Skip to content
PaperFren

Nonlinear optics

Can we take 3D pictures with single mid-infrared photons?

Fang J, Huang K, Wu E, et al. · Light, science & applications · 2023

Open access · cc by · source: Europe PMC

Converting mid-infrared echoes into visible light with a femtosecond laser gate lets an ordinary silicon camera build detailed 3D images from extremely few photons.

Save to libraryView originalAsk PaperFrenStudy view

Study at a glance

Design
Other — Time-of-flight imaging: 3070 nm pulses illuminate a scene; returning photons are upconverted to 771 nm in a chirped-poled lithium niobate crystal by a delayed femtosecond pump and recorded on an EMCCD
N
No sample count; test objects were a coin under a silicon wafer, stacked silicon wafers and a ceramic goldfish
Population
Test objects imaged with a lab-built mid-infrared upconversion imaging system
Outcome
Depth and lateral resolution, volumetric reconstruction of layered samples, and image recovery at very low signal-to-noise

Structured fields used in claim comparison tables when every cited study has a complete layer.

Key findings

The system resolved a height difference of 30 micrometres on the coin through the wafer, with a lateral resolution of about 60 micrometres over a field roughly 2.5 cm wide. It located every internal interface of the stacked wafers, allowing the refractive index to be inferred from the axial offset. With the denoiser, the goldfish's 3D shape was recovered at a detected signal of only 0.05 photons per pixel per second, far below the background noise.

Methodology

The researchers illuminated objects with ultrashort mid-infrared pulses and collected the reflected light in a nonlinear crystal where a synchronized femtosecond pump pulse converted it to near-visible light only when both pulses overlapped in time. Scanning the pump delay sliced the scene by depth, and a megapixel silicon camera recorded each slice. They imaged a coin through a thick silicon wafer, two stacked wafers, and a ceramic goldfish at very low light, using a neighbour-product denoising algorithm for the dimmest data.

Limitations

This is a technique demonstration on a few static, hand-picked objects, not a systematic comparison with mid-infrared OCT on the same samples. Low-light imaging needed long exposures (seconds per frame across hundreds of depth slices), so it is slow for moving scenes. The denoiser assumes smooth, spatially correlated surfaces and could suppress real fine or isolated features; performance on scattering biological tissue was not tested.

How this study connects

Role on claims

Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.

  • SupportsSecond-harmonic generation and phase matchingconcept

    Frequency conversion lets cheap detectors see mid-infrared light.

    Nonlinear upconversion gated by a femtosecond laser converted mid-infrared echoes to visible light for a silicon camera, recovering 3D shape at 0.05 detected photons per pixel per second and resolving 30 um height steps.

    Evidence for the claim as stated.

Related papers in this topic

Same topic cluster — not a recommendation engine.