METHOD OF AND DEVICE FOR MEASURING THE NONLINEAR REFRACTIVE INDEX IN A SINGLE MODE OPTICAL FIBRE

摘要

A method and apparatus for determining the non-linear refractive index coefficient for an optical fibre.The method comprising sending a train of transform-limitedoptical pulses with wavelength close to the zero-dispersionwavelength of the fibre and high and variable peak power,so as to give rise to self-phase modulation, into a fibre;measuring the spectral broadening of the signal exiting thefibre for a number of values of the peak power of thepulses; and obtaining the nonlinear refractive index fromthe angular coefficient of the straight line representingspectral broadening versus peak power. The apparatus forperforming the method includes means for determining thespectral broadening of the pulses as the peak power variesand means for obtaining the nonlinear refractive index fromthe angular coefficient of the straight line representingspectral broadening versus peak power.