Simultaneous strain and temperature sensing with photogenerated in-fiber gratings

Abstract

A new technique for simultaneous strain and temperature sensing is demonstrated. The approach employs two different types of photogenerated fiber grating, namely, a fiber Bragg grating and a fiber polarization-rocking filter. The method relies on the different dependencies of the fiber refractive index and birefringence on strain and temperature. Both of these measurands can be determined from the effect that they have on the resonant wavelength of each grating. The information is provided in the frequency domain, avoiding the problem of limited unambiguous signal range associated with the use of competing optical fiber interferometers.

A Review of Recent Developments in Fiber Optic Sensor Technology

“…Bragg gratings can, however, be used as the fiber sensing element in a host of other applications, and some interesting possibilities exist for the development of multiparameter sensor suites based on FBGs. Gratings are also currently being investigated for use in fiber laser sensors configurations, which can be configured for ultrahigh strain sensitivity applications.The current trends in grating sensor research are toward the use of modified or tailored gratings, such as chirped grating sensors [149,150], multimode gratings [151], other types of gratings, such as polarization rocking filters [152] and long period gratings [153,154], π -phase shifted devices [155], and "structured" gratings [156]. …”

Combined regenerated fibre Bragg gratings and Fabry-Perot etalons for dual strain and temperature sensing

“…Generally, in order to achieve accurate measurements, simultaneous measurement of temperature and strain is essential as the mechanical strain induced by thermal expansion can seriously influence the strain measurement accuracy [5][6][7][8][9][10][11][12][13]. Simultaneous measurement schemes based on different combinations of in-fibre Bragg grating (FBG) sensors and/or fibre-optic extrinsic Fabry-Perot interferometric (EFPI) sensors have been the subject of intense research in recent times because the thermal strain induced by temperature change for the strain sensor can be directly compensated using the temperature sensor nearby [5,[7][8][9]. However, many of these techniques lack the ability to endure high temperature operation.…”

Development of fiber Bragg gratings technology and their complex structures for sensing, telecommunications and microwave photonics applications

“…which were especially prepared for the FBGs inscription) to other types of fiber optic waveguides and components as polarization maintaining fibers [17] and tapers [18].…”