Small core optical waveguides are more nonlinear than expected: experimental confirmation

Area of Science:

• Nonlinear optics
• Optical fiber technology
• Materials science

Background:

• Standard nonlinear coefficient expressions may not fully capture behavior in novel fiber structures.
• Bismuth suspended core fibers offer unique nonlinear optical properties due to high index glass and subwavelength dimensions.

Purpose of the Study:

• To experimentally validate a new vectorially based expression for the effective nonlinear coefficient (gamma).
• To compare the predictions of the new expression with the standard expression for bismuth suspended core fibers.

Main Methods:

• Fabrication of bismuth suspended core fibers with core diameters around 500 nm.
• Experimental measurement of the effective nonlinear coefficient (gamma).
• Comparison of experimental data with predictions from both standard and vectorially based expressions.

Main Results:

• Experimental confirmation of the new vectorially based expression for gamma.
• The new expression predicts significantly higher gamma values compared to the standard expression.
• A distinguishable difference between standard and vectorially based gamma was observed, attributed to fiber properties.
• Experimental results closely matched the predictions of the new vectorially based expression within experimental error.

Conclusions:

• The vectorially based expression accurately describes the nonlinear coefficient in bismuth suspended core fibers.
• High index glass and subwavelength dimensions significantly influence the nonlinear behavior predicted by the new model.
• This finding advances the understanding and application of nonlinear effects in advanced optical fibers.