Showing papers by "Kun Xu published in 2006"

Effects of symmetry of GaN-based two-dimensional photonic crystal with quasicrystal lattices on enhancement of surface light extraction

Abstract: We demonstrate enhancement of surface light extraction from two-dimensional photonic crystals (2D-PCs) on the electrical injected GaN-based light emitters The effects of symmetry of PCs on light extraction were studied 25 times enhancement of surface emission was obtained from the PCs with an octagonal symmetric quasicrystal lattice (8PQC) compared to that from a nonpatterned region Additionally the surface emission from PCs with dodecagonal symmetric quasicrystal lattice (12PQC) exhibited about 17 and 14 times higher emission than regular PCs with triangular lattice and 8PQC, respectively Consequently, the 12PQC provides a favorable consideration of 2D-PC in light extraction from light emitting diode

Self-Pumping Wavelength Conversion for DPSK Signals and DQPSK Generation Through Four-Wave Mixing in Highly Nonlinear Optical Fiber

Abstract: A novel scheme is proposed to achieve self-pumping wavelength conversion for two differential phase-shift keying (DPSK) signals at different wavelengths through four-wave mixing (FWM) effect in a highly nonlinear optical fiber. By changing the phase modulation depths to pi/2 for both of the DPSK signals, the two signals can be multiplexed to generate a differential quadrature phase-shift keying signal. The simulations and experimental results demonstrate the feasibility of phase manipulations for phase-shift keying signals through the FWM process

TCP performance experiment on OBS network testbed

Abstract: The TCP performance over OBS is experimentally investigated on OBS testbed. Experimental results show that TCP performance over OBS can be guaranteed in the case of 0.1% burst loss probabilities.

40 Gbit/s all-optical logic NOR gate based on nonlinear polarisation rotation in SOA and blue-shifted sideband filtering

Abstract: An all-optical logic NOR gate is presented by exploiting nonlinear polarisation rotation in a semiconductor optical amplifier (SOA) and blue-shifted sideband filtering. The NOR gate is experimentally demonstrated and simulated at 40 Gbit/s. Experimental results show high extinction ratio (ER) of about 12.2 dB with very clear and open eye. Simulation shows the scheme can provide excellent performance. The logic gate has a simple configuration and allows photonic integration.

40 Gbit ∕ s all-optical logic NOR gate based on a semiconductor optical amplifier and a filter

Abstract: A novel all-optical logic NOR gate is presented that is composed of a semiconductor optical amplifier (SOA) and an optical bandpass filter. The NOR gate is successfully experimentally demonstrated at 40 Gbit/s. The experiment result shows good extinction ratio of larger than 12.0 dB with clear and open eye. The NOR gate has a simple configuration and allows photonic integration.

Investigation of chirped return-to-zero differential phase-shift keying (DPSK) modulation format and its performance comparison with return-to-zero DPSK in 40×40-Gbit/s dense wavelength-division multiplexing transmission systems

Abstract: Chirped return-to-zero differential phase-shift keying (CRZ-DPSK) modulation format under different channel spacings is investigated and compared with RZ-DPSK in 40×40-Gbit/s dense wavelength-division multiplexing transmission systems. An optimization operation over a wide range of parameters, such as span input power, precompensation percent, and chirp parameter (only for CRZ-DPSK), is performed in the simulation. Simulation results show that CRZ-DPSK demonstrates better performance in transmission distance, nonlinear, and dispersion tolerance with wider channel spacing of 100 GHz. When the channel spacing is reduced to 75 GHz, a slight degradation is observed for CRZ-DPSK and the performances of both formats are acceptable. But when it is reduced from 75 GHz to 50 GHz, a clear degradation of the CRZ-DPSK performance is measured, but RZ-DPSK demonstrates no significant degradation.

Performance evaluation of modulation formats in 40*40-Gb/s WDM repeaterless transmission systems

Abstract: Transmission performance of six modulation formats is numerically compared in 40*40-Gb/s wavelength division multiplexing (WDM) repeaterless systems. The results indicate that return-to-zero differential phase shift keying (RZ-DPSK) (33% duty cycle) demonstrates the best performance among all the formats when the accumulated amplified spontaneous emission power (AASEP) is small. But with the increasing of AASEP, the superiority of RZ-DPSK transmission performance over the other five modulation formats is vanished. AASEP is justified to be the major source for the deterioration of the superiority.

All Optical Pulsewidth-Tunable CSRZ Signal Generation Using LiNbO3 Modulator and Time Delay Interferometer

Abstract: An all-optical scheme using time delay interferometer to generate 10 Gbit/s CSRZ modulation format signal with tunable pulsewidth is proposed and demonstrated experimentally

All-optical wavelength conversion based on nonlinear polarization rotation (NPR) in SOA and AWG filtering

Abstract: An all-optical wavelength converter, based on nonlinear polarization rotation (NPR) in semiconductor optical amplifier (SOA) and array waveguide grating (AWG) filtering, is experimentally demonstrated. The wavelength converter can provide excellent operation including extinction ratio and Q factor. The simultaneous two wavelength conversion outputs are successfully obtained at 20 Gb/s.

Sidelobes Suppression of Periodically Placed Resonators Side-Coupled to Photonic Crystal Waveguide

Abstract: Apodization technique is applied to suppress sidelobes in the reflection spectrum of periodically placed resonators side-coupled to photonic crystal waveguide. Good agreement is obtained between theoretical analysis by transfer-matrix method derived from coupled mode theory in time and simulation experiments. Furthermore, phase response of the reflection filter is investigated to analyze the transmission of pulses when applied to optical transmission system by transfer-matrix method. As a result of apodization, pulse delay appears due to decreased full-width at half-maximum of Gaussian taper function. Even asymmetric pulse with oscillatory structure is observed when the full-width at half-maximum of Gaussian taper function gets larger.

40GHz Up-conversion in Radio-over-fiber System Using a 10GHz Modulator and Birefringent Fiber Loop

Abstract: A novel up-conversion scheme is proposed and demonstrated experimentally for 2.5 Gbit/s ROF system by using a 10 GHz modulator and birefringent fiber loop. The up-conversion signals carried by 40 GHz CSRZ optical pulse are obtained

Simultaneously all-optical inverted and noninverted wavelength conversion employing SOA-based Sagnac interferometer

Abstract: This paper have successfully demonstrated an all-optical wavelength conversion scheme for all-speed return-to-zero (RZ) format data input by using a Sagnac interferometer based on semiconductor optical amplifier (SOA)The attractive issue of the proposed method is that the converted signal can be obtained simultaneously with inverted and noninverted wavelength conversion signals

Novel Modulation Formats and their Applications in High-speed Optical Transmission Systems

Abstract: Several novel modulation formats, such as DPSK and DQPSK, and their performances in high-speed optical transmission systems are demonstrated. And the application of CSRZ and RZ formats in ROF systems is also investigated.

Performance of an efficient schedule mechanism used in multi-hop optical burst switching networks

Abstract: Optical burst switching is a promising paradigm for the next-generation Internet Path length priority effect is investigated firstly of conventional JET scheme in multi-hop optical burst switching networks Then a novel scheduling mechanism with multiple queues is proposed to avoid the effect Simulation results show that a better performance is achieved