Analysis on Mode Field Distribution of Waveguide Grating Coupler by the Scalar FDTD

The scalar two--dimensional finite difference time domain (FDTD) method is applied to simulate the mode field distribution of TE0 of the waveguide grating coupler.Computer simulation shows that the same stable mode field distribution pattern is obtained through the different kinds of driving sources. It is found that the optical field mode is determined by waveguide structure and optical wavelength other than the driving source.According to the mode field distribution, the optimum coupling efficiency can be predicted.Compared with another numerical methods, the CPU- time and memory elements of computer used by FDTD are much less.     

Design of Polarization-independent Wavelength-interleave Coupler in Fluorinated Polyimide Waveguide

Based on the measurement of dispersion characteristic and birefractive index of the fluorinated polyimide film,a statistical optimum design method is proposed and used to realize the design of 32-and 36-wavelengths optical waveguide wavelength-interleave coupler (i,e.,interleaver) with the optimization of polarization fluctuation and wavelength interval of 0.8nm at 1550nm. The largest cross coupling ratios of the two interleavers are respectively less than 1.8% and 3.5%, while the least through coupling ratios are respectively greater than 98. 2% and 96. 5%. The output differences due to polarization fluctuation are less than 1.7% and 3.2%     

Fabrication of Polymer Nonlinear Directional Coupler by Photo—bleaching

The preparation of a nonlinear directional coupler in polymer PMMA/DRl film by photobleaching is studied.We find it easier to obtain a required coupling length by controlling photo-bleaching time than by controlling the dimension of the coupler.The transmittance of each arm is measured when the pulse input light energy changes in our experiment.The experimental results show that the coupling length will change with the intensity of input light due to optical nonlinearities of the polymer PMMA/DRl at 1064 nm.     

Analysis and Simulation of S-shaped Waveguide in Silicon-on-insulator

The simulation and analysis of S-shaped waveguide bend are presented.Bend radius larger than 30 mm assures less than 0.5 dB radiation loss for a 4-μm-wide silicon-on-insulator waveguide bend with 2-μm etch depth.Intersection angle greater than 20° provides negligible crosstalk (<-30 dB) and very low insertion loss.Any reduction in bend radius and intersection angle is at the cost of the degradation of characteristics of bent waveguide and intersecting waveguide, respectively.     

A Design Analysis of Split-folded Waveguide Slow-wave Structure†

A design analysis of the split-folded waveguide structure for high power M-type tubes is presented. The theory predicts the existence of two slow-wave modes that are corroborated experimentally. A scheme of modifying the slow-wave structure is presented that eliminates the unwanted upper band and increases the bandwidth of the lower band considerably.     

Design and Analysis of 4×4 Arrayed Waveguide Grating Multiplexer

The operation principle of an arrayed waveguide grating(AWG) multiplexer is introduced and the 4×4 AWG with following design parameters is discussed in detail, such as the choice of wavelength, the neighboring arrayed waveguide distance ΔL, the channel frequency interval Δf, and the free spectral range. The structure of 4×4 AWG is designed and the result of stimulated test is also given. Analysis shows that the 4×4 AWG is characterized by a wide dynamic range, low crosstalk, better spectrum properties, and a compact structure.     

Performance Analysis of Using ATM LSR to Implement MPLS

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A 400–500 GHz Balanced SIS Mixer with a Waveguide Quadrature Hybrid Coupler

We have developed a 400–500 GHz low-noise balanced SIS (Superconductor Insulator Superconductor) mixer, which is based on a waveguide RF quadrature hybrid coupler. The RF quadrature hybrid was designed and fabricated as a broadband hybrid with good performance at 4 K. The fabricated RF quadrature hybrid was measured at room temperature with a submillimeter vector network analyzer to check amplitude and phase imbalance between two output ports. Then the balanced mixer was assembled with the RF hybrid, two DSB mixers, and a 180° IF hybrid. Several important parameters such as noise temperature, LO power reduction, and IF spectra were measured. The LO power reduction is defined as how much LO power the balanced mixer saves compared with a typical single-ended mixer. The measured noise temperature of the balanced mixer was ~ 55 K at the band center which corresponds to ~ 3 times the quantum noise limit (hf/k) in DSB, and ~ 120 K at the band edges. The noise performance over LO frequency was almost the same as that of the worse DSB mixer used in the balanced mixer. In addition the LO power required for the balanced mixer is ~ 11 dB less than that of the single-ended mixers.     

Characteristic Analysis of Diffraction from the Restricted Output End Surface of Single Mode Planar Waveguide

As for single mode symmetric step refractive index structure dielectric planar optical waveguide, when its output end is restricted, the diffractive field distribution is derived. It can be expressed as the convolution between the Dirac function and the Sinc and Lorenz functions. It is helpful to deepen the recognition of the restricted diffraction. The characteristic of the diffractive field is discussed. The variational curve of the full angle width at half maximum intensity of central bright fringe versus the half width of slit is presented by numerical calculation, and the fitting curve with the exponential function is close to it.     

On Calculation of the Amplitude–Phase Distribution of the Field Radiated from an Open End of a Rectangular Dielectric Waveguide

The problem of calculating the amplitude–phase distribution of the field radiated from an open end of a rectangular dielectric waveguide expanding along one of its sides (a plane dielectric horn) is considered. The problem of diffraction on the junction of a feed dielectric waveguide and the horn is solved by the domain decomposition method using a model in the form of a screened dielectric waveguide. The amplitude–phase distributions over the distance from the end of the radiator are studied. The possibility of using the screened model for solving the problem of radiation from the open end of a dielectric horn is shown.     

