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ABSTRACT: This paper investigates characteristics of polarization in non-line-of-sight (NLOS) ultraviolet (UV) communication channels based on a vectorized polarization-sensitive model of NLOS multiple-scatter propagation. The degree of polarization has been analyzed from the following factors: elevation angles, beam angle, field-of-view, off-axis angles, and baseline distance, etc. We draw conclusions that will guide the design of polarization multiplexing technology in NLOS UV communication systems. Outdoor experimentation has validated that this technology is useful to improve the data rate.
Applied Optics 12/2012; 51(35):8366-72. · 1.41 Impact Factor
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ABSTRACT: Retroreflective free-space optical (RFSO) communication is a new concept of optical communication; it consists of an optical transceiver and a retromodulator and has advantages such as light weight, small volume, and low power consumption. The power captured by the receiver consists of two parts: retroreflective and scattering. The retroreflective characteristics are obtained using an analytical formula, the scattering characteristics using a Monte Carlo model. Results show that the scattering power plays an important role in a RFSO communication link, especially when the communication range is long or the meteorological range is short. Some rules are also obtained for the sake of system design, which include increasing the range from the transmitter and the receiver properly, increasing the area of the retromodulator, limiting the field of view of the receiver, and limiting the beam divergence of the transmitter.
Journal of the Optical Society of America A 12/2012; 29(12):2608-11. · 1.56 Impact Factor
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ABSTRACT: Using tetraethoxysilane and 3-aminopropyltriethoxysilane as the silica sources, amino-functionalized mesoporous silica thin
films with 3-dimensional cubic structure have been deposited on conducting ITO substrate in the presence of surfactant F127
templates under acid conditions. The acetylcholinesterase (AchE) and cytochrome c (Cyt c) were incorporated into the pores
of mesoporous thin films, and an amperometric biosensor was obtained. After adsorption of AchE and Cyt c, the ordered cubic
structure of mesoporous silica and the bioactivities and electrochemical activities of the immobilized protein and enzyme
molecules were retained. The sensor properties of the biosensor were investigated by using acetylthiocholine iodide as the
substrate and Cyt c as the electron transfer mediator. The inhibition versus the logarithm of concentration was found to be
linear to organophosphorus pesticide dichlorvos over the concentration ranges of 1.0×10−8 mol/L to 1.0×10−3 mol/L with the detection limit of 3.1×10−9 mol/L.
Chinese Science Bulletin 04/2012; 54(17):3023-3028. · 1.32 Impact Factor
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ABSTRACT: The thermal entanglement in (1/2,1) mixed-spin Heisenberg XXZ model is investigated under an external nonuniform magnetic
field. In the uniform magnetic field system, the critical magnetic field B
c and critical temperature T
c are increased by increasing the anisotropic parameter k. The degree of magnetic field b plays an important role in improving the critical temperature and enlarging the region of entanglement in the nonuniform
magnetic field system.
Science in China Series G Physics Mechanics and Astronomy 04/2012; 52(12):1919-1924. · 1.41 Impact Factor
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ABSTRACT: The classical model of non-line-of-sight (NLOS) single-scatter propagation
for coplanar geometries was recently extended to include noncoplanar
geometries; the calculation processes in the extended model are partly based on
the Cartesian coordinate system and are somewhat complicated. A new NLOS
single-scatter propagation model for noncoplanar geometries is presented based
only on the prolate spheroidal coordinate system, which can be considered as
the simplified version of the extended model mentioned above. Similar to the
polarization-extension of the Monte-Carlo-based multiple-scatter model, the new
single-scatter model for noncoplanar geometries is also extended to take
polarization into account; the polarized single-scatter model is validated by
the Monte-Carlo-based polarized model, results show perfect match. The
theoretical feasibility of a 2-polarization UV communication link is validated
based on the polarized single-scatter model.
01/2012;
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ABSTRACT: This paper studies the effects of the obstacle on non-line-of-sight ultraviolet communication links using multiple-scatter model based on a Monte Carlo method. On the condition that transmitter beam and receiver FOV just pass the top of the obstacle, and ranges is fixed, the received energy density is at its maximum. The path loss increases when the transmitter or the receiver is much near to the obstacle, because the nearby common scattering volumes decrease intensively. The optimal received range decreases with the increasing of the distance between transmitter and obstacle. The predictions are validated with experimental measurements. This work can be used for the guidance of UV system design and network technology to apply in complex surroundings, such as mountain, buildings, etc.
Optics Express 10/2011; 19(22):21216-26. · 3.59 Impact Factor
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ABSTRACT: The existing Monte-Carlo-based non-line-of-sight (NLOS) multiple-scatter propagation model is extended to include polarization and also vectorized to improve the simulation speed by about 500 times. This model is validated by the noncoplanar single-scatter model; the results show a perfect match. Numerical examples for various polarization setups are obtained, and results show that the single-scatter and multiple-scatter signals are all polarization dependent. Therefore, NLOS polarized UV communication with a high data rate is achievable--the polarizing information is coded by a time-dependent polarizer, influenced by the atmospheric channel, and decoded according to the distribution characteristics of the scattered signals after the time-independent analyzers.
Journal of the Optical Society of America A 10/2011; 28(10):2082-5. · 1.56 Impact Factor
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ABSTRACT: A propagation model that describes the characteristics of multiscatter radiation in atmosphere is presented. The model is based on the Monte Carlo method; each scattering process is set as an event of probability. LOWTRAN7 is used to calculate the atmospheric coefficients, and Mie theory is used to calculate the scattering characteristics of the particles. It is shown that the multiscatter model matches the single-scatter model perfectly when the scattering count is 1, and the formula for the single-scatter approximation is modified for the non-line-of-sight (NLOS) problem. It is also shown that the duration of the impulse response is about 8 micros, the proportion of single-scatter irradiance is very small, and the average scattering count is 3.85 instead of 1 when the range is close to 1 km (weather conditions, field of view, and elevation angle are given). All these characteristics are presented for what is, to our knowledge, the first time. This model is wavelength-independent; 0.254 microm is chosen as the wavelength of simulation.
Journal of the Optical Society of America A 11/2009; 26(11):2466-9. · 1.56 Impact Factor
