High-sensitivity strain sensor based on a helical-core long-period fiber grating

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensor Technology

Background:

• Fiber Bragg gratings (FBGs) and long-period fiber gratings (LPFGs) are widely used in sensing applications.
• Enhancing the sensitivity and reducing the size of fiber optic sensors are ongoing research challenges.

Purpose of the Study:

• To propose and experimentally investigate a highly sensitive strain sensor based on a helical-core long-period fiber grating (HC-LPFG).
• To explore the fabrication method and strain sensing performance of the novel HC-LPFG structure.

Main Methods:

• Fabrication of a helical-core structure in a single-mode fiber using a high-frequency CO2 laser and hydrogen-oxygen flame.
• Experimental investigation of the strain sensing characteristics of the fabricated HC-LPFG.
• Characterization of strain sensitivity and measuring range.

Main Results:

• The helical core structure leads to highly centralized refractive index modulation.
• The HC-LPFG sensor exhibits enhanced strain sensitivity and a reduced sensing area length of 2 mm.
• The maximum strain sensitivity achieved was -97 pm/µɛ within a measuring range of 0-400 µɛ.

Conclusions:

• The proposed HC-LPFG is a promising candidate for highly sensitive strain sensing applications.
• The fabrication technique is effective in creating a structure with improved sensing performance.
• The sensor's high sensitivity and compact size make it suitable for various industrial and scientific uses.