Conformal Wavelet Finite-difference Time-domain Algorithm for Analysis of Milimeter Wave Attenuation on Coplanar Waveguide

Addressed is the calculation of millimeter wave attenuation on coplanar waveguide（CPW）. A novel conformal wavelet finite-difference time-domain（CWFDTD） algorithm is proposed with emphasis on its application in calculation of millimeter wave attenuation on CPW, which is the combination of conformal algorithm dealing with the deformed cell with Wavelet-FDTD using multi-resolution analysis（MRA）. Derived is the difference formulation for multi-resolution time domain（MRTD） based on Daubechies wavelets, and also given is the stability conditions for wavelet-FDTD algorithm. To validate its accuracy and efficiency, this novel method is applied to calculate the millimeter wave attenuation on lithium niobate CPW. Numerical results demonstrate that this new CWFDTD algorithm has the same accuracy with the conformal finite-difference timedomain（CFDTD） and conformal finite-difference time-domain based on alternating-direction implicit method （ADI-CFDTD）, but saves computational time and computer memory.     

Microstrip Antenna–Oscillators Integrated with a Waveguide Built in a Dielectric Substrate

The design of a microwave oscillator based on a microstrip log-periodic antenna integrated with a field effect transistor and a waveguide built in a dielectric substrate has been developed and analyzed. The waveguide geometry provides the possibility of propagation and radiation at both the fundamental frequency of the log-periodic antenna and harmonics. Computer simulation of the oscillator design in a frequency range near resonance frequencies of the log-periodic antenna is conducted. The possibility of summation of powers of several antenna–oscillators arranged ias a linear phased array is investigated.     

Analysis and Optimum Design of Differential Inductors Using Distributed Capacitance Model

A distributed capacitance model for monolithic inductors is developed to predict the equivalently parasitical capacitances of the inductor.The ratio of the self-resonant frequency (fSR) of the differential-driven symmetric inductor to the fSR of the single-ended driven inductor is firstly predicted and explained.Compared with a single-ended configuration,experimental data demonstrate that the differential inductor offers a 127% greater maximum quality factor and a broader range of operating frequencies.Two differential inductors with low parasitical capacitance are developed and validated.     

The Stability Analysis of Multimedia Playout Synchronization Using Buffer Level Control

1　Introduction　Multimediareferstothepresentationofcollectionsofbothstaticanddynamicdatainaspecifiedorderandtime[5] .Therefore ,therearewelldefinedtemporalrela tionshipsbetweenMediaUnits(MUs) .Mediacanbeonlyplayedwellwhenthesetemporalrelationshipsarepreservedatpresentationtime .Unfortunately ,afterthetransportationoverbest effortnetworks,thedelayjitterdestroysthetemporalrelationshipsbetweenperiodicallytransmittedMUs .Network jitter ,end systemjitter,clockdriftandchangingnetworkconditionsof…     

Time–Frequency Analysis of Multichannel Signals Using Two-Sided Autoregressive Modeling

In this paper, we propose a time-varying vector two-sided autoregressive (VTAR) model for time–frequency analysis of multichannel signals. The multichannel approach is suitable in many applications, such as electroencephalogram analysis and spatial data processing, where the signals are recorded from several sensors, giving rise to vector or multichannel processes. In VTAR modeling, the current sample of the signal in some channel is estimated by a symmetrically weighted sum of past and future samples of this channel as well as of the other channels. The multidimensional VTAR parameters are assumed to be time varying and they are modeled as a linear combination of a set of basis functions. The recursive least-squares algorithm is used to estimate the coefficients of the linear combination. The VTAR model requires a smaller order than the conventional vector autoregressive (VAR) model to achieve better resolution in the time–frequency plane. Numerical examples are given in order to compare the VTAR-based time–frequency distribution with the conventional VAR-based time–frequency distribution and the Choi–Williams distribution.     

Theory of Fiber Fluorescence and Wavelet Analysis Using in the Measurement of Bio-medical Temperature

The method of the temperature measurement based on the fluorescence lifetime and fiber transmitting technology is proposed. The certain or uncertain relationship between temperature and optical characteristics of some fluorescence material excited by function pulse or square-wave pulse, and the temperature relativity of the feature are analyzed. The method based on the wavelet transformation theory is given to acquire temperature signals accurately and to remove the noise.     

Transient Thermal Analysis of Ridge Waveguide InAsP／InGaAsP MQW Lasers Operating in Pulse Driving Conditions

The transient thermal characteristics of the ridge waveguide InAsP/lnGaAsP MQW lasers, especially in various pulse driving conditions, have been simulated by using FEM. The temperature at the active core of the laser versus the time has been calculated as well as pulse width dependence of the apparent thermal resistance. The results show that the thermal characteristics of the lasers are related to both the thermal conductivity and the specific heat of the materials.     

Performance Analysis of CSS Over α–η–μ and α–κ–μ Fading Channel Using Clustering-Based Technique

Wireless Personal Communications - Cooperative spectrum sensing (CSS) is an efficient method, which is used to detect the presence/absence of primary user (PU) signal in the received spectrum at...     

Extracting Epileptic Feature Spikes Using Independent Component Analysis

In recent years, blind source separation （BSS） by independent component analysis （ICA） has been drawing much attention because of its potential applications in signal processing such as in speech recognition systems, telecommunication and medical signal processing. In this paper, two algorithms of independent component analysis （fixed-point IC,4 and natural gradient-flexible ICA） are adopted to extract human epileptic feature spikes from interferential signals. Experiment results show that epileptic spikes can be extracted from noise successfully. The kurtosis of the epileptic component signal separated is much better than that of other noisy signals. It shows that ICA is an effective tool to extract epileptic spikes from patients＇ electroencephalogram EEG and shows promising application to assist physicians to diagnose epilepsy and estimate the epileptogenic region in clinic.