Tilted Fiber Bragg Grating Sensor with Graphene Oxide Coating for Humidity Sensing

Area of Science:

• Photonics
• Materials Science
• Sensor Technology

Background:

• Fiber Bragg gratings (FBGs) are widely used in sensing applications.
• Tilted fiber Bragg gratings (TFBGs) offer enhanced sensitivity due to cladding mode excitation.
• Graphene oxide coatings can modify the sensing properties of optical fibers.

Purpose of the Study:

• To develop and characterize a novel graphene oxide-coated TFBG humidity sensor.
• To investigate the effect of TFBG diameter on humidity sensing performance.
• To evaluate the sensitivity, linearity, and response of the proposed sensor.

Main Methods:

• Fabrication of TFBGs using the phase mask method.
• Etching of TFBGs to achieve different diameters (20, 35, 50, 55, 60 μm).
• Coating of etched TFBGs with graphene oxide using piezoelectric inkjet technology.
• Experimental characterization of humidity sensing performance.

Main Results:

• The TFBG etched to a 20 μm diameter exhibited the highest sensitivity.
• The sensor demonstrated a wavelength sensitivity of -0.01 nm/%RH.
• A high linearity of 0.996 was achieved.
• An increase in relative humidity led to a decrease in the sensor's refractive index and a shift in the TFBG cladding mode spectrum wavelength.

Conclusions:

• The proposed graphene oxide film TFBG humidity sensor is a promising candidate for effective relative humidity monitoring.
• The sensor's performance is significantly influenced by the TFBG diameter.
• The developed sensor offers a sensitive and linear response to humidity changes.