Focusing light deep inside living tissue has not been achieved despite its promise to play a central role in biomedical imaging, optical manipulation and therapy. To address this challenge, internal-guide-star-based wavefront engineering techniques—for example, time-reversed ultrasonically encoded (TRUE) optical focusing—were developed. The speeds of these techniques, however, were limited to no greater than 1 Hz, preventing them from in vivo applications. Here we improve the speed of optical focusing deep inside scattering media by two orders of magnitude, and focus diffuse light inside a dynamic scattering medium having a speckle correlation time as short as 5.6 ms, typical of living tissue. By imaging a target, we demonstrate the first focusing of diffuse light inside a dynamic scattering medium containing living tissue. Since the achieved focusing speed approaches the tissue decorrelation rate, this work is an important step towards in vivo deep tissue noninvasive optical imaging, optogenetics and photodynamic therapy.

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Acousto-optic imaging is based on ultrasound modulation of multiply scattered light in thick media. We experimentally demonstrate the possibility to perform a self-adaptive wavefront holographic detection at 790nm, within the optical therapeutic window where absorption of biological tissues is minimized. A high-gain Te-doped Sn(2)P(2)S(6) crystal is used for this purpose. Optical absorbing objects embedded within a thick scattering phantom are imaged by use of pulsed ultrasound to get a dynamic millimetric axial resolution. Our technique represents an interesting approach for breast cancer detection.

The photorefractive properties of Sn 2 P 2 S 6 crystals doped with Te and Sb in the near-infrