Polarimetric Distributed Feedback Fiber Laser Sensor

With maturity of the fiber technology and enhancement of the fiber grating application capabilities, performance of the fiber laser has been greatly improved. It is widely used with temperature measurement, pressure measurement, strain measurement in optical fiber sensing fields. Distributed feedback (DFB) fiber lasers and distributed Bragg reflector (DBR) fiber laser are two kinds of common linear cavity fiber laser. Compared with the DBR fiber laser,the advantages of the DFB fiber laser is achieved wavelength selective and optical feedback by only one grating . Not only its frequency stability is perfect, but also avoiding splicing loss between the doped fiber and grating. These make the DFB fiber laser applications more widely in the sensing fields.This paper mainly studies on the characteristics of DFB fiber laser beat frequency. This paper proposes it is feasibility, which DFB fiber laser applies in the sensor fields by experiments. Unlike conventional passive sensors, this article exploit an active fiber laser to sensor unit, the parameters outside (temperature, pressure, twist, strain) applied to the DFB fiber laser cavity, making the beat frequency change of the orthogonal polarization DFB fiber laser. Experiments make use of beat frequency as sensor signals to achieve measurements of the external parameters.Firstly, this paper makes a brief introduction about the DFB fiber laser and the polarization properties, tests the relevant characteristics of DFB fiber laser by actual experiments, such as the relationship between DFB fiber laser wavelength, wavelength amplitude and pump power, fiber laser temperature characteristic curve. Then this article makes comprehensive exposition about principles and advantages of dual-frequency DFB fiber laser and analyzes sensing mechanism for pressure, temperature, twist and strain.Dual-frequency DFB fiber laser sensor is the focus of this article. We complete designs and experiments of the pressure sensors, temperature sensors, twist sensors by using orthogonal dual-frequency DFB fiber laser as sensor unit to achieve kinds of physical measurements. We also get a better sensitivity, prove the feasibility of the sensor system, and achieve a wide development of sensing applications.