共查询到20条相似文献,搜索用时 160 毫秒
1.
Azar M.J. Thompson W.B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(2):228-237
The authors consider the Alfven-Arrhenius fall-down process and propose a mechanism whereby the Rosseland electric field (the field needed to maintain quasineutrality) may be responsible for the capture and confinement of large-gyroradius dust particles within a plasma shell stratified along the direction of the magnetic-field lines. For these particles, the effect of the magnetic force is rather weak, and they move with a constant z component of the angular momentum in a one-dimensional equivalent potential (gravitational plus centrifugal). This has a maximum at the equator and a minimum at the `2/3' points, i.e. the points where the field-aligned components of the gravitational and centrifugal forces balance. It is shown that under suitable initial conditions these are points of maximum dust density and minimum plasma density. The plasma-planetisemal transition is therefore expected to take place at the `2/3' points in accordance with the Alfven-Arrhenius mechanism. It is also shown that the fraction of infalling dust particles that can accrete onto the equatorial plane by the Alfven-Arrhenius and Rosseland mechanisms is rather small (~(L / R e)≪1), L being the thickness of the plasma shell, and R e, a characteristic length scale of the field line 相似文献
2.
Self-organization effect in poly(3-hexylthiophene): methanofullerenes solar cells 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper studies the self-organization of the polymer in solar cells based on poly(3-hexylthiophene): [6, 6]-phenyl C61-butyric acid methyl ester by controlling the growth rate of active layer. These blend films are characterized by UV-vis absorption spectroscopy, charge-transport dark J - V curve, x-ray diffraction pattern curve, and atomic force microscopy. The results indicate that slowing down the drying process of the wet films leads to an enhanced selforganization, which causes an increased hole transport. Increased incident light absorption, higher carrier mobility, and balanced carrier transport in the active layer explain the enhancement in the device performance, the power conversion efficiency of 3.43% and fill factor up to 64.6% are achieved under Air Mass 1.5, 100 mW/cm^2. 相似文献
3.
Kousik Mukherjee 《Optik》2011,122(10):891-895
All optical logic gates exploiting polarization independent four wave mixing in semiconductor optical amplifier (SOA), filtering property of ADD/DROP multiplexer (ADM) and non-linearity in reflective semiconductor optical amplifier (RSOA) have been proposed. The logic gates proposed are polarization independent which ensures hardware simplicity and greater speed. The all optical frequency encoded logic gates NOT, OR, NOR, AND, NAND, X-OR, X-NOR are implemented which are very useful in optical computing ad signal processing, cryptography, etc. The logic gates proposed have the advantages that there is no intensity loss dependent problem, and are polarization and temperature insensitive. 相似文献
4.
All optical multivalued logic processors are of paramount importance in optical computing and signal processing. In this article the author proposes a method of developing all-optical quaternary Inversion, NOT and Bitswap logic gates, which are essential parts of quaternary arithmetic and logical processors. Nonlinear switching and add/drop multiplexing (ADM) properties of semiconductor optical amplifier (SOA) are exploited here to develop the frequency encoded quaternary logic gates. 相似文献
5.
利用(1+1)维Snyder-Mitchell模型讨论了由强非局域介质构成的平面介质波导中同频率和同极化的双光束和三光束同向共同传输的相互作用过程,得到了任意斜入射双光束和三光束相互作用的精确解析解.强非局域空间光孤子的相互作用过程是其特殊情况.基于强非局域空间光孤子的相互作用原理, 提出了实现光子开关、光子“同”(XNOR)和“或非”(NOR)逻辑的新理论方案,并讨论这些基本光子信息处理器件的优化设计问题.
关键词:
强非局域非线性介质
空间光孤子的相互作用
光子开关和光子逻辑 相似文献
6.
提出了一种新型的基于高非线性光纤(HNLF)中非线性 偏振旋转(NPR)效应的全光逻辑门实现方案. 将两路非归零码数据信号A和B以及一路直流光同时注入HNLF, 光功率变化导致的非线性双折射在两个偏振分量上引入非线性相对相移, 从而导致光信号的偏振态旋转. 在HNLF输出端, 通过波分解复用器和偏振分束器同时滤出数据信号和直流光的正交偏振态, 从而同时实现多种基础组合逻辑, 并可以在同一段HNLF中实现较为复杂的半加器、半减器逻辑功能. 理论分析了信号光在HNLF中的偏振态演化, 以及利用HNLF中的NPR效应同时实现多种全光逻辑门的原理. 并在实验中得到了10 Gbit/s全光信号"与”、"非”、"或”、"同或”、"异或”、"A· B”、"A·B”、半加器、半减器等逻辑功能, 验证了方案的可行性. 相似文献
7.
