Multimode Interference Couplers for the Conversion and Combining of Zero- and First-Order Modes Leuthold, Juerg ; Eckner, Juerg ; Gamper, Emil ; Besse, Pierre A. ; Melchior, Hans Abstract Publication: Journal of Lightwave Technology Pub Date: July 1998 DOI: 10.1109/50.701401 Bibcode: 1998JLwT...16.1228L