Abstract:A wavelength converter based on the self phase modulation(SPM) effect in highly nonlinear microstructure fibers(MFs) is proposed.The core diameter and the pitch of the fiber are 2.05 μm and 5.0 μm,respectively,and the diameter of the airholes in the fiber cladding is 4.50 μm.The calculating nonlinear coefficient is 112.2 W-1 km-1 and it is 11 times higher than that of a conventional dispersion-shift fiber and 56 times higher than that of a conventional single-mode fiber.The length of the fiber i...

Abstract:Chaos-based algorithms are proven to have advantages in image encryption.In this paper,a new algorithm mixing Logistic map,Henon map and Lorenz system is presented.Signals from two discrete chaotic maps,Logistic map and Henon map,are mixed proportionately and sent to a continuous Lorenz system to generate a chaotic sequence.Then,by masking the image data with this sequence,the encryption is realized fast and simply.Experimental tests are carried out with detailed analysis,which demonstrates the ...

Abstract:Ultrawide ZnSe nanoribbons are synthesized by the simple thermal evaporation. The microstructure of ZnSe nanoribbons is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), photoluminescence (PL) and Raman spectrum. It is found that the strong emission near the band gap of ZnSe centered at 460 nm is obtained in these nanoribbons. More importantly, ZnSe nanoribbons can act as lasing emitting optical cavities. Raman studies indicate that the longitudinal optic (LO) and transverse optic (TO) phonon confinements of the ZnSe nanoribbons shift to lower frequency.

Abstract:A white organic light emitting device (WOLED) combining the blue organic light emitting device with a red color conversion layer (CCL) is reported, which includes a fluorescent material N-(4-((E)-2-(6-((E)-4-(diphenylamino) styryl)naphtha len-2-yl)vinyl) phenyl)-N-phenylbenzenamine (N-BDAVBi) doped into 4,4′-N,N′-dicarbazole-biphenyl (CBP) as the blue light emitting layer, and the poly (2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylene vinylene (MEH-PPV) as a red CCL. By optimizing the concentration of MEH-PPV in the CCL, a good white light emission is obtained, which shows that the stable CIE coordinates of (0.33, 0.34) will have a slight change when the driving voltage is increased from 6 to 11 V. The maximum brightness and current efficiency of the optimized device are 11294 cd/m² and 6.4 cd/A, respectively.

Abstract:A novel narrow-band filter based on the dual-core doped photonic crystal fiber is proposed. By optimizing structure parameters of the photonic crystal fiber, the index curves of the fundamental modes for the two cores are crossed at 1.55 μm and the wavelength-selective coupling is achieved. The characteristics of the filter are numerically simulated by the full-vector beam propagation method. And the simulation results show that the coupling length and the bandwidth of the filter are 16.4 mm and 9 nm at −3 dB loss, respectively. It demonstrates the advantages of the filter with a small size, a low transmission loss and the narrow-band width.

Abstract:The degradation of phenols has become urgent issues. In this paper, the diamond film electrode modified by photochemistry is chosen as the research object for phenol degradation. The boron-doped diamond films, which are modified and unmodified, are characterized by the X-ray photoelectron spectroscopy (XPS). Cyclic voltammograms are used to test the electrochemical window. It is found that the current value of tantalum/boron-doped diamond (Ta/BDD) electrode with amino modification increases two orders of magnitude in degrading the nitro-phenol, when the amino-modified rate is only 1.9%. The current value is enhanced from −4.0 × 10⁻⁴A-4.0 × 10⁻⁴ A to −4.0 × 10⁻²A-4.0 × 10⁻²A. In addition, in order to understand the excellent characteristics of Ta/BDD electrode modified by photochemistry for phenol degradation, the efficiency of degradation is also discussed.

Abstract:Mode characteristics of hexagonal resonators are numerically simulated by the two-dimensional (2-D) finite-difference time-domain (FDTD) technique. For the hexagonal resonator with the side length of 3 μm and the refractive index of 3.2, the mode quality (Q) factors decrease from 10⁴ to 10² as the resonant wavelength increases from 1.1 to 3.2 μm. The modes have a relatively high Q factor as their even and odd states have different mode wavelengths and different Q factors, i.e., they are accidentally degenerate modes. The azimuthal mode numbers obtained from mode field distribution for the accidentally degenerate modes satisfy the mode number relation derived from the symmetry characteristics for the split of double-degenerate modes. Furthermore, the numerical results indicate that an output waveguide parallel to one of the sides is the better scheme for directional emission. For the hexagonal resonator with 3 m side length and 0.3 μm wide output waveguide, the Q factor of 5.05×10³ and output efficiency of 33% are obtained at the mode wavelength of 1.29 μm.