8.
We extend the Blonder, Tinkham and Klapwijk (BTK) theory to the study
of the coexistence between ferromagnetism and s-wave
superconductivity in ferromagnet/superconductor (F/S) structures. It
is found that the ferromagnetism and s-wave superconductivity can
coexist near the F/S interface, which is induced by proximity
effects. On the F side, the density of states (DOS) exhibits some
superconducting-like properties, and it displays a damped oscillation
from `0' to `$\piE-mail: hlya7505@yahoo.com.cn /qk/85823A/200710/25696438.html proximity effects, `\pi' state,
Rashba spin--orbit coupling 7210, 7450 3/3/2007 12:00:00 AM We extend the Blonder, Tinkham and Klapwijk (BTK) theory to the study
of the coexistence between ferromagnetism and s-wave
superconductivity in ferromagnet/superconductor (F/S) structures. It
is found that the ferromagnetism and s-wave superconductivity can
coexist near the F/S interface, which is induced by proximity
effects. On the F side, the density of states (DOS) exhibits some
superconducting-like properties, and it displays a damped oscillation
from `0' to `$\pi$' states with increasing either the thickness of F
film or the exchange energy. We also study the influences of the
spin-polarized exchange splitting in the F and the spin-degeneracy by
Rashba spin--orbit coupling (RSOC) in the two-dimensional electron
gas (2DGE) on the proximity effects. It is shown that the case of
Rashba spin-degeneracy is very different from that of the
spin-polarized exchange splitting. http://cpb.iphy.ac.cn/CN/10.1088/1009-1963/16/10/042 https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=108823 2007-10-08 ' states with increasing either the thickness of F
film or the exchange energy. We also study the influences of the
spin-polarized exchange splitting in the F and the spin-degeneracy by
Rashba spin--orbit coupling (RSOC) in the two-dimensional electron
gas (2DGE) on the proximity effects. It is shown that the case of
Rashba spin-degeneracy is very different from that of the
spin-polarized exchange splitting. 相似文献
9.
Universal reconfigurable optical logic with silicon-on-insulator resonant structures 总被引:1,自引:0,他引:1
Two areas of intense current research, optical logic and silicon photonics, can be combined to create optical logic in silicon substrates. We describe a generic (universal) optical logic gate based on silicon components that can be programmed electronically to perform any logical operation on light beams confined in a silicon waveguide under control of the silicon electronics on the same chip. The effect is to create enhanced integration between optics and electronics. 相似文献
10.
Amal K. Ghosh Animesh Bhattacharya Moumita Raul Amitabha Basuray 《Optics & Laser Technology》2012,44(5):1583-1592
Arithmetic logic unit (ALU) is the most important unit in any computing system. Optical computing is becoming popular day-by-day because of its ultrahigh processing speed and huge data handling capability. Obviously for the fast processing we need the optical TALU compatible with the multivalued logic. In this regard we are communicating the trinary arithmetic and logic unit (TALU) in modified trinary number (MTN) system, which is suitable for the optical computation and other applications in multivalued logic system. Here the savart plate and spatial light modulator (SLM) based optoelectronic circuits have been used to exploit the optical tree architecture (OTA) in optical interconnection network. 相似文献
11.
A new design approach for a three-step modified signed-digit (MSD) adder is presented that can be optically implemented using binary logic gates. The proposed scheme depends on encoding each MSD digits into a pair of binary digits using a two-state and multi-position encoding scheme. The proposed design algorithm depends on constructing the addition truth table of binary-coded MSD numbers and then using Karnaugh map to achieve output minimization. The optical binary logic gates are obtained by simply programming the decoding masks of a shadow-casting-based optical logic gate system. The proposed scheme results in a simple, compact, and efficient optical binary gate-based parallel addition system. 相似文献
12.
All optical logic gates are the most important building blocks for conducting all optical digital and analog signal processing and computing. It has several uses in the high speed communication system. In last few years various non-linear properties of semiconductor optical amplifier have been utilized for realization of all optical logic gates exploiting different type's optical modulations. In such connection optical phase encoding technique drew more attention in last few years as it shows higher receiver sensitivity and extended tolerance limit in long-haul fiber transmission systems. In this communication the authors have proposed an alternative approach for conducting all optical logic gates with phase encoded inputs by the exploitation of the four wave mixing (FWM) property in semiconductor optical amplifier (SOA). 相似文献
13.
Daisuke Ishikawa Atsushi Okamoto Satoshi Honma Terumasa Ito Kohei Shimayabu Kunihiro Sato 《Optical Review》2007,14(4):246-251
In this paper, we propose all-optical multifunctional logic gates for image information using photorefractive (PR) two-wave
mixing. The optical setup is simply configured compared with the other all-optical logic gates for image information. The
XOR-, OR-, and AND-operation are all-optically performed in the same optical setup through the transitional response of the
PR medium. One can switch these logic operations simply by means of the on-off control of the signal and the pump beam illumination.
