Long period grating refractive-index sensor: optimal design for single wavelength interrogation

Area of Science:

• Photonics
• Chemical Sensing
• Optical Sensors

Background:

• Long Period Gratings (LPGs) are optical fiber devices.
• Refractive index sensing is crucial for chemical analysis and process monitoring.
• Existing LPG sensors may lack optimized sensitivity for specific applications.

Purpose of the Study:

• To establish design criteria for optimizing LPG refractive-index sensors.
• To maximize sensor sensitivity by fixing the interrogation wavelength.
• To demonstrate the application of these criteria in practical sensing scenarios.

Main Methods:

• Developing theoretical design principles for LPG refractive-index sensors.
• Utilizing output power at a single interrogating wavelength as the key measurement parameter.
• Applying the design criteria to specific examples: sugar solution concentration and xylene in heptane detection.

Main Results:

• The study identifies specific design criteria for enhanced LPG sensor performance.
• Maximum sensitivity is achieved for a given refractive index range by fixing the interrogation wavelength.
• Successful demonstration of sensor design for practical applications was achieved.

Conclusions:

• The proposed design criteria enable the development of highly sensitive LPG-based refractive-index sensors.
• Fixed interrogation wavelength is a critical parameter for optimizing sensor sensitivity.
• The methodology is validated for real-world applications in chemical sensing.