title: Spatial mode filters realized with multimode interference couplers.
abstract: Spatial mode filters based on multimode interference couplers (MMI's) that offer the possibility of splitting off antisymmetric from symmetric modes are presented, and realizations of these filters in InGaAsP/InP are demonstrated. Measured suppression of the antisymmetric first-order modes at the output for the symmetric mode is better than 18 dB. Such MMI's are useful for monolithically integrating mode filters with all-optical devices, which are controlled through an antisymmetric first-order mode. The filtering out of optical control signals is necessary for cascading all-optical devices. Another application is the improvement of on-off ratios in optical switches.
authors.forename: J
authors.initials: J
authors.lastname: Leuthold
authors.forename: R
authors.initials: R
authors.lastname: Hess
authors.forename: J
authors.initials: J
authors.lastname: Eckner
authors.forename: P A
authors.initials: PA
authors.lastname: Besse
authors.forename: H
authors.initials: H
authors.lastname: Melchior