[IEEE 2008 Joint Conference of the Opto-Electronics and Communications Conference (OECC) and the Australian Conference on Optical Fibre Technology (ACOFT) - Sydney, Australia (2008.07.7-2008.07.10)] OECC/ACOFT 2008 - Joint Conference of the Opto-Electronics and Communications Conference and the Australian Conference on Optical Fibre Technology - Nonlinear empirical equations of (n2/Aeff) and n2 for various Ge-doped single mode optical fibers