Yu-nan Sun

Modulation based cells distribution for visible light communication.

Cells distribution for visible light communication can enhance the capacity of the data transmission by the reuse of optical spectrum. In this paper, we adopt three modulation formats as OOK, PPM and PWM for neighboring cells A, B and C respectively. The prototype experiment results demonstrate the error free transmission of 1.0 Mbit/s and 6.25 Mbit/s visible light communication system with our scheme. With the available LED, we can expect that the data rate of a visible light communication system with seamless connectivity can be up to 71.4 Mbit/s.

A Multi-Fork Z-Axis Quartz Micromachined Gyroscope

A novel multi-fork z-axis gyroscope is presented in this paper. Different from traditional quartz gyroscopes, the lateral electrodes of the sense beam can be arranged in simple patterns; as a result, the fabrication is simplified. High sensitivity is achieved by the multi-fork design. The working principles are introduced, while the finite element method (FEM) is used to simulate the modal and sensitivity. A quartz fork is fabricated, and a prototype is assembled. Impedance testing shows that the drive frequency and sense frequency are similar to the simulations, and the quality factor is approximately 10,000 in air. The scale factor is measured to be 18.134 mV/(°/s) and the nonlinearity is 0.40% in a full-scale input range of ±250 °/s.

An Enhanced Soft Value Calculation for LDPC Coded Pulse-Position-Modulation

In this letter, a simplified soft value extraction algorithm for LDPC coded PPM modulated signals is presented. The Monte Carlo simulations are applied to get the BER curves of the system based on the simplified AWGN channel. Through rearranging the soft value by the exponential function, we get an even better performance of the system.

Analysis of the Influences of Polarization-dependent Nonlinear Gain and Nonlinear Polarization Rotation on Optical Sampling in Semiconductor Optical Amplifier

A new theoretical model is presented to describe polarization-dependent nonlinear gain in semiconductor optical amplifiers (SOAs) on subpicosecond timescales. Based on this model, the influences of nonlinear polarization rotation (NPR) on pulsed four-wave mixing (FWM) in SOA used for optical sampling are discussed. The numerical results are in good agreement with reported experimental measurements

Novel Structure of Double-H Tuning Fork for Dual-Axis Quartz Micro-Electro-Mechanical System Angular Rate Sensor

A novel structure of a double-H tuning fork for an angular rate sensor, which can detect two-axial angular rates on a single quartz chip, is proposed in this article. Multiple sensing forks, which are separated from driving forks, guarantee the sensitivities of the two-axial effect and suppress couplings among each mode. Simulation with the finite element method (FEM) is used to analyze the resonance frequencies, electrode distributions, and outputs of this structure. The results show that this double-H tuning fork resonator can be used as an angular rate sensor to detect two-axial angular rates effectively.

Trellis-coded pulse amplitude modulation for indoor visible light communication

Trellis-coded pulse-amplitude modulation (TC-PAM) is applied in visible light communication (VLC) system using RGB-LED. Based on natural modulation, we propose a modified modulation to yield performance enhancement. Further, a decoding method of combing soft-decision Viterbi algorithm with most significant bit (MSB) decoding is developed. Finally, the results of Monte-Carlo simulation are presented to verify the best modulation and decoding method among the mentioned modulation and decoding techniques.

Research on illuminance distribution of LED spherical arrays for indoor visible light communication

Illuminance distribution of LED spherical arrays is studied by theoretical analysis and simulation. The optimal layout of the LED spherical array is founded by changing the angle, the ball radius, and the power of different LED. The uniformity of illumination of the LED spherical array is verified, which is better than LED planar array. In addition, the illuminance distribution of indoor ground surface illuminated by LED spherical array with different parameters and the related curves are obtained. The LED spherical array mentioned in this paper can be useful in the application of indoor visible light communication.

A novel scheme for simultaneous transmission of 10-Gb/s baseband and 20-GHz microwave signals in radio-over-fiber system

To simultaneously modulate and transmit 10-Gb/s baseband and 20-GHz microwave signals on a single wavelength using single-sideband (SSB) modulation technique, a novel ROF scheme is proposed and verified by simulation. Based on a Dual-Parallel Mach-Zehnder Modulator (DPMZM) the scheme can carry the microwave signal on the upper sideband(USB) and the baseband signal on the lower sideband(LSB). It is to be seen from the simulated results that the crosstalk between the signals with dual services is very small. By means of subcarrier-multiplexing (SCM) technique, the optical 20-GHz microwave wave carrier is generated to carry 155-Mb/s baseband signal and 10-Gb/s baseband signal is imposed on the original optical carrier via SSB modulation. The simulated results of BER and the eye diagram are achieved separately. The signals with dual services are successfully transmitted over 50-km single-mode fiber.

The optical sampling based on semiconductor optical amplifier for optical performance monitoring

Progress in optical network has stimulated interest in optical performance monitoring (OPM). Optical sampling technique is believed to be a promising candidate to monitor the physical state of the network. The theoretical model of a monitoring system based on optical sampling in semiconductor optical amplifier (SOA) and software synchronized algorithm is constructed. Compared with the results obtained by Optsim, the monitoring system model is proved. For 10Gb/s NRZ (RZ) optical signals, the differences on Q values between the results obtained by SOA and the ideal sampling processes are 0.195dB (0.247dB), 0.988dB (0.594dB), and 1.707dB (0.596dB) for pump energy equal to, ten times of and fifty times of the optical data signal energy respectively. The sampling device can induce degradations of the sampling results. It is mainly because of the gain saturation and the nonlinear effects in SOA. The high input power can make the gain saturated deeply and further influence the probe and conjugate outputs. At the same time, the pump power should not be too low. The proper pump power will obtain better sampling linearity and better sampling results.

MMI power splitters based on the annealed proton exchange (APE) technology

The MMI optical power splitters which are based on the self-imaging effect (SIE) have been analyzed in the paper, and 1×4 MMI power splitter is designed. The designed device is simulated and optimized by Beamprop software, the simulation results are basically agreement with the designed effect, the excess loss induced by multimode interference is less than 0.04dB, uniformity is about 0.01dB.The low loss and fine uniformity MMI power splitter has been made by Lithium Niobate annealed proton exchange technology, and the experiment sample measurement results are achieved.