3):581-585
The results of enhanced harmonic generation in fullerene-containing plasma plumes using laser radiation of different wavelengths,
pulse durations, and phase modulation are presented. Odd and even harmonics up to the 29th order of 800 nm radiation have been extended in the case of two-color orthogonal polarization pump of C60-containing plasma plumes. The conversion efficiency for the odd and even harmonics in the vicinity of SPR of the C60-containing plasma (40–70 nm) was estimated to be in the range of 10−4. 相似文献
10.
R. Castro-Beltran G. Ramos-Ortiz C. K. W. Jim J. L. Maldonado M. H?u?ler D. Peralta-Dominguez M. A. Meneses-Nava O. Barbosa-Garcia B. Z. Tang 《Applied physics. B, Lasers and optics》2009,97(2):489-496
The nonlinear optical properties of a hyperbranched polyyne (hb-Polyyne) have been measured at infrared wavelengths by using femtosecond and nanosecond pulsed excitation. This hyperbranched
polyyne exhibited strong and intrinsic (simultaneous) two-photon absorption and upconverted blue fluorescent emission under
femtosecond excitation around 800 nm. The hb-Polyyne in chloroform solution is characterized by a large two-photon absorption cross section of 9068 GM (1GM=10−50 cm4 s) and a fluorescence quantum yield of 0.57. On the other hand, by third-harmonic generation (THG) spectroscopy with nanosecond
excitation, the measured third-order nonlinear susceptibility χ
(3) for solid films of hb-Polyyne ranged from 2.4×10−11 to 6.1×10−11 esu in the spectral range of 1100–1600 nm, with results comparable to the values exhibited by the well-known conjugated polymer
MEH:PPV, but with a much better transparency for visible wavelengths. 相似文献
11.
The emission from the plasma of a contracted longitudinal dc discharge in a He/CF2Cl2 mixture in the wavelength range 130–300 nm is investigated. It is shown that the discharge plasma emits within the range 150–260 nm. The emission consists mainly of the broad bands of Cl2 molecules and single-charged chlorine ions. The pressure and composition of the working mixtures, the discharge current, and the time during which the emitter can operate on a single gas fill are optimized to attain the best characteristics of UV and VUV radiation. The results obtained are of interest for developing a steady-state source of VUV and UV radiation to be applied in microelectronics, photochemistry, and medicine. 相似文献
12.
The submillimeter absorption spectra of pure water vapor and a water vapor + dry air mixture are experimentally studied under
the conditions of illumination of the gas sample by ultraviolet (UV) radiation. The measurements were carried out by a vacuum
echelette spectrometer in the wave number range 21.5–56 cm−1 with spectral resolution 0.4–0.9 cm−1, using a DRT-375 mercury-vapor discharge lamp as the source of UV radiation. In contrast to the results of similar experiments
performed by other researchers, the data presented here demonstrate the absence of a noticeable effect of the UV radiation
on the absorption spectra of the gas samples used.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 41, No. 5, pp. 581–587, May, 1998. 相似文献
13.
The photoluminescence and photoexcitation spectra as well as the luminescence decay kinetics of Er3+ ions in the visible ultraviolet and vacuum ultraviolet (VUV) regions have been studied by the method of low-temperature,
time-resolved VUV-spectroscopy on excitation by synchrotron radiation. In the VUV spectral region of the luminescence of SrF2:1% Er3+, the 146.5-nm band with a time of decay of less than 0.6 nsec was revealed together with the well-known emission band at
164.3 nm (decay constant in the microsecond range). Its possible nature is discussed. The specific features of the formation
of photoexcitation spectra of the f-f and f-d transitions in the Er3+ ion are considered. Competition between the processes of excitation of f-f and d-f luminescence has been revealed. It manifests
itself in the inverse relationship of their photoexcitation spectra in a range of energies of incident photons that are close
to the position of the 4fn−15d configuration levels.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 519–523, July–August, 2005. 相似文献
14.
The results of the studies on the transformation of the frequency of laser radiation in polyimide films doped by C70 are presented. The nonlinear susceptibility (χ(3)) of polyimide 6B films with various concentrations of C70 is studied by third-harmonic generation. At a wavelength of 1064 nm, the value of χ(3)(−3ω; ω, ω, ω) is 9×10−13 esu. The effect of the nonlinear variation in the refractive index of the fullerene-containing films on the phase matching between the pumping and third-harmonic waves is analyzed. The third harmonic of the Nd: YAG laser radiation was generated with the efficiencies 6×10−6 and 10−6 in the films with the C70 concentration of 0.5 and 0.2%, respectively. 相似文献
15.
