Nonlinearity in bent optical fibers

Area of Science:

• Nonlinear optics
• Materials science
• Optical engineering

Background:

• Optical fibers exhibit nonlinear optical properties crucial for advanced applications.
• Bending optical fibers can induce stress, potentially altering these nonlinear parameters.
• Understanding these variations is key to predicting fiber performance under strain.

Purpose of the Study:

• To present an interferometric method for studying induced variations in nonlinear parameters of bent optical fibers.
• To investigate the asymmetric changes in third-order susceptibility (χ((3))) and nonlinear refractive index (n(2)) with fiber curvature.
• To demonstrate the high spatial and index resolution of the developed measurement technique.

Main Methods:

• Utilized an interferometric approach to probe nonlinear optical properties.
• Investigated single-mode optical fibers at standard wavelengths (1300 nm and 1550 nm).
• Applied varying radii of curvature ranging from 5 mm to 11 mm.

Main Results:

• Observed and calculated asymmetric variation profiles for χ((3)) and n(2) with curvature.
• Quantified nonlinear parameters in both the cladding and core under tensile and compressive stress.
• Reported specific values for χ((3)) and n(2) at different wavelengths and radii of curvature, highlighting asymmetry.

Conclusions:

• The interferometric method effectively reveals asymmetric variations in nonlinear parameters of bent optical fibers.
• The nonlinear response of the fiber material's Young's modulus influences these parameter changes.
• The technique offers high spatial and index resolution for characterizing optical fibers under stress.