Tailored fabrication of a prospective acousto–optic crystal TiTe3O8 endowed with high performance

Abstract

A prospective acousto–optic (A/O) crystal TiTe₃O₈ endowed with superior thermal features and appreciable transparency is rationally developed by a tailored approach, namely TeO₂ (a material possessing outstanding A/O performance) in synergistic combination with TiO₂. Using the selected Li₂CO₃–TeO₂ fluxes, a high-quality and large-dimension single crystal of cubic TiTe₃O₈ is extracted through a high temperature top-seeded solution growth (TSSG) technique. Remarkably, TiTe₃O₈ contains a d⁰ transition metal cation, Ti⁴⁺, which is typically susceptible to second-order Jahn–Teller (SOJT) distortions, but surprisingly in a locally undistorted octahedral geometry. The high symmetry of TiTe₃O₈ makes it ideal for crystal processing and A/O device design. Notably, the tellurite crystal TiTe₃O₈ displaying an adequate A/O figure of merit is originally utilized to fabricate an A/O modulator that exhibits a high diffraction efficiency of 77%, which is competitive with the value reported for the TeO₂ crystal. Such a tailored design enriches the family of A/O materials and opens up a viable route toward exploiting controlled fabrication of potential A/O materials.