Incoherent scattering losses in optical fiber Bragg gratings

Area of Science:

• Optics
• Materials Science
• Photonics

Background:

• Optical fibers and fiber Bragg gratings (FBGs) are crucial components in telecommunications and sensing.
• UV processing is a common method for fabricating FBGs, but can introduce imperfections.
• Scattered-light loss can degrade the performance of optical devices.

Purpose of the Study:

• To investigate scattered-light losses in UV-processed optical fibers and FBGs.
• To quantify broadband incoherent scattering loss near the Bragg wavelength.
• To understand the spatial distribution of grating elements contributing to scattering.

Main Methods:

• Measurements of scattered-light loss were performed for wavelengths near the Bragg wavelength.
• Broadband incoherent scattering loss was analyzed.
• The radial profile of scattered light was examined to infer grating localization.

Main Results:

• Scattered-light loss measurements ranged from 5 x 10(-5) to 0.2 dB/cm.
• Loss levels were found to depend on the specific fiber type and UV processing conditions.
• The radial scattering profile indicated that grating elements are primarily located within a few micrometers of the core-cladding interface.

Conclusions:

• UV processing of optical fibers and FBGs can result in significant scattered-light losses.
• Controlling processing conditions and fiber type is essential for minimizing scattering.
• The localization of grating elements near the core-cladding interface is a key factor in scattering behavior.