Wavefront shaping – light focusing through a scattering media


Wavefront shaping in scattering medium and multimode waveguides

A computer model of the process of multiple scattering of coherent optical beams by ordered ensembles of sub-wavelength dielectric particles has been created. Computer modeling has shown that a transverse shift of the illuminating beam by a distance of the order of the wavelength leads to complete decorrelation of the scattered field. This fact can be considered as confirmation of the “coupling” of the low-frequency component of the angular spectrum of the illuminating beam and the high-frequency components of the scattered field. Strong spatial non-invariance of the scattering function of a point in a diffuse medium is a necessary condition for the use of such media for light focusing.

Experimental focusing through a layer of titanium dioxide and zinc oxide has been implemented using a binary amplitude modulator, which allows achieving the diffraction limit. It has been shown that the critical issue that determines the quality of focusing is the dynamic range of measurements in the recording channel, not the number of degrees of freedom of the channel.

We are currently exploring the application of wavefront shaping in multi-mode optical fiber to precisely control light delivery in biomedical experiments. Also, we are experimenting with focusing light through thick samples that simulate biological tissues.

Installation for studying methods of focusing wavefront through a strongly scattering medium.

Focusing through a layer of beeswax. Sample thickness is 2.8 mm.

Selected publications:

Proc. SPIE , 2018, Vol. 10612, Art. No. 1061216

Proc. SPIE, 2019, Vol. 11078, Art. No. 1107827

Proc. SPIE, 2020, Vol. 11369, Art. No. 113691C

Proc. SPIE, 2021, Vol. 12126. – P.121260Z-1–121260Z-8

Wavefront shaping – light focusing through a scattering media