BRANCHED OPTICAL WAVEGUIDE, OPTICAL WAVEGUIDE SUBSTRATE AND OPTICAL MODULATOR

摘要

An optical waveguide is formed on a ferroelectric substrate having a thickness of 20 µm or less by means of dopant diffusion or ion exchange.  The optical waveguide is provided with a non-branched section (2a) wherein single mode propagation is performed, and a pair of branched sections which are branched from the non-branched section (2a).  Each of the branched sections is provided with a connecting section (7) extending from a branching end (10) and a multimode propagating section (8) continuous from the connecting section (7).  The width (m) of the multimode propagating section (8) is larger than the width (t) of the non-branched section.  The width (p) of the connecting section increases toward the multimode propagating section (8) from the non-branched section (2a).