Measurement of the Static Structure Factor in a Paraxial Fluid of Light Using Bragg-like Spectroscopy
Piekarski, Clara and Liu, Wei and Steinhauer, Jeff and Giacobino, Elisabeth and Bramati, Alberto and Glorieux, Quentin

Phys. Rev. Lett. 127, 023401 (2021)

Phys. Rev. Lett. 127, 023401  (2021)

We implement Bragg-like spectroscopy in a paraxial fluid of light by imprinting analogues of short Bragg pulses on the photon fluid using wavefront shaping with a spatial light modulator. We report a measurement of the static structure factor, S(k), and we find a quantitative agreement with the prediction of the Feynman relation revealing indirectly the presence of pair-correlated particles in the fluid. Finally, we improve the resolution over previous methods and obtain the dispersion relation including a linear phononic regime for weakly interacting photons and low sound velocity.