Trading Coupling Loss for Modulation Efficiency in Electrooptic Modulators.
01 January 1987
Phase modulators utilizing the electrooptic effect in LiNb0 (3) are most efficient if the waveguide, and hence the guided mode, is positioned as closely as possible to the modulation electrode which is located at the surface of the crystal. However, placing the guided wave near the crystal surface tends to deform its shape so that the coupling losses between the waveguide mode and an optical fiber is increased. In this paper we study the tradeoffs between coupling loss and modulation efficiency that result from moving the waveguide further below the crystal surface.