Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor

Area of Science:

• Polymer optics
• Optical fiber sensors
• Materials science

Background:

• Polymer optical fiber Bragg gratings (POFBGs) are susceptible to environmental factors like humidity.
• Standard annealing of PMMA POFBGs often occurs at low humidity, impacting their long-term performance.
• Understanding humidity's effect on annealing is crucial for optimizing POFBG applications.

Purpose of the Study:

• To investigate the influence of humidity during annealing on PMMA-based mPOFBGs.
• To evaluate the impact of humidity-controlled annealing on the stability and humidity responsivity of mPOFBGs.
• To determine optimal annealing conditions for enhanced mPOFBG performance.

Main Methods:

• Fabrication of poly (methyl methacrylate) (PMMA) based microstructured polymer optical fiber Bragg gratings (mPOFBGs).
• Annealing of mPOFBGs under controlled high humidity and high temperature conditions.
• Characterization of mPOFBG performance, including humidity sensitivity, stability, and wavelength shift.

Main Results:

• High humidity annealing improves mPOFBG stability and humidity sensitivity compared to low humidity annealing.
• PMMA mPOFBGs annealed at high humidity exhibit higher, more linear humidity sensitivity with negligible hysteresis.
• Annealing at high humidity induced a significant blue-shift (>230 nm) in FBG wavelength without compromising grating strength.

Conclusions:

• High humidity annealing is a critical process for enhancing the performance of PMMA mPOFBGs.
• Optimized annealing conditions lead to more reliable and sensitive humidity sensors.
• This technique offers a pathway for developing advanced polymer optical fiber sensing devices.