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

For the first time, to our knowledge, we demonstrate the experimental confirmation of a new vectorially based expression of the effective nonlinear coefficient gamma in bismuth suspended core fibers with core diameters of around 500 nm. The new expression predicts a significantly higher value of gamma than what is expected based on the standard expression. We confirm that there is a distinguishable difference between the standard and our new vectorially based gamma's, owing to the high index glass and subwavelength dimension of this fiber, and we show that the experimental result of gamma matches the new expression within the experimental error.