A. A. Voronkov B. P. Gorshunov V. S. Nozdrin E. S. Zhukova T. Matsuoka K. Tanaka S. Miyasaka S. Tajima M. Dressel 《JETP Letters》2012,94(9):708-713
The spectra of the conductivity and dielectric constant of La1.87Sr0.13CuO4 cuprate have been directly measured in the frequency range of 0.3 to 1.2 THz (10–40 cm−1) and the temperature range of 5 to 300 K in the E | c polarization (the electric field vector of radiation is perpendicular to the copper-oxygen planes). Excitation has been observed
in the superconducting phase, and its nature has been attributed to the transverse optical excitation of the condensate of
Cooper pairs, which appears because Josephson junctions between CuO planes are modulated due to in-plane magnetic and charge
stripes. Additional quasiparticle absorption of unknown origin has been detected at frequencies below ≈15 cm−1 at liquid helium temperatures. 相似文献
16.
V. N. Gorelkin V. G. Grebinnik K. I. Gritsai V. N. Duginov V. A. Zhukov T. N. Mamedov V. G. Ol’shevski V. Yu. Pomyakushin A. V. Stoikov I. L. Chaplygin I. A. Krivosheev B. A. Nikol’skii A. N. Ponomarev 《JETP Letters》1996,63(7):566-571
The residual polarization of negative muons in n-type silicon with impurity density (1.6±0.2) · 1013 cm−3 is investigated as a function of temperature in the range 10–300 K. The measurements are performed in an external magnetic
field of 0.08 T oriented transversely to the spin of the muons. Relaxation of the muon spin and a shift of the precession
frequency are observed at temperatures below 30 K. The relaxation rate at 30 K equals 0.25±0.08 μs−1. The shift of the precession frequency at 20 K equals 7 · 10−3. Both the relaxation rate and the shift of the precession frequency increase as the temperature decreases. At temperatures
below 30 K the relaxation rate is described well by the relation Λ=bT
−q
, where q=2.8±0.2.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 7, 539–543 (10 April 1996) 相似文献
17.
V. V. Slabko A. K. Popov V. F. Lukinykh 《Applied Physics A: Materials Science & Processing》1978,15(2):239-241
Coherent radiation at 89.6 nm has been obtained through third-harmonic conversion of the 268.8 nm pulses in mercury vapors.
Tunability of the fourth-harmonic frequency of the Nd: glass laser radiation to the 6s
1
S
0–8s
1
S
0 double quantum resonance of Hg atoms has been used for the resonant enhancement of the twelfth-harmonic output. Possibility
to phase match the generated radiation and driving polarisation in pure vapors without employing of bufer gas has been demonstrated. 相似文献
18.
It is established that doping of CdS polycrystalline films with alkaline metals (Li, Na, K, Cs) results in an increase of
luminescence intensity by 3–5 times compared with pure films. This increase is accounted for by the placement of alkaline-metal
ions in V
Cd
2−
cation vacancies, which are nonradiative recombination centers in these films. From the dependences of the luminsecence intensity
of the doped films on the synthesis conditions (deposition temperature, concentration of doping impurities, type of doping
metal), the parameters that ensure the maximum luminescence intensity of the films are determined as Tdep ≈ 450°C and CMe = 1·10−5 at %. The luminescence intensity decreases by 1–3% upon exposure of the films to UV light (λmax = 365 nm, I = 1021 quanta·sec·cm−1) for several hours. This is indicative of the stability of these films against UV radiation.
__________
Translated from Zhurnal Prikladnoi Spektroskopii Vol. 74, No. 3, pp. 362–366, May–June, 2007. 相似文献
19.
The ion current of adsorbed water molecules is studied experimentally as a function of the frequency of near-IR radiation
incident on a surface at frequencies in the intrinsic vibrational bands of the water molecule. The ions are produced by nonequilibrium
field surface ionization. The observed band (near one of the combination frequencies) has a width of 100 cm−1 and is shifted relative to the free molecular band by 130 cm−1. Estimates show that the cross section for absorption of the radiation by the adsorbed molecules is 3–4 orders of magnitude
larger than for free molecules, as is typical of surface processes.
Zh. Tekh. Fiz. 69, 123–127 (September 1999) 相似文献
20.
G. A. Komandin O. E. Porodinkov I. E. Spector A. A. Volkov 《Physics of the Solid State》2009,51(10):2045-2050
The reflection and transmission spectra of a MgO single crystal at frequencies of 10–1000 cm−1 in the temperature range 10–300 K have been measured using submillimeter and infrared Fourier spectros-copy. The evolution
of anharmonic absorption with variations in temperature has been investigated in the frequency range below the frequency of
the transverse optical phonon. The parameters of the dispersion model that adequately describes the lattice absorption of
terahertz radiation in single-crystal magnesium oxide have been determined. 相似文献