|
A Two-Photon Femtosecond Laser System for Three-Dimensional Microfabrication and Data Storage
JIANG Zhong-Wei, ZHOU Yong-Jun, YUAN Da-Jun, HUANG Wen-Hao, XIA An-Dong,
Chin. Phys. Lett. 2003, 20 (12):
2126-2129
.
Utilizing the well-focused femtosecond laser with extreme high pulse intensity, we built a two-photon microfabrication and data storage system, which was introduced through several functional parts. Based on this homemade system, several three-dimensional microstructures were fabricated by two-photon polymerization, and three-dimensional data storage of six-layers was achieved by two-photon excitation with a photochromic material.
|
|
Cosmic Strings and Quintessence
DUAN Yi-Shi, REN Ji-Rong, YANG Jie
Chin. Phys. Lett. 2003, 20 (12):
2133-2136
.
Using torsion two-form we present a new Lorentz gauge invariant U(1) topological field theory in Riemann-Cartan space-time manifold U4. By virtue of the decomposition theory of U(1) gauge potential and the Ф-mapping topological current theory, it is proven that the U(1) complex scalar field Ф can be looked upon as the order parameter field in our Universe, and a set of zero points of Ф(x) create the cosmic strings as the space-time defects in the early Universe. In the standard cosmology, this complex scalar order parameter field possesses negative pressure, provides an accelerating expansion of Universe, and be able to explain the inflation in the early Universe. Therefore this complex scalar field is not only the order parameter field created the cosmic strings in the early universe, but also reasonably behaves as the quintessence, the dark energy.
|
|
Statistical Significance of Non-Reproducibility of Cross Sections in Dissipative Reactions
WANG Qi, DONG Yu-Chuan, LI Song-Lin, TIAN Wen-Dong, LI Zhi-Chang, LU Xiu-Qin, ZHAO Kui, FU Chang-Bo, LIU Jian-Cheng, JIANG Hua, HU Gui-Qing
Chin. Phys. Lett. 2003, 20 (12):
2144-2147
.
Two independent excitation function measurements have been performed in the reaction system of 19F+93Nb using two target foils of the same nominal thickness. We measured the dissipative reaction products at incident energies of 102 through 108 MeV with a step of 250 keV. The variance of energy autocorrelation functions of the reaction products was found to be three times of that originated from the randomized counting rates. By analysing the probability distributions of the deviations in the measured cross sections, we found that about 20% of all the deviations exceeds three standard deviations. This indicates that the non-reproducibility of the cross sections in the two independent measurements is of a statistical significance but not originated from randomized fluctuation of counting rates.
|
|
Femtosecond Dynamics of Energy Transfer in Native B800-B850
and B800-Released LH2 Complexes of Rhodobacter Sphaeroides
LIU Wei-Min, ZHU Rong-Yi, XIA Chen-An, LIU Yuan, XU Chun-He, QIAN Shi-Xiong
Chin. Phys. Lett. 2003, 20 (12):
2148-2151
.
Two kinds of antenna complexes LH2 of Rhodobacter sphaeroides, wild type RS601 and the removal of B800 pigments (B800 released), were used in our experiment. These two LH2 complexes show quite different behaviour in absorption and femtosecond dynamics. By using the femtosecond pump-probe technique, the energy transfer processes occurred in two complexes were studied. Because of removing the B800 pigment from the LH2 in B800-released LH2 complex, the energy transfer between the B800 to B850 pigment was completely eliminated, while the pure internal energy transfer within the exciton states of B850 pigment could be carefully investigated. The results show that, at B800 absorption band, B800-released LH2 obviously shows a dominated transient absorption different from the photobleaching observed in RS601; while at the B850 band, these two complexes show similar photobleaching behaviour.
|
|
Optical Oscillator Strengths of Hydrogen Chloride in the
Energy Region of 5.5-20eV
LI Wen-Bin, ZHU Lin-Fan, LIU Xiao-Jing, YUAN Zhen-Sheng, SUN Jian-Min, CHENG Hua-Dong, Yasuhiro Sakai, XU Ke-Zun
Chin. Phys. Lett. 2003, 20 (12):
2152-2154
.
Absolute optical oscillator strength density (OOSD) spectrum of HCl in the valence shell energy region of 5.5-20 eV has been determined by the high resolution fast electron energy loss spectrometer (EELS). The optical oscillator strengths for the broad A1 + 13Σ+ dissociation peak and the discrete transitions of b3(v' = 0), C1(v'= 0,1,2) and M1(v'= 0) are reported.
|
|
A Novel Optical Filter for Removing Bright-Background Using an
Enhanced Bacteriorhodopsin Thin Film
ZHANG Chun-Ping, GU Li-Qun, CHEN Gui-Ying, GUO Zong-Xia, FU Guang-Hua, ZHANG Guang-Yin, ZHANG Tian-Hao, LI Yu-Dong, Q. Wang SONG
Chin. Phys. Lett. 2003, 20 (12):
2161-2164
.
We found that the bacteriorhodopsin (bR) film has a special property of complementary suppression modulated transmission (CSMT). The yellow and the blue beams can be suppressed mutually when both the beams illuminate the bR film simultaneously. When the blue beam carrying an image with a bright-background noise illuminates on the bR film and then a yellow beam with uniform intensity distribution illuminates the same area, the bright-background can be removed due to the CSMT. In our demonstration, the pattern model is letters “VLSI”with ground noise of small words and the ground noise is removed from the pattern by the new optical filter.
|
|
Ultrasound-Modulated Optical Tomography in Reflective and Coaxial Configuration
FU Hong-Bo, XING Da, ZENG Ya-Guang, WANG Yi, CHEN Qun
Chin. Phys. Lett. 2003, 20 (12):
2165-2168
.
