Temperature-Tunable Entangled Photon Source for Multiplexed Time-Resolved Fluorescence on a Nanophotonic Platform

TL;DR

This paper presents a temperature-tunable entangled photon source on thin-film lithium niobate, enabling broad wavelength tuning for compact, integrated fluorescence lifetime sensors and multiplexed spectroscopy.

Contribution

The authors develop a novel on-chip entangled photon source with over one octave wavelength tunability using type-I phase matching on TFLN, achieving high efficiency comparable to bulk sources.

Findings

Achieved >1 octave wavelength tuning (564.5 nm to 1.494 μm)

On-chip efficiency of (3.88±0.20)×10^9 pairs/s/mW

Demonstrated suitability for integrated photonic sensing applications

Abstract

Compact, scalable, and multiplexed fluorescence lifetime sensors are of great interest for point-of-care diagnostics. However, current solutions either lack broad-range wavelength-tuning capabilities or involve complex optical setups that hinder miniaturization. On-chip entangled photon sources offer a promising alternative for time-resolved spectroscopy with their strong temporal correlations, tunable spectral characteristics, and small footprints. Here, we develop a temperature-tunable, visible quantum light source on thin-film lithium niobate (TFLN) with a continuous tuning range greater than one octave, spanning 564.5~nm to 1.494~$\mu$m using only one waveguide. The tunability is enabled by utilizing type-I phase matching. We measured an on-chip efficiency of $(3.88\pm0.20)\times10^{9}$ pairs/s/mW, comparable to the most efficient type-0 bulk lithium niobate sources. These results show that the TFLN platform is ideal for on-chip integrated photonic and multiplexed lifetime imaging and sensing.