Luminescence thermometry based on photon emitters in nanophotonic silicon waveguides

TL;DR

This paper introduces a luminescence-based thermometry technique using erbium emitters integrated into silicon nanophotonic waveguides, enabling high-resolution temperature measurements from room temperature to cryogenic levels.

Contribution

It presents a novel nanophotonic thermometry method that achieves high sensitivity and spatial resolution across a wide temperature range, surpassing traditional sensors.

Findings

Sensitivity of 0.22%/K at room temperature

Sensitivity increases to 420%/K at 2 K

Measurement precision down to 0.04 K at cryogenic temperatures

Abstract

The reliable measurement and accurate control of the temperature within nanophotonic devices is a key prerequisite for their application in both classical and quantum technologies. Established approaches use sensors that are attached in proximity to the components, which only offers a limited spatial resolution and thus impedes the measurement of local heating effects. Here, we therefore study an alternative temperature sensing technique that is based on measuring the luminescence of erbium emitters directly integrated into nanophotonic silicon waveguides. To cover the entire temperature range from 295 K to 2 K, we investigate two different approaches: The thermal activation of non-radiative decay channels for temperatures above 200 K and the thermal depopulation of spin- and crystal field levels at lower temperatures. The achieved sensitivity is 0.22(4) %/K at room temperature and increases up to 420(50) %/K at approximately 2 K. Within a few-minute measurement interval, we thus achieve a measurement precision that ranges from 0.04(1) K at the lowest studied temperature to 6(1) K at ambient conditions. In the future, the measurement time can be further reduced by optimizing the excitation pulse sequence and the fiber-to-chip coupling efficiency. Combining this with spatially selective implantation promises precise thermometry from ambient to cryogenic temperatures with a spatial resolution down to a few nanometers.