共查询到20条相似文献,搜索用时 0 毫秒
1.
Xionggui Tang Jinkun Liao Rongguo Lu Heping Li Xiaoxia Zhang Lin Zhang Yongzhi Liu 《Optics Communications》2011,284(9):2298-2302
The novel optical coding scheme for all-optical analog-to-digital conversion has been proposed, in which asymmetrical Y-branch waveguide structures have been introduced to achieve the desired optical power splitting. The optical performance has been simulated by using finite-difference beam propagation method (FD-BPM), which shows that the designed component exhibits good coding performance. Experimentally, the optical coding component has been fabricated and measured. The optical power contrast between bit code 1 and 0 at output port is more than 37 dB, and measured imbalance of output power is less than 1.5 dB for bit code 1. 相似文献
2.
We present an all-optical WDM-to-TDM conversion scheme with simultaneous all-optical synchronization that can be utilized in switching nodes of very high-speed WDM/OTDM hybrid communication systems. The scheme, which utilizes a nonlinear optical loop mirror in conjunction with a synchronously modelocked semiconductor laser, is experimentally demonstrated by WDM-to-TDM conversion of two optical channels in a switching node. The optical time division multiplexed output has a potential total throughput of ≈40 Gb/s. This all-optical scheme removes limitations of restricted bandwidth of electronics at switching nodes and also has advantages over existing optical time division multiplexing schemes. 相似文献
3.
In this letter, we propose an all-optical parallel scheme for the exclusive-or (XOR) logic processing, in which the bright and dark pixels of an image source are adopted to represent the binary data. Two orthogonally polarized coherent light beams are overlapped using a 50/50 beam splitter, and are then checked using a polarization analyzer. The distribution of light intensity of final output image is the result of the XOR logic operation on the input pixels. 相似文献
4.
Nonlinear optical gain modulation in an InGaAsP/InP bulk reflective semiconductor optical amplifier (RSOA) is studied. The differences of the optical properties between RSOAs and conventional SOAs are initially investigated. All-optical wavelength conversion based on nonlinear gain modulation in RSOAs is demonstrated at a bit rate of 2.488 Gbit/s. It is shown that a bit-error-rate of <10−9 can be achieved and an extinction ratio of >9 dB can be obtained at a bit rate of 2.488 Gbit/s with a 231-1 non-return-to-zero (NRZ) pseudorandom bit sequence (PRBS). In comparison with conventional SOAs, wavelength conversion by RSOAs shows much improved performances in high-speed all-optical wavelength conversions. 相似文献
5.
An approach to all-optical bipolar direct-sequence ultrawideband (UWB) encoding for multiple access communications is proposed and demonstrated. The bipolar coding is performed based on electro-optic phase modulation and phase modulation to intensity modulation (PM-IM) conversion in a fiber Bragg grating (FBG) array that serves as a multichannel frequency discriminator. The chip number and the chip period of the code are determined by the number of FBGs and their physical separation. By locating the optical carriers that carry a Gaussian pulse at the left or right slopes of the FBG reflection spectra, bipolar direct-sequence UWB codes are generated. A bipolar UWB coding system with a code length of 4 is experimentally demonstrated. 相似文献
6.
An all-optical packet filtering module for WDM broadcast-and-select star networks is introduced. At each time instant, only one packet per wavelength is allowed to pass to the star coupler. Therefore, collisions are avoided and the network performance is improved. The proposed module is based on the use of optical logic circuits for controlling the passing of the transmitted packets to the star coupler, without the need of optical to electronic translation or electronic processing of the network feedback information. In this way, the processing time is drastically reduced, while the need for slowly tunable optical filters is eliminated. Furthermore, due to the all-optical nature of the network hub, the reliability of the system is improved. 相似文献
7.
8.
A novel polarization monitoring scheme for polarization division multiplexed (PDM) systems is proposed. By using a tag light transmitted in different but close wavelength to the data signal as the feedback control, the scheme can demultiplex automatically two orthogonal polarizations in PDM systems. The effectiveness of the scheme is demonstrated experimentally in a 2×10-Gb/s on-off-keying (OOK) PDM transmission system. 相似文献
9.
Chinmoy Taraphdar 《Optik》2011,122(1):33-36
In this paper, for the first time to our knowledge, we propose and describe a novel design of single circuit capable of generating all the possible 27 logic functions for single input ternary (3-valued) logic system in all-optical domain. Here the different logical states have been represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch plays a significant role as ultra-fast all-optical switching device. Proposed all-optical circuit is numerically investigated and simulated. 相似文献
10.
J.D. Marconi S. Arismar Cerqueira Jr. N. Sherwood-Droz H.E. Hernandez-Figueroa A.L. Gaeta 《Optics Communications》2009,282(5):849-192
The performance of microphotonic-silicon devices in a geographically-distributed optical fiber network is experimentally investigated. Two different devices are tested: an optical filter based on a silicon ring resonator and an all-optical wavelength converter based on four-wave mixing in a dispersion-tailored highly nonlinear silicon waveguide. The evaluation of the devices is performed by means of eye diagrams and measurements of the bit error rate. 相似文献
11.
12.
