title: A Time Difference Method for Measurement of Phase Shift between Distributed Feedback Laser Diode (DFB-LD) Output Wavelength and Intensity.
abstract: A time difference method to conveniently measure the phase shift between output wavelength and intensity of distributed feedback laser diodes (DFB-LDs) was proposed. This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation. For its practical implementation, a measurement example of phase shift was demonstrated by measuring a time difference between the first time and the second time attendances of the same gas absorption line in the intensity-time curve during one sine or triangle modulation circle. The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π. As the modulation frequency increased the shift value increased with a slowed growth rate.
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. Liuyongning1990@163.com.
authors.forename: Yongning
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. changjun@sdu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Chang
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. lianjie@sdu.edu.cn.
authors.forename: Jie
authors.initials: J
authors.lastname: Lian
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. zhaojunliu@sdu.edu.cn.
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Liu
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. iamwq1989@gmail.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan 250100, China. 2003410572@163.com.
authors.forename: Cunguang
authors.initials: C
authors.lastname: Zhu
keywords: DFB-LD; fiber optics sensors; infrared spectroscopy; phase shift