Towards integrated superconducting detectors on lithium niobate waveguides

TL;DR

This paper reports progress in integrating superconducting single-photon detectors, such as TESs and SNSPDs, onto lithium niobate waveguides, aiming for a unified platform for quantum light generation, manipulation, and detection.

Contribution

It demonstrates the integration of superconducting detectors with lithium niobate waveguides, including design, simulation, and initial characterization, advancing scalable quantum photonic technologies.

Findings

Successful coupling of evanescent fields into superconducting detectors

Room temperature characterization of absorption properties

Detectors respond effectively to flood illumination

Abstract

Superconducting detectors are now well-established tools for low-light optics, and in particular quantum optics, boasting high-efficiency, fast response and low noise. Similarly, lithium niobate is an important platform for integrated optics given its high second-order nonlinearity, used for high-speed electro-optic modulation and polarization conversion, as well as frequency conversion and sources of quantum light. Combining these technologies addresses the requirements for a single platform capable of generating, manipulating and measuring quantum light in many degrees of freedom, in a compact and potentially scalable manner. We will report on progress integrating tungsten transition-edge sensors (TESs) and amorphous tungsten silicide superconducting nanowire single-photon detectors (SNSPDs) on titanium in-diffused lithium niobate waveguides. The travelling-wave design couples the evanescent field from the waveguides into the superconducting absorber. We will report on simulations and measurements of the absorption, which we can characterize at room temperature prior to cooling down the devices. Independently, we show how the detectors respond to flood illumination, normally incident on the devices, demonstrating their functionality.