Huafeng Zhao

A novel method for simultaneous measurement of current and voltage using one low-birefringence fiber

Abstract A novel method for simultaneous measurement of current and voltage employing a single monomode low-birefringence (Lo-Bi) fiber is described. This uses the Faraday effect for detection of current and the Kerr effect for detection of voltage. The waveform of the output light intensity due to the Kerr effect has been detected and the Kerr constant was measured as 5.4×10−16 m/V−2 at 25°C. Theoretical analysis shows that the current component can be measured free from the influence of the voltage component and the two components can be easily separated.

Fiber sensor for simultaneous measurement of current and voltage by single Lo-Bi fiber

A sensor using a single monomode low-birefringence (Lo-Bi) fiber for simultaneous measurement of current and voltage has been designed, which uses Faraday effect for detection of current and Kerr effect for detection of voltage. Theoretical analysis proved the current component can be measured free from the influence of the voltage component, and the two components can be easily separated. Experimental results demonstrate the feasibility of the Kerr effect of the Lo-Bi fiber for sensing voltage, which is the main point in this proposal.

Laser induced breakdown spectroscopy algorithm using weights iteration artificial neural network

Laser-induced breakdown spectroscopy (LIBS) was applied to quantitative analysis of heavy metal pollution elements in soil. The artificial neural network (ANN) algorithm is used to the processing of the complicated spectrum lines of soil. In this paper we developed a new algorithm using weight iteration in the artificial neural network, so as to decrease the training epochs remarkably. The spectrum line intensity of some elements, such as Cu, Cd, Al, Fe and Si, were obtained. The limits of detection for trace elements Cu and Cd in soil were determined to be 42 and 5ppm, respectively.

Wavelength Control System of Widely Tunable SG-DBR Lasers

According to the wavelength tuning characteristic of widely tunable sampled grating distributed Bragg reflector (SG-DBR) lasers, a kind of wavelength control system is developed. A look-up table, the file including data of picked operation points, is established to store the relationship between lasing wavelengths and tuning currents for each SG-DBR laser in the system. By rapidly looking up the look-up table and providing the corresponding driving currents, the particular lasing wavelength of SG-DBR laser is obtained. Wavelength tuning experiments have been done with eight SG-DBR lasers, and the results show that this system has high precision of wavelength control.

A novel model to analyze temperature dependence of HiBi fiber and its application to PMD emulator

We present a novel model using Jones matrix method to describe the temperature dependence of high-birefringence fiber. We also apply the model to a temperature dependent PMD emulator with 12 sections of HiBi fibers directly spliced at fixed orientations. From numerical simulation and experiment, we get ideal DGD statistical distribution, second order PMD statistical distribution and the frequency autocorrelation function.

Single-LED optical fiber sensor system using a novel polarization-modulated compensation technique

A novel compensation technique for polarization-modulated optical fiber sensors is proposed, which employs a single LED to provide the measurement and the reference signals. In the sensor head, a polarization beam splitter is used not only as a polarizer, but also as an analyzer, and the reflective structure is used so that the sensor head is simple, compact and reliable. A loss-compensated temperature sensor based on the thermal effect of birefringent crystal is demonstrated. The experimental results show that this compensation technique can stabilize the sensor output with a high accuracy and better long-term stability.

Simulation and experimental research on modal analysis for a new 5-axis superalloy blade machine tool

This paper considers a new type of 5-axis machine tool which is used to cut superalloy blades specially. Referring to this new structure system, this study presents modal simulation in detail to calculate the structure vibration resistance. The modal simulation include building suitable finite element models, considering boundary constraints and interpreting results. The physical impact test of prototype is conducted to validate the simulation results. The modal simulation also reveals that some important partial characteristics that affects the structure performance are ignored in the physical test data. The validated model can be used to complement the experimental test.

An absolute frequency reference in exact multiples of 100 GHz by calibrated F-P etalon

1.5μm wavelength region is the window of optical communication. Absolute frequency references that satisfy ITU-T standards in 1.5 μm region for frequency calibration are widely needed in DWDM system. In this paper, an approach of obtaining precise frequency points which ITU-T has produced has been experimented, using an acoustic frequency shift, by calibrating Fabry-Perot etalon using double acetylene absorption lines. In the experiment, mode 1955 of F-P etalon is offset frequency-locked to acetylene absorption line P14, 195500.4023GHz, with frequency stability 108 for a 30-minute measurement. After calibrating, a series of spaced 100GHz artificial absolute frequency references in 1.5μm region are obtained.

Dynamic analysis of large single characteristics of sampled-grating DBR lasers integrated with EAM and SOA: time-domain modeling and experiments

The wide tunability and the dynamic properties of the SG-DBR have been simulated using a numerical time-domain dynamic model. The experimental results of the SG-DBR tuning map and mode stable characteristic have been investigated.

Calibrated Fabry-Perot etalon as 1.5-μm wavelength region absolute frequency reference based on double acetylene absorption lines

Absolute frequency reference in 1.5-μm wavelength region is very useful for DWDM system. We have studied on producing artificial 1.5-μm wavelength region absolute frequency reference by calibrating the F-P etalon. Double acetylene absorption line calibrating technique was adopted. An experiment of calibrating the Fabry-Perot etalon using double acetylene absorption lines has been demonstrated. In the experiment, Mode 1996 of the F-P etalon was locked to acetylene absorption line 1533.4621 nm. The frequency stability of the calibrated F-P etalon was about 7×10-8. After calibrating, a series of artificial absolute frequency references in 1.5-μm wavelength region was obtained. To reduce the complexity of calibrating, a novel frequency difference measurement method was introduced.