In another embodiment, an optical fiber is provided with {TAIL ~ reflective gratings} , {HEAD ~ each} of which are reflective at different wavelengths 
of
In another embodiment , an optical fiber is provided with { TAIL ~ reflective gratings } , { HEAD ~ each } of which are reflective at different wavelengths
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH