Optical fiber random grating-based multiparameter sensor

Abstract

A novel multiparameter fiber-optic sensor based on a femtosecond laser micromachined random grating is proposed and demonstrated to realize simultaneous measurement of temperature, axial strain, and surrounding refractive index. A wavelength-division spectral cross-correlation algorithm is adopted to extract the phase variation induced spectral shift responding to different external disturbances. Sensitivities of 10.32 pm/°C, 1.24 pm/με, and -1520.6 pm/RIU were achieved for temperature, axial strain, and surrounding refractive index, respectively. The fiber random grating without phase mask fabrication and high physical strength is an excellent alternative aiming at simple and compact multifunctional fiber sensors.

A Brief Review of New Fiber Microsphere Geometries

“…simple technology, low production cost [11], light weight, and immunity to light source oscillations [12]. These features allowed for developments in multiple areas, and applications include fiber and nonlinear optics, laser physics [11], secure optical communications [13], random number generation [14], fiber fault detection [15][16][17][18][19], and sensing [20][21][22]. For sensing, optical random signals were used for compressive sensing [22].…”

Recent Developments in Micro-Structured Fiber Optic Sensors

“…It was not until recently that the random grating is fabricated for optical sensing applications. Xu et al [260] reported a novel multi-parameter fiber optic sensor based on an fs laser micro-machined random grating to realize simultaneous measurement of temperature, axial strain, and surrounding RI. This novel random grating was manufactured by the fs laser modification processed spot by spot with random separations ranging from 0 to 3.5 µm without phase mask and critical alignment and vibration control as shown in Figure 17.…”

“…The purposes of either way are to introduce the mismatch between the mode field distributions of lead-in fiber and lead-out fiber, which spreads the energy of the core mode from the lead-in fiber out to the cladding Figure 17. (a) Experimental setup of the fs laser micro-machining system with microscopic images of the fiber random grating samples; (b) Three spectrum subsections selected in the reflection spectrum of fiber-optic random grating; cross-correlation peak wavelength shift calibration results for temperature, strain, and refractive index [260].…”

Time-delay signature suppression in a chaotic semiconductor laser by fiber random grating induced random distributed feedback

“…Index modification spots with random spacing from 0 to 3.5μm were written along the fiber axis using a precision air bearing stage to translate the fiber and 50× microscope objective to focus the beam 29 . Around 50000 spots were made along the 10cm long standard single mode fiber (SMF).…”