Without the phase matching, while {TAIL ~ the initial input light} has the desired shape, this shape is not retained throughout the traversal of {HEAD ~ the fiber} 
Without the phase matching , while { TAIL ~ the initial input light } has the desired shape , this shape is not retained throughout the traversal of { HEAD ~ the fiber }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD