A sub-volt near-IR lithium tantalate electro-optic modulator

We demonstrate a low-loss integrated electro-optic Mach–Zehnder modulator in thin-film lithium tantalate at 737 nm, featuring a low half-wave voltage-length product of 0.65 V cm, an extinction ratio of 30 dB, low optical loss of 5.3 dB, as well as a detector-limited and 3 dB bandwidth of 20 and 5 GHz, respectively. A small  dB DC bias drift relative to quadrature bias is measured over 16 min using 4.3 dBm of on-chip power in ambient conditions, which outperforms the 8 dB measured using a counterpart thin-film lithium niobate modulator. Finally, an optical loss coefficient of 0.6 and 0.5 dB/cm for a thin-film lithium tantalate waveguide is estimated at 789 and 638 nm using fabricated spirals and a ring resonator, respectively.