Abstract:A simple set searching optimization algorithm is proposed for Er³⁺-Yb³⁺ co-doped fiber lasers in this paper. This method enables fiber lasers to acquire the optimum fiber length and Yb³⁺-Er³⁺ concentration ratio for a given accuracy. The numerical results illustrate that the optimum Yb³⁺-Er³⁺ concentration ratio changes very little, the optimum fiber length shortens and the corresponding output power is increased with erbium ions concentration increasing. The total Yb³⁺ and Er³⁺ contents are nearly constant under certain pump power, while the optimum total erbium ions and ytterbium ions are decreased with pump power decreasing.

Abstract:A novel resonant cavity enhanced (RCE) photodetector with flat-top and steep-edge response is presented. The response is obtained by designing a gradient-thickness P area in the absorption cavity. Simulation results show that the maximum and minimum values of the quantum efficiency in bandpass are 85.242% and 87.564% respectively, the ripple is about 3.6%, and 0.5 dB, 3 dB and 20 dB bandwidths are 0.3 nm, 0.4 nm and 1.2 nm, respectively. The mesa area is 10 μm × 10 μm and the frequency response bandwidth is 87 GHz. Compared with similar photodetectors, this photodetector has high quantum efficiency, narrow spectral response linewidth, good flat-top and steep-edge response and ideal high-speed characteristics.

Abstract:An integrated optical chip for fiber optical gyroscope (FOG) is designed and fabricated on GaAs. To achieve a high modulation efficiency and a small chip size, a deeply etched waveguide structure is employed, and accordingly a multimode interference (MMI) coupler is used as the 1 × 2 power splitter. The size of the chip is about 8.5 mm × 0.5 mm, which is much smaller than that of LiNbO₃-based chips. The experimental results show that the extinction ratio (ER) of the TE mode to the TM mode is over 26 dB and the value of V _π·L of the phase modulators is 18 V · cm. The method to further lower V _π is discussed.

Abstract:A vectorial finite element method (VFEM) is adopted to investigate the novel single-polarization single-mode (SPSM) photonic crystal fiber (PCF) coupler which has asymmetric dual-core and two lines of enlarged air holes. It is demonstrated that the SPSM region of the designed fiber can be more than 250 nm wide with a set of optimized air-hole parameters and the width of the SPSM region could change slightly by fine adjustment of the inner large air holes. The coupling length between the odd and even x-polarization modes is also investigated through fine-tuning the large and small air-hole diameters.

Abstract:A light-controlled oscillating array for retina prosthesis is presented. The unique advantage of the circuit is that it has a lower voltage and ultra-low power consumption. And it has some other features as below: it is applicable to the natural light illumination and each pixel is an independent oscillator whose frequency is proportional to the intensity of the incident light. The fundamental characteristics of the circuit are analyzed. It is fabricated with a standard 0.6 μm CMOS technology. The experimental results indicate that the proposed circuit can be used for retina implantation, taking the place of the suffered photoreceptor in the retina of the blind and partially recovering the blind’s eyesight.

Abstract:The photonic band gap (PBG) structures of four types of annular photonic crystals (PCs) with inner-scatter of rectangular, square, hexagonal and circle shapes are respectively calculated by the plane wave expansion method. The optimal samples with the largest gap-midgap ratio for each structure are obtained by scanning the four parameters: filling ratio f, dielectric constant ɛ₁, rotating angle θ of inner-scatters and outside radius R of the air ring. The results show that the band gap can be further maximized by adjusting the structural parameters, and a wide PBG with the gap-midgap ratio of 20.4% is gained in the annular photonic crystal with rectangular inner-scatters.

Abstract:C-axis oriented ZnO films are deposited on polished diamond substrates in various O₂/(O₂+Ar) ratios using the radio frequency (RF) magnetron sputtering technique and are subsequently annealed in oxygen ambience under the same conditions. Structural, morphologic and electrical properties of ZnO films are characterized by X-ray diffraction (XRD), high-resistance instrument, energy dispersive X-ray spectroscopy (EDS) and scanning electronic microscopy (SEM). As the O₂/(O₂+Ar) ratio increasing from 1/12 to 5/12, the crystallinity of the as grown ZnO films becomes better and the electrical resistivity increases slowly. After annealing, the ZnO films deposited in O₂/(O₂+Ar) =1/12 and 3/12 are improved greatly in crystallinity, and their electrical resistivity is enhanced by two orders of magnitude, while those deposited in O₂/(O₂+Ar) =5/12 are scarcely changed in crystallinity, and their resistivity is only increased by one order. In addition, the ZnO films deposited in O₂/(O₂+Ar) =3/12 and annealed in oxygen are with the best crystal quality and the highest resistivity.

