This paper analyzes and demonstrates a simplified frequency quadrupling configuration for optical millimeter-wave (mm-wave) generation, in which the electrical phase shifter and optical filter are omitted. Theoretical analysis is given to reach the optimum operating conditions including direct current (DC) bias voltage, optical transmission point of the dual-parallel Mach-Zehnder modulator (MZM) bias voltage, optical transmission point of the dual-parallel Mach-Zehnder modulator (DP-MZM), amplitude of the radio frequency (RF) driving signal and the impact of the extinction ratio (EF) on the optical sideband suppression ratio (OSSR) and radio frequency spurious suppression ratio (RFSSR). Experiments prove an OSSR of 15 dB and an RFSSR of 26 dB for the new frequency quadrupling scheme at 6 GHz, 8 GHz and 10 GHz of RF driving signal without any electrical phase shifter or optical filter. This system exhibits the advantage of low wavelength dependence and large frequency tunable range.

光声光谱法是检测气体最灵敏的方法,气体浓度检测精度可达到ppt量级,但这需要复杂的实验系统和昂贵的器材,不利于在工程实践上使用.本文基于可调激光器的电流调制特性,提出了一种在测量气体吸收谱的吸收零点和吸收峰之间有效切换波长的简单调制方法.当激光功率为2.1 mW时,甲烷气体浓度的测量极限可达到0.46 ppm,测量结果证明了双波长法的可行性.

Tianjin University of Technology and Springer-Verlag Berlin Heidelberg 2012 A calibration board composed of 8*8 near-infrared surface-mounted diodes (NIR-SMDs) (940 nm) is designed. Meanwhile, a common binocular measurement system with the average error less than 0.1320 mm is used to obtain the geometric information of this board. A calibration method with the designed pattern is performed to obtain the parameters of the nearinfrared camera (NIRC). In the experiment, the average relative errors of focal length and principal point are 0.244% and 0.735%, respectively. The mean of image residuals is less than 0.01 pixel. The error of three-dimensional (3D) measurement is less than 0.3 mm. All those results indicate that the designed calibration board is suitable and accurate for calibrating NIRC.