High-efficiency flip-chip coupling between single-mode fibers and LiNbO3 channel waveguides

Abstract

Coupling efficiencies of ≳70% have been consistently measured between single-mode fibers and LiNbO3 channel waveguides for TE and TM polarizations, using a Si V-groove/flip-chip arrangement. Tapered fibers in deep transverse grooves provide precise altitudinal alignment of the coupling fibers. These efficiencies are as high as those measured with a micropositioner and compare well with theoretical estimates of maximum coupling limited only by mode field distribution mismatch. Fiber/channel/fiber throughput losses of ∼3 dB and a polarization-independent interferometric waveguide modulator with fiber input and output are reported.