Graphene-oxide Coated on Fiber Bragg Grating for Temperature Sensor

The rapid development and deployment of optical sensors have brought fibre Bragg grating (FBG) as a renowned optical sensor which acquired high sensitivity, fast response to the measurement changes and small in size. However, the implementation of bare FBG sensor could be further enhanced to give significant impact in terms of sensitivity without any alteration on the effective refractive index and the grating period. Therefore, a low cost and high temperature sensitivity of fiber Bragg grating (FBG) sensor coated with graphene oxide (GO) is designed and constructed. The FBG is synthesized with GO by implementing dip coating technique. Then, the bare and coated FBG sensor is tested by applying heat at the grating region of the FBG. The output of the experiment is displayed on the optical spectrum analyzer (OSA) in terms of power (dBm) and wavelength (nm). The performances of the FBG sensors have been evaluated by comparing the temperature sensitivity. The GO-coated FBG recorded better temperature sensitivity of 16.0 pm/°C compared to the bare FBG with sensitivity of 15.0 pm/°C. The results indicate the ability of graphene oxide to improve the Bragg wavelength shift by the combined effect of effective refractive index and grating period that are influenced by the changes of temperature. GO-coated FBG also exhibits better linear fit of 99.1%, which specifies the consistency of the wavelength shift reading as temperature increased and low limit of detection (LOD) compared to the bare FBG as the minimum value of LOD signifies the effectiveness of the sensor.