An optical alignment-free and highly accurate method is employed to measure the magnetic field-dependent refractive index of magnetic fluid （MF） in bulk. The measured refractive index decreases significantly with the increasing magnetic strength and then tends to saturate in the high intensity range. By applying a tunable magnetic field ranging between 0 and 1661 Oe, the maximum shift of the refractive index of MF in bulk is found to be 0.0231.
The visibility in magnetostrictive fiber-optic interferometric sensors using a Gaussian laser beam is analyzed. It is shown that the conventional Gaussian laser beam has little influence on the visibility. The visibility depends strongly on the input state of polarization （SOP）. We implement a cylindrical transducer and build a measurement setup with a polarization controller. The visibility dependent on the SOP of input light is measured. The estimated values are similar to the experiment results, which verifies the analysis.
Polarization effect in parametric amplifiers is studied. Coupled equations are derived from the basic propagation equations and numerical solutions are given for both one-wavelength-pump and two-wavelengthpump systems. Several parametric amplifiers driven by pumps at one wavelength and two wavelengths are analyzed and the polarization independent parametric amplifier is proposed.
通用串行总线(Universal Serial Bus,USB)是一种新兴的计算机外围串行通信接口标准,与常用的计算机接口(如串口、并口等)相比,具有热插拔、即插即用、传输速率高、可靠性好、扩展方便、成本低等优点,已成为当前计算机必备的接口,并广泛地应用于各种数码产品、计算机外设等[1].由于USB电接口的最大传输距离为5 m,使得它不能应用于远程监控、远程数据采集等场合.本文研究远程USB波分复用光收发模块,采用现场可编程门阵列进行USB协议的解析,实现了USB远程透明传输.USB光收发模块可广泛应用于远程使用USB设备的场合.
