800 nm WDM Interrogation System for Strain, Temperature, and Refractive Index Sensing Based on Tilted Fiber Bragg Grating

Abstract

Abstract-A low-cost high-resolution wavelength-division-multiplexing (WDM) interrogation system operating around 800 nm region with operational bandwidth up to 60 nm and resolution of 12.7 pm utilizing a tilted fiber Bragg grating (TFBG) and a CCDarray detector has been implemented. The system has been evaluated for interrogating fiber Bragg grating based strain, temperature sensors, giving sensitivities of 0.59 pm and 5.6 pm C, which are in good agreement with previously reported values. Furthermore, the system has been utilized to detect the refractive index change of sample liquids, demonstrating a capability of measuring index change as small as 10 5 . In addition, the vectorial expression of phase match condition and fabrication of TFBG have been discussed.Index Terms-Optical sensing, strain and temperature sensor, tilted fiber Bragg grating (TFBG), wavelength-division-multiplexing (WDM) interrogation system.

Applications of Fiber Bragg Grating Sensors in the Industry

“…On tilted Bragg gratings, the grating is in an angle concerning the optical axis resulting in the light being coupled outside of the fiber core, generating a change on the reflected wavelength and the bandwidth [18]. Generally, tilted Bragg gratings are used in optical interrogators as spectrometers [19].…”

Fiber Bragg Grating Sensors for Mainstream Industrial Processes

“…In tilted gratings, the grating is at an angle with respect to the optical axis causing the light to be coupled outside of the core of the fiber [22]. Generally tilted gratings are used in optical interrogators as spectrometers [23]. The first microstuctured FBG had the cladding diameter reduced around the FBG so that the evanescent wave could interact with the surrounding medium [24,25].…”

Power Tapping Function in Near Infra-Red Region Based on 45° Tilted Fiber Gratings

“…These drawbacks may be overcome by choosing relatively large angle TFGs and applying index matching gel on the fiber surface, respectively. Another work using small angle TFG reported by Rui et al is to use a 10˚-TFG to tap the light out from the fiber side for a sensing interrogation system [9]. However, due to total internal reflection effect, the light cannot be tapped out directly, but only after immersing the grating into oil with refractive index very close to the fiber cladding.…”