Abstract:The hydrogen passivation is adopted to enhance the performance of poly-Si crystallized by YAG laser annealing (LA poly-Si). The effects of passivation time, passivation power and passivation temperature on the hall mobility of the LA poly-Si are investigated and the mechanism of the hydrogen passivation is preliminarily analyzed. It is found that the effect of the hydrogen passivation on the qulity of YAG laser annealed poly-Si is also correlated with the deposition method and the defect type in it.

Abstract:p-cycle is one of the most promising technique of span protection in optical transport networks with mesh-like efficiency and ring-like speed. Longer p-cycle provides better efficiency in term of spare capacity, but longer restored path increases end-to-end propagation delay, which reduces the reliability of the restored network. Hence, minimization of restoration path is a critical issue in p-cycle based protection network. In this paper, two new dynamic reconfiguration approaches namely inter-cycles switching (ICS) and local restoration paths (LRP) are discussed to reduce the length of restored paths in existing optimal spare capacity design of p-cycle. Both proposed approaches are meant to utilize the idle p-cycles thus significantly reducing the path length. This reduction in restored path length also releases the redundant spare capacity.

Abstract:In this paper the indoor visible light communication (VLC) multipath channel model is analyzed. A new reflection model based on the Lambert-Phong pattern is presented by investigation of the reflection characteristics. Through the Monte-Carlo ray tracing simulation based on the Lambert-Phong pattern, the VLC optical channel models are set up, including the single source and multiple-source systems. The simulation results show that using the Lambert-Phong reflection pattern, the calculation becomes linear to the number of reflections and the computation complexity is decreased.

Abstract:In the multi-service requirement of the next generation of optical networks, differentiated services should be provided, and the transmission quality of signal and the path reliability are two important parameters of service class differentiation. A new dynamic routing and wavelength assignment (RWA) algorithm supporting service-differentiated provision, which takes account of both requirements of the signal transmission quality and the path reliability, is proposed. The numerical results from simulation show that the algorithm can not only overcome the impact of impairment on signal transmission quality and guarantee lightpath reliability, but also offer the service-differentiated lightpath according to its class.

Abstract:According to the autocorrelation function (ACF) of dynamic light scattering (DLS) signals, the exponential model used for scattering signal simulation can be established. Based on this model, nine kinds of DLS signals for unimodal, bimodal and trimodal distribution particles are simulated respectively. The ACF of the simulated signal agrees with its theoretical value very well. Inverted size errors of simulative signals for unimodal distribution particles by Cumulants method and those for bimodal and trimodal distribution particles by nonnegative constraint least squares (NNLS) are less than 0.13%, 2.11% and 3.01%, respectively. Comparing the exponential model with autoregressive (AR) model, the calculation time of the former is less than one tenth of the latter. Hence, the exponential model is more effective in the simulation of DLS signals.

Abstract:An improved demodulation system for fiber Bragg grating (FBG) sensors based on the wavelength pumped multiplexing (WPM) filter is presented. Double photoelectric measurement channels are exploited to compensate the surrounding and light source interference including temperature influence. Temperature testing is employed to prove the demodulation system capacity and characteristics. The digital thermometer and one free FBG are simultaneously introduced in the constant-temperature water tank for the comparison study. The results show that the demodulation scheme can measure temperature with a high resolution, stability and reliability. Its sensitivity of temperature measurement can reach 0.05 °C in repeated testing.

Abstract:A novel porous silicon based optical Fabry-Perot cavity structure is prepared as a label-free immunosensor platform for detecting antigen-antibody. The lagurus zona pelluciad 3 (LZP3) and the specificity of the polyclonal anti-LZP3 antibodies are employed in our laboratory as the target and the probe, respectively. Firstly, the antibodies are immobilized to the porous silicon optical cavity using silanization and glutaraldehyde (GA) chemistry. And then, after the antigen-antibody reaction, it is monitored that the red shift of the reflection spectrum of the immunosensor increases with the antigen concentration. This research also plays a potential role for the extensive applications in immunoassay.

Abstract:The influence of polaron effects on the effective potential of weak-coupling exciton in semiconductor quantum dots (QDs) is studied based on the Lee-Low-Pines-Huybrechts variational method. The results show that the effective potential of the exciton consists of three parts: coulomb potential, induced potential and confining potential. Numerical calculations for the GaAs quantum dot, as an example, are performed. The result indicates that the effective potential of the exciton increases with the electron-hole distance. It is found that the polaron effects have remarkable influence on the states of the exciton: helpful to the stability of the light-hole exciton, but unfavorable to the stability of the heavy-hole exciton.