Speaker
Description
Nonlinear interferometry allows amplitude and phase information to be transferred between light that senses an object and light that is only detected. The technique exploits correlated photon beams generated via difference frequency generation or parametric fluorescence. When implemented non-degenerately, information can be passed between wavelengths to circumvent the technical and fundamental limitations of infrared (IR) detectors, such as thermal noise, enabling silicon-based sensors for applications spanning label-free biological and medical imaging to environmental monitoring.
Recent research has focused predominantly on a quantum mechanical variant known as imaging with undetected photons, where spontaneous parametric fluorescence occurs in phase-matched millimetre-scale nonlinear crystals and interferes by induced coherence without induced emission. Indistinguishable sets of photon pairs are generated at two instances, and the paths of respective wavelengths are overlapped. The absence of which-path information induces coherence; placing an object in the longer-wavelength path restores path knowledge and destroys interference at the shorter wavelength. Classical nonlinear interferometry achieves a similar outcome by stimulating the nonlinear emission, coherently transferring amplitude and phase across wavelengths, and offers advantages including an improved signal-to-noise ratio, greater interference coherence, and reduced reliance on highly nonlinear materials and phase matching.
The proposed talk presents the first demonstration of phase-matching-free sensing with undetected light using a nonlinear thin-film metasurface source. Within the interferometer, the resonant metasurface produces nonlinear emission via either four-wave mixing or harmonic generation under femtosecond-pulsed excitation, to achieve sensing in the near-IR and detection in the visible. The thin-film source results in bidirectional nonlinear emission that modifies the interferometer's operation, with consequences for both quantum and classical implementations. Engineering of the metasurface's optical properties provides control of the interferometric response not achievable with conventional nonlinear sources. Notably, phase sensitivity was found to scale linearly with harmonic order, revealing new functionality for such interferometers.
| I am the presenting author | Yes |
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