Phase Memory of Orbital Angular Momentum in Multiple Scattering Environment

Recent advancements in wavefront shaping techniques have facilitated the study of complex structured light's propagation with orbital angular momentum (OAM) within various media. The introduction of a spiral phase modulation to the Laguerre-Gaussian (LG) beam during its paraxial propagation is facilitated by the negative gradient of the medium's refractive index's temporal change, resulting in an accelerated retardation in OAM twist. This approach attains remarkable sensitivity to even the slightest variations in the medium's refractive index (10^(-6)). The phase memory of OAM is revealed as the ability of twisted light preserving initial helical phase even propagating through the turbid tissue-like multiple scattering medium. The results confirm fascinating opportunities of the exploiting OAM light in biomedical applications, e.g. such as non-invasive trans-cutaneous glucose diagnosis and optical communication through biological tissues and other optically dense media.
Comment: To be published in Nature Photonics