Characterization of single-mode optical fiber filters

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Fiber Optics

Background:

• Narrowband highly reflecting filters are crucial for optical communication systems.
• Previous work demonstrated filter fabrication in single-mode step-index fibers using photoinduced effects.
• The core dopant, germanium dioxide (GeO2) in silica (SiO2) fibers, exhibits a photoinduced refractive-index change.

Purpose of the Study:

• To characterize optical fiber filters fabricated using photoinduced refractive-index changes.
• To develop a theoretical model for understanding filter performance.
• To determine key fiber parameters, including index change magnitude and its dependence on writing power.

Main Methods:

• Development of a theoretical model to describe the optical fiber filters.
• Experimental intercomparison to validate the theoretical model.
• Measurement of the photoinduced refractive-index change in GeO2-doped SiO2 fibers.

Main Results:

• Quantification of the magnitude of the photoinduced refractive-index change.
• Determination of the relationship between writing power and the refractive-index change.
• Validation of a theoretical model through experimental data.

Conclusions:

• The study successfully characterized optical fiber filters based on photoinduced index changes.
• The developed model and experimental findings provide insights into optimizing filter performance.
• Understanding the photoinduced index change is key for advancing highly reflecting fiber filter technology.