Lithium niobate modulator from room temperature to cryogenic conditions

Electro-optical (EO) modulators with lithium niobate waveguide are essential components in modern communication systems and quantum photonic applications. With the advancement of cryogenic photonic integrated circuits, they have become critical for cryogenic photonic readout, enabling massive data transfer from superconducting electronics to room temperature environments. Here, we demonstrate an integrated modulator based on a thin-film lithium niobate platform. The designed modulator achieves a tuning efficiency (V_π · L) of 3.84 V·cm at room temperature. To investigate the relationship between half-wave voltage and temperature, we gradually reduce the temperature and observe a 70% increase in V_π at 8 K. Additionally, we report on the photorefractive effect at different temperatures. High-speed data transmission is successfully demonstrated at 8.5 K, showing the modulator’s capability to operate across a wide temperature range, from room temperature to cryogenic conditions.