Spatial differentiation of optical beams using phase-shifted Bragg grating Doskolovich, Leonid L. ; Bykov, Dmitry A. ; Bezus, Evgeni A. ; Soifer, Victor A. Abstract Publication: Optics Letters Pub Date: March 2014 DOI: 10.1364/OL.39.001278 Bibcode: 2014OptL...39.1278D