Ultrasound-modulated optical tomography affords a very promising noninvasive imaging method for biomedical diagnosis. With this technique, an ultrasound beam is focused into a scattering medium to provide an accurate localization and, simultaneously, a modulation of laser light inside the medium. Based on the high-sensitivity detection technique, we have developed a unique reflective configuration, which was more convenient and practical than other existing configurations. Furthermore, the configuration also introduced a new scheme to improve the spatial resolution in the imaging. A phantom was imaged to validate the fesibility of the proposed configuration.
|
|
Yb3+-Doped Double-Clad Fibre Laser Based on Fibre Bragg Grating
FAN Wan-De, FU Sheng-Gui, ZHANG Qiang, NING Ding, LI Li-Jun, WANG Zhi, YUAN Shu-Zhong, DONG Xiao-Yi
Chin. Phys. Lett. 2003, 20 (12):
2169-2171
.
A novel Yb3+-doped double-clad fibre laser based on a double-clad fibre Bragg grating is presented. The fibre Bragg grating, as the output mirror, has been formed in Yb3+-doped double-clad fibre with the phase-mask method. When the input pump power is 2.8 W, the maximum laser output power is 570 mW, with < 0.2 nm in line-width at the wavelength of 1.058 μm, over 40dB signal-to-noise ratio and 24% slope efficiency.
|
|
Green-Light Static Rewritable Optical Storage Properties of a Novel CuTCNQ Derivative Thin Film
HUANG Wu-Qiao, WU Yi-Qun, GU Dong-Hong, GAN Fu-Xi
Chin. Phys. Lett. 2003, 20 (12):
2178-2181
.
A novel charge-transfer complex film: copper-(n-propyl ester 7,7,8,8- tetracyanoquinodimethane-2,5-ylene-(3-propionic acid)) (Cu-TCNQ(C2H4COOC3H7)2) was prepared by spin-coating. Absorption spectra, green-light (514.5 nm) static rewritable optical recording properties and rewritable mechanism of this film were studied. The results show that there are two strong absorption peaks at 388 nm and 675 nm, which can be assigned to electronic transitions in anion radical TCNQ(C2H4COOC3H7)-2. Green-light optical storage experimental results of this film were as follows: write-in power was 9 mW, pulse duration was 80 ns; erasing power was 4 mW, pulse duration was 500 ns; the reflectivity contrast C ≥15%; number of write-erase cycle N ≥ 100. It is found that the realization of rewritable optical storage of the Cu-TCNQ (C2H4COOC3H7)2 film is related to the reversible changes of the optical properties, which is caused by the reversible charge transfer between copper and n-propyl ester 7,7,8,8- tetracyanoquinodimethane-2,5-ylene-(3-propionic acid) in the complex through inducement of laser irradiation.
|
|
Short-Time Resistively-Shunted Junction Dynamic Study on Two-Dimensional Fully Frustrated XY Model
YOU Yu, LUO Meng-Bo, YING He-Ping, CHEN Qing-Hu
Chin. Phys. Lett. 2003, 20 (12):
2222-2225
.
Short-time dynamic behaviour of two-dimensional fully frustrated XY model near the Ising-like phase-transition temperature is studied with resistively shunted junction dynamics. The transition temperature Tc and the dynamic and static critical exponents z, 2β/v, and v are estimated under both a periodic boundary condition (PBC) and a fluctuating twist boundary condition (FTBC) using the short-time dynamic scaling analysis. The results show that Tc, 2β/v, and v are almost independent of the boundary conditions, whereas z depends on the boundary condition. The value of z = 2.18(5) of the PBC is roughly equal to that of the FFXY model with Monte Carlo dynamics under the PBC, while z = 2.05(4) of the FTBC is in agreement with that of the Coulomb gas model.
|
|
Spectroscopy and Optical Properties of Novel Metal(II)-Azo Complex Films in Blue-Violet Light Region
HUANG Fu-Xin, WU Yi-Qun, GU Dong-Hong, GAN Fu-Xi
Chin. Phys. Lett. 2003, 20 (12):
2259-2261
.
A novel azo derivative, α-(2-azoxyisoxazole)-β-diketone derivative (ADD), and its copper (II) and nickel (II) complex (CuADD and NiADD) films have been prepared respectively by spin-coated method. The absorption spectra of the films on a K9 glass substrate in the 300-800 nm wavelength region have been measured. The optical constants (complex refractive index N = n+ik) and thickness of the complex films on a single-crystal silicon substrate in the 300-600 nm wavelength region have been investigated on an improved rotating analyzer-polarizer (RAP) type of scanning ellipsometer, and the dielectric constants ε (ε = ε1 + iε2), absorption coefficients α as well as reflectance R of the films were calculated. It is found that the absorption maxima of the ADD, CuADD and NiADD films are at 324 nm, 372 nm and 385 nm, respectively, and small absorption values and steep absorption band edges of the CuADD and NiADD films are observed at the 405 nm side, the CuADD and NiADD films give high n values of 2.08 and 1.98, and low k values of 0.2 and 0.28, respectively, at 405 nm, and their thicknesses in the range of 130-150 nm, the high reflectivity of 58.5% and 45.5% of the CuADD and NiADD films with Ag as a reflective layer were obtained at the film thicknesses of 70 nm and 80 nm respectively. These results show that the novel CuADD and NiADD films seem to be a very promising organic recording material for next generation of high density digital versatile disc-recordable (HD-DVD-R) systems that use a high numerical aperture of 0.85 at 405 nm wavelength.
|
53 articles
|