Temperature-tunable photon-pair source for multiplexed time-resolved fluorescence on a nanophotonic platform.

Area of Science:

• Photonics
• Quantum Optics
• Materials Science

Background:

• Compact, scalable, and multiplexed fluorescence lifetime sensors are crucial for point-of-care diagnostics.
• Existing solutions often lack broad wavelength tuning or involve complex, non-miniaturized optical setups.
• On-chip entangled photon sources present a viable alternative due to temporal correlations, tunable spectra, and small footprints.

Purpose of the Study:

• To develop a temperature-tunable, visible quantum light source on a thin-film lithium niobate (TFLN) platform.
• To achieve a broad, continuous wavelength tuning range using a single waveguide.
• To demonstrate the suitability of TFLN for integrated photonic sensing applications.

Main Methods:

• Fabrication of a TFLN waveguide for quantum light generation.
• Utilizing type-I phase matching for efficient spontaneous parametric down-conversion.
• Characterization of the spectral tuning range and on-chip efficiency.

Main Results:

• Demonstrated a temperature-tunable visible quantum light source on TFLN.
• Achieved a continuous tuning range greater than one octave (564.5 nm to 1.494 µm) from a single waveguide.
• Measured an on-chip efficiency of (3.88±0.20)×10^9 pairs/s/mW, comparable to bulk lithium niobate sources.

Conclusions:

• The TFLN platform enables a highly tunable, efficient on-chip quantum light source.
• This technology is ideal for developing miniaturized, integrated photonic sensors.
• Potential applications include multiplexed fluorescence lifetime imaging and point-of-care diagnostics.