Pyroelectric Influence on Lithium Niobate During the Thermal Transition for Cryogenic Integrated Photonics

TL;DR

This paper investigates how pyroelectric charges generated during thermal transitions affect the optical properties of lithium niobate waveguides, which is crucial for cryogenic integrated quantum photonics applications.

Contribution

It provides the first detailed analysis of pyroelectric effects on lithium niobate during temperature changes between room temperature and cryogenic conditions.

Findings

Pyroelectric charge flow correlates with birefringence changes.

Effects are significant mainly above 100K.

Electrical and optical influences are characterized.

Abstract

Lithium niobate has emerged as a promising platform for integrated quantum optics, enabling efficient generation, manipulation, and detection of quantum states of light. However, integrating single-photon detectors requires cryogenic operating temperatures, since the best performing detectors are based on narrow superconducting wires. While previous studies have demonstrated the operation of quantum light sources and electro-optic modulators in LiNbO3 at cryogenic temperatures, the thermal transition between room temperature and cryogenic conditions introduces additional effects that can significantly influence device performance. In this paper, we investigate the generation of pyroelectric charges and their impact on the optical properties of lithium niobate waveguides when changing from room temperature to 25K, and vice versa. We measure the generated pyroelectric charge flow and correlate this with fast changes in the birefringence acquired through the Senarmont method. Both electrical and optical influence of the pyroelectric effect occurs predominantly at temperatures above 100K.