公开(公告)号：EP1092165A4

公开(公告)日：2005-06-22

申请号：EP99932157

申请日：1999-06-30

Applicant: CORNING INC

Inventor： BHATIA VIKRAM ,  COOK THOMAS A ,  MODAVIS ROBERT A ,  ROBSON CHRISTOPHER D

IPC: G02B6/13 ,  G02B5/18 ,  G02B6/02 ,  G02B6/122 ,  G02B6/34 ,  G02B27/58

CPC classification number: G02B6/02133 ,  G02B6/02085 ,  G02B6/02138 ,  G02B6/29347 ,  G02B27/58

Abstract: Filter gratings are formed in optical waveguides (50) having photosensitive cores by exposing the cores to actinic radiation in the form of interfering beams (38, 40) having peak intensities (72, 74) that are relatively displaced along an optical axis (64) of the waveguides. Each of the interfering beams has a single-lobed intensity profile and a degree of spatial coherence required to achieve a desired fringe contrast between the two relatively displaced beams. Index modulations in the photosensitive core match the illumination (interference) pattern of the radiation. The relative displacement of the interfering beams reduces side lobes of the gratings' spectral responses by leveling the average refractive index of the index modulations. A second exposure with the two beams but without the beams' interference effects further levels the average refractive index.