An urban wireless optical SAC-CDMA network with MQC is proposed and analyzed. Analytical techniques for performance valuation of synchronous random access packet switching in urban wireless CDMA system are presented. Considering the nodal architecture design at higher layers, as well as the characteristics of the physical layer, such as atmospheric scintillation, phase-induced intensity noise and receiver noise, steady-state throughput characteristics using Binomial Arrival Model are obtained. Numerical results indicate that use of multi access coding can provide utilization-delay characteristics superior to that of ALOHA, and the atmospheric scintillation is an important factor affecting the throughput of urban wireless optical CDMA network when the atmospheric turbulence is comparatively strong.
A new unequal-period radial hollow Bragg fiber structure has been optimum designed to improve the guided flux transmit characteristics. The core of this Bragg fiber is composed of air, and the cladding is formed by a set of alternating layers of up-doped and down-doped silica. The number of the cladding medium layers can be reduced greatly, and some simulation results have been obtained. The simplification of the cladding layers is useful for the fabrication of Bragg fiber.
Based on DWDM technology, optical fiber head can be used to realize multi-wavelengths parallel transmission. An integrated optical fiber head has been optimum designed, which can be used in the multi-layers storage system. The pick-up signal intensity distributions have been simulated for the multi-layers parallel storage system.
All factors of Dense Wavelength Division Multiplexed (DWDM) Wireless Optical Networks relate with one another. Among them, signaling is based on the premise of getting high efficiency of optical bandwidth utilizing, and also with ultra low latency and the lowest rate of data to be dropped. Networks running under the direction of Preliminary Survey with Amending Algorithm (PSAA) may get high bandwidth utilizing efficiency with high Quality of Service (QoS). Our proposed architecture of Area Coverage Technology (ACT) is formed from Substantive Wavelength Channels Distributor (SWCD) allowing cooperation with Distributed Controller (DC). Finally, some excellent network performance is revealed by simulation and experiment.
This paper mainly shows that to utilize the characteristics of wireless optical transmission, Space-Frequency(SF) addressing mode mating with Optical Weaving(OW) topology and route planning by employing Hybrid Methods (HM) make wireless optical network provide unique services with high Quality of Service(QoS) which can not be offered by the other means of communication
Free Space Optical technology (FSO) is transparent to communication protocols, the most efficient way to utilize it is wireless optical network. Founded on unique characteristics of carriers, the proposed network system disposes every link fitting-in bit-rate with appropriate frame, then coordinate the topology, address, route technology with management technology as well as message technology, so it has the high communication capacity with being controlled delay time from every Class of service (CoS). Ultra low packet loss rate and ultra low latency lay the foundation of it serving for different communication modes with high Quality of Service (QoS). All works will be done from the physical layer to the network layer.
The temperature dependence of the amorphous Sm(Tb,Dy)FeCo quaternary alloys films was investigated using the mean-field model in combination with genetic algorithm. It is shown that when the light rare earth element Sm was substituted for the heavy rare earth element Tb or Dy, the compensation temperature (TCOMP) decreases, Curie temperature (TC) remains unchanged and the saturation magnetization (Ms) at room temperature increases. Experimental data show good agreement with the calculated results.
The principle of ellipsometry measurement and the foundation of the ellipsoidal equation were detailedly described, and the genetic algorithm was introduced to the calculation for refractivity and thickness of film, which ameliorates the astringency and the convergent speed. Emphatically discussed the designation of genetic operators according to the computing program flow chart.
In this paper, an experimental research on the effect of the Miniature Stirling cooler on the noise of a photo-voltaic QD has been fulfilled. Based on strictly implements, the noise power spectrum densities of the QD under Stirling cooling have been measured and compared with that of Liquid N2 cooling. The results showed that the Stirling Cooler will cause additional noise to the QD it cooled, but the increasing noise can be reduced if some means are taken.
In this paper we discuss the heterodyne receiving technology at the band of 10.6 micrometers for single and double tubes and compare the two receiving methods. For an acousto-optic modulation receiving system, we have analyzed the collimation alignment and matching technology of signal optical field. The structure and design of the antenna are also analyzed. Furthermore, the frequency stabilization is analyzed for a double-tube heterodyne system. On the condition of seim-all-weather, the outer field experiments have been taken out, and the terminal signal to noise (S/N) ratio is proven to be better than approximately 50 dB for the analogue FM/FM (electric FM/optical FM) and digital FM/FSK (electrical FM/optical frequency shift key) systems. The terminal bit error rate is better than 10-8. It's very important to develop the technology for 10.6 micrometers laser heterodyne detection.
The dynamical behavior of an intracavity modulation (IM) laser system with a feedback device is discussed in this paper. Some of the modulating methods, i.e., intracavity acousto-optic modulation (IAOM), intracavity electro-optic modulation (IEOM), and intracavity magneto- optic modulation (IMOM), etc., are introduced. The chaotic behavior of these laser systems with a feedback device is analyzed.
A 10.6-micron laser heterodyne receiving system with acoustooptic frequency modulation is described. In this system, the first-order diffraction beams are used as the optical signal modulation beam in the transmitting optical terminal, a 77 K-PV-HgCdTe detector is used as heterodyne reception device in the receiving optical teminal, and the Stark cells are used in the transmission and reception terminals in order to stabilize the frequencies of local and signal laser. With the application of frequency shift key digital modulation, the terminal bit error rate is better than 10 exp -8.
The multistable output characteristics of an intracavity acoustooptic modulation (IAOM) laser system with a negative feedback device is analyzed based on the behavior of the acoustooptic modulator. Quantitative results with and without active medium are obtained. The bifurcate and chaotic behavior of the IAOM system is discussed in detail.
A offset frequency lock system is used for I 0. 6jim laser heterodyne frequency tracking. The system uses digital offset-lock servo loop to realize the offset frequency lock of the tracking laser to the reference one. With computer realtime processing the offset frequency stability of 1 O 1 012is got by nieasurement of Allan variance at different sample times. The tracking range is 45MHz(when offset frequency is 32MHz)and the capture range is about 65MHz. The system shows an excellent anti-interference ability and a high stability.
A series of theoretical and experimental studies shows that the 10.6-micron laser frequency stabilization system of double photoelectric circuits with NH2D Stark Cell has good characteristics. In this system, the frequency stability is measured with heterodyne technique, and computer realtime data processing by means of the Allan Variance calculation. The measurement results of long-term and short-term frequency stability are introduced for different sampling time.
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