Abstract

Mode conversion in few-mode fibers has been excessively studied and utilized, e.g., for dispersion compensation [1]. For this purpose long-period gratings (LPG) have been permanently written into a fiber using UV or pulsed radiation. Recently, mode conversion has been demonstrated by transiently writing the grating structure into the fiber core via the optical Kerr effect with counter-propagating high power nanosecond pulses [2]. An energy transfer between two probe modes with an efficiency of about 50% could be measured, limited by the damage threshold of the fiber front facet. A femtosecond laser source offers the possibility to reach the necessary peak powers at by a factor of 1000 reduced pulse energy.

© 2013 IEEE