Strip silicon waveguide for code synchronization in all-optical analog-to-digital conversion based on a lumped time-delay compensation scheme 下载免费PDF全文
An all-optical analog-to-digital converter(ADC) based on the nonlinear effect in a silicon waveguide is a promising candidate for overcoming the limitation of electronic devices and is suitable for photonic integration. In this paper, a lumped time-delay compensation scheme with 2-bit quantization resolution is proposed. A strip silicon waveguide is designed and used to compensate for the entire time-delays of the optical pulses after a soliton self-frequency shift(SSFS) module within a wavelength range of 1550 nm–1580 nm. A dispersion coefficient as high as-19800 ps/(km·nm) with ±0.5 ps/(km·nm)variation is predicted for the strip waveguide. The simulation results show that the maximum supportable sampling rate(MSSR) is 50.45 GSa/s with full width at half maximum(FWHM) variation less than 2.52 ps, along with the 2-bit effectivenumber-of-bit and Gray code output. 相似文献
13.
14.
A novel scheme of time-stacked optical code label based on optical code division multiple (OCDM) technique for optical packet switching network is proposed, in which two-dimensional wavelength-time OCDM code is used as the optical label. Packet loss rate and system characteristic based on the proposed scheme are studied. Results show that less packet loss rate of proposed scheme can be achieved as compared with that of one-dimension time-stacked optical code label system. 相似文献
15.
In this work, we present two new low-complexity network decoding strategies for cooperative network coding in a multiple-access relay channel scenario. For these two strategies, Selection and Soft Combining and Majority Vote Network Decoding, along with the optimal joint network decoding, we derive expressions for bit error probability performance as a function of the signal-to-noise ratio (SNR) of the different Rayleigh fading links, and show the tightness of the derived bounds through simulation results. The two proposed schemes provide a similar bit error probability (BEP) performance compared to the optimal scheme, while having significantly lower complexity. Further, we study the effect of user pairing on the error performance by considering different SNRs on the user and relay links towards the destination. It is also shown that the error performance of the different schemes follows the same trend for a given user pairing strategy. 相似文献
16.
The overall burst loss probability is the primary metric of interest in an optical burst switching network with sparse wavelength conversion capabilities (SWCC-OBS). With the overall burst loss probability as the optimization objective, one has to solve an integer nonlinear programming (INLP) problem. In order to overcome the computational difficulties we propose a fictitious play method to approximately solve the INLP. Consequently, a randomized routing strategy can be achieved. The simulation results show that the proposed strategy can give a near-optimal route that avoids the conflict of burst data effectively and decreases the overall burst loss probability. At the same time it also performs well in balancing loads throughout the whole network under different kinds of burst traffic pattern. 相似文献
17.
In this paper, we investigate the employment of a ternary line coding technique based on Ungerboeck's trellis-coded method in asynchronous optical CDMA systems. The ternary coding we use is predicated upon the equal-weight orthogonal (EWO) scheme. Each user transmits two mutually orthogonal signature sequences to represent “+1” and “−1”, respectively, and nothing is transmitted for “0”. The receiver employs a maximum-likelihood soft-decoder to select the path with minimum Euclidean distance as the preferred path. This trellis ternary coding scheme applies set partitioning with partially overlapping subsets to increase the free Euclidean distance, which considerably improves system performance. Furthermore, due to line coding technique, such scheme comprises sufficient clock information, and thus benefits for baseband timing extraction (i.e. clock recovery). Numerical results reveal that the proposed trellis ternary coding scheme can significantly reduce the error floor and allow more active users to be accommodated in the network. 相似文献
18.
The blocking probability in wavelength-routed all optical networks is very important measure of performance of the network, which can be affected by many factors such as network topology, traffic load, number of links, algorithms employed and whether wavelength conversion is available or not. In this paper, we have proposed a mathematical model to reduce the blocking probability of the WDM optical network for wavelength-convertible networks. The model can be used to evaluate the blocking performance of any network topology also it can be useful to improve its blocking performance of the given network topology. The blocking probability variation of the network for a particular load (per link) has been studied based on the load variation and total number of wavelengths used in the network. This model gives good results for high load (per link). 相似文献
19.
Zhiyao Zhang Xiaojun Zhou Rui Liang Zujun Qin Yong Liu 《Optics Communications》2009,282(15):3163-3167
In this paper, a novel all-optical bit-error indicating scheme is numerically studied. The bit-error indicating function is achieved by two all-optical processing stages. Firstly, the amplified original bit stream propagates through a high-nonlinear fiber and experiences self-phase modulation which causes intensity-dependent spectrum broadening and split. And then, the bit stream output from the high-nonlinear fiber is filtered by a band-pass filter with the same central wavelength as the original bit stream to generate an error bit indicating signal. The error bit indicating signal, in which only the “Error” bits have the highest peak power, is synchronous with the delayed original bit stream. Therefore, the position of the “Error” bits in the original bit stream can be identified by setting only one judge threshold in the error bit indicating signal. The scheme is demonstrated for an 80 Gb/s bit stream with return-to-zero format by simulation. The results show that the scheme can be used for the all-optical bit-error indicating of the super high bit-rate systems using the return-to-zero format which is favored in the optical time division multiplexing transmission systems. 相似文献
20.
Optics is a potential candidate in information, data, and image processing. In all-optical data and information processing, optics has been used as information carrying signal because of its inherent advantages of parallelism. Several optical methods are proposed in support of the above processing. In many algebraic,arithmetic, and image processing schemes fundamental logic and memory operations are conducted exploring all-optical devices. In this communication we report an all-optical matrix multiplication operation with non-linear material based switching circuit. 相似文献