Abstract
Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines. Wavefront shaping and optical phase conjugation can focus light to a point. Transmission matrix method can control light on multiple output modes simultaneously. Here we report a non-invasive approach which enables three-dimension (3D) light control between two turbid layers. A digital optical phase conjugation mirror measured and conjugated the diffused wavefront, which originated from a quasi-point source on the front turbid layer and passed through the back turbid layer. And then, because of memory effect, the phase-conjugated wavefront could be used as a carrier wave to transport a pre-calculated wavefront through the back turbid layer. The pre-calculated wavefront could project a desired 3D light field inside the sample, which, in our experiments, consisted of two 220-grid ground glass plates spaced by a 20 mm distance. The controllable range of light, according to the memory effect, was calculated to be 80 mrad in solid angle and 16 mm on z-axis. Due to the 3D light control ability, our approach may find applications in photodynamic therapy and optogenetics. Besides, our approach can also be combined with ghost imaging or compressed sensing to achieve 3D imaging between turbid layers.
Highlights
Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines
Via memory effect, scanning of a light focus behind a turbid layer can be done on x-y plane[41,42] or along z-direction[43] by digitally superposing a linear or quadratic phase pattern on the optimized one displayed on spatial light modulator (SLM)
We demonstrated an approach combining memory effect and optical phase conjugation technique for 3D light control between two turbid layers in a completely non-invasive way with diffraction-limited resolution
Summary
Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines. Because of memory effect, the phase-conjugated wavefront could be used as a carrier wave to transport a pre-calculated wavefront through the back turbid layer. Guidestar-assisted methods[19], using either optical phase conjugation or wavefront shaping to suppress turbidity, can focus light through or into scattering media. We demonstrated an approach combining memory effect and optical phase conjugation technique for 3D light control between two turbid layers (in our case, two 220-grit ground glass plates spaced by a 20 mm distance) in a completely non-invasive way with diffraction-limited resolution. A direct application of our approach is to focus light into an optically transparent medium confined by turbid layers, such as crustaceans and eggs, without assistant of any real[47,48] or virtual[32,34,35] guidestars inside the medium, so our approach is completely non-invasive
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