Photothermal effects in fiber Bragg gratings

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Fiber Bragg gratings (FBGs) are fundamental components in optical fiber systems.
• Intrinsic broadband absorption in FBGs can lead to photothermal heating when exposed to guided light.

Purpose of the Study:

• To investigate the photothermal heating phenomenon in FBGs.
• To quantify the relationship between grating strength, absorption, and resonance shift.
• To explore methods for mitigating unwanted thermal effects.

Main Methods:

• Theoretical analysis of the intrinsic absorption term in FBGs.
• Experimental investigation of photothermal heating under varying light powers.
• Environmental influence assessment on grating heating.
• Development of a simple conductive model for thermal analysis.

Main Results:

• FBGs exhibit an intrinsic broadband absorption leading to photothermal heating.
• The magnitude of heating is dependent on grating strength and fiber core guided light.
• Resonance shifts occur due to the thermo-optic effect, even at low light powers.
• Environmental factors significantly influence the degree of photothermal heating.

Conclusions:

• Photothermal heating in FBGs is a significant factor affecting grating resonance.
• Understanding and controlling this heating is crucial for FBG-based applications.
• The developed model and mitigation strategies offer practical solutions for managing thermal effects in FBGs.