Linearized electrooptic directional coupler modulator in stoichiometric lithium niobate

This paper reports on a novel optical linearized directional coupler modulator in stoichiometric lithium niobate (SLN). The linearized design has important applications in analog and RF communications systems where fiber optic link performance depends critically on the spurious-free dynamic range of the modulator. Newly available SLN has several distinct advantages over the congruently grown crystals commonly used for high speed integrated optic devices, including higher electrooptic coefficient and better ferroelectric properties. The higher electrooptic coefficient yields lower drive voltage, while the enhanced ferroelectric properties enable better velocity-matched electrode structures using domain inverted waveguides. This paper addresses the operation of the linearized directional coupler design, and the critical advantages of the SLN substrate for implementing high-speed operation using velocity-matching.