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

TL;DR

This paper presents a low-loss, high-performance near-infrared lithium tantalate electro-optic modulator with low voltage requirements, high extinction ratio, and stable bias over time, suitable for integrated photonics.

Contribution

It demonstrates the first thin-film lithium tantalate Mach-Zehnder modulator at 737 nm with record low half-wave voltage and improved bias stability compared to lithium niobate devices.

Findings

Half-wave voltage-length product of 0.65 V·cm

Extinction ratio of 30 dB and optical loss of 5.3 dB

Bias drift of less than 2 dB over 16 minutes

Abstract

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$\cdot$cm, an extinction ratio of 30 dB, low optical loss of 5.3 dB, and a detector-limited bandwidth of 20 GHz. A small $<2$ dB DC bias drift relative to quadrature bias is measured over 16 minutes 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 0.5 dB/cm for a thin-film lithium tantalate waveguide is estimated at 638 nm using a fabricated ring resonator.