LAUSR

Abstract We theoretically and numerically investigate the modulation efficiencies of integrated electro-optic (EO) modulators based on ferroelectric crystals with the point symmetry of orthorhombic mm2. An analytical expression describing the index-ellipsoid under the EO effect is derived, where all 5 non-zero linear EO coefficients of mm2-crystals are considered. As practical candidates for integrated EO platform, three mm2-crystals (KNbO 3 , KTiOPO 4 , and Ba 2 NaNb 5 O 15 ) that are well-established and commercially available are chosen for numerical simulations. The refractive-index (RI) changes caused by an external electric field applied to each crystal with an arbitrary direction are analyzed in detail for the given optical polarization states of input light wave. For each crystal, the modulation efficiency is evaluated in terms of the half-wave voltage required for a π-phase shift of input wave, which is compared with the established counterpart based on LiNbO 3 . The results indicate that higher modulation efficiencies are achievable in the two schemes using KNbO 3 and Ba 2 NaNb 5 O 15 than those for other cases, meaning that either lower power-consuming or larger beam-window integrated EO devices are feasible.