We analyze the spatial distribution of beam intensity in these logic gates using a finite-difference beam propagation method
(FD-BPM) and the crosstalk between adjoining pixels is examined from the result. We also experimentally verify that the XOR-,
OR-, and AND-gates are realized in the same optical setup. 相似文献
14.
15.
In this paper a novel and simple structure of a high speed optical logic gate based on bulk semiconductor optical amplifier (SOA) is presented. The gain dynamic and phase response of bulk SOA using rate equations including the dynamics of carrier heating (CH) and spectral-hole burning (SHB) is investigated numerically. The operation of NOR gate is analyzed by using the presented numerical method, and a NOR gate that can operate up to 1 Tbps is designed. By using the proposed structure, high speed logic gates based on bulk SOA can be realized. 相似文献
16.
Based on the weakly coupled-mode theory, the coupled-mode equations of the spatial multiwaveguide system are presented in general. The intensity distribution in each waveguide is determined by numerical method. Optical logic devices based on spatial multiwaveguide system are proposed. The analysis results show that the spatial multiwaveguide system permits different Boolean logic states obtained by phase modulation.. Applications of the logic devices include optical calculation, optical interconnection, and spatial optical signal processing. 相似文献
17.
In binary logic the information is represented by two distinct states only (0 and 1 state). The major disadvantage of the binary or Boolean logic operation is due to its limitation of large information handling capacity. It is established that tristate operations can be accommodated with optics in data processing, as this type of operation can enhance the operation speed very much as well as information capacity. Here in this communication the authors propose a new concept to implement all-optical different logic gates with tristate mechanism using frequency-encoding principle. For this purpose, co-propagating beams having different frequencies in C-band have used for generating cascaded sum and difference frequency, exploiting the nonlinear response character of periodically poled LiNbO3 waveguide (PPLN). The highly reflecting property of optical add and drop multiplexer (ADM) and high wavelength conversion property of reflecting semiconductor optical amplifiers (RSOA) have been exploited here to implement the desired AND, NAND,OR and NOR logic operations with tristate. As NAND and NOR are the universal logic operation, so any other member of this logic family may be implemented with these. 相似文献
18.
The design and performance of two optical latches, the Set-Reset (SR) latch and D-Flip-Flop has been studied. These latches are the building blocks of large optical processors. The latches are built using two optical logic operations NAND and NOT. Both NAND and NOT operations are realized by using Mach-Zhender interferometer (MZI) utilizing semiconductor optical amplifier with quantum dot active region (QD-SOA). Nonlinear dynamics including carrier heating and spectral hole-burning in the QD-SOA are taken into account together with the rate equations in order to realize the all-optical logic operations. Results show that this scheme can realize the functions of Set-Reset latch and D-Flip-Flop at high speeds (∼250 Gb/s). The dependence of the output quality (Q factor) on QD-SOA parameters is also discussed. 相似文献
19.
All-optical NOT and XOR logic operation at 2.5 Gb/s based on semiconductor optical amplifier loop mirror 下载免费PDF全文
All-optical XOR and NOT logic operations based on semiconductor optical amplifier loop mirror (SLALOM) aresimultaneously demonstrated theoretically and experimentally. Based on a segmented semiconductor optical amplifier model, the all-optical logic operation process is simulated theoretically. In an experimental study, 2.5 Gb/s all-optical XOR operation was achieved in the output port of SLALOM, while all-optical NOT operation was achieved in the input port through a circulator at the same time. 相似文献
20.
To implement all-optical burst-mode clock extraction we adopt a modified terahertz optical asymmetric demultiplexer (MTOAD). The transmittance and reflectance of the MTOAD depend on the input intensity. For the MTOAD, two levels of pulse intensity can be chosen in such a way that while the pulses with similar intensity are reflected for both strong and weak pulses, only the strong pulse transmits. The device is useful, for example, for bit-level clock extraction from a packet, where strong and weak intensity pulses are assigned to ‘1' and ‘0', respectively. When the input optical signal power is fixed to −1.6 dBm and the intensity ratio between ‘1' and ‘0' is varied in the range of 0.2–0.5, the extinction ratio (ER) at the transmitted port is more than 10 dB and a clock amplitude jitter (CAJ) of the bit-level clock at the reflected port is less than 14%. Inversely, when the input power is varied in the range of −6–−1 dBm with fixed intensity ratio of 0.3, more than 11 dB of ER and less than 15% of CAJ are obtained. 相似文献