Acousto-optic frequency shift modulators with acoustic and optic waveguides on X-cut lithium niobate substrates

Abstract

An optimal configuration of the waveguide acousto-optic frequency shift modulators on the X-cut lithium niobate substrates was analyzed. The conditions for efficient excitation of surface acoustic waves (SAW) and their interaction with the guided light in integrated optical structures were found. The influence of acoustic waveguide presence and interdigital transducer (IDT) geometry and material on the SAW resonance excitation was investigated. An acoustic waveguide configuration was proposed for increasing the TE-TM optical mode conversion efficiency. A low power (about 15 dBm) high frequency modulation signal was required for full TE-TM mode conversion in the proposed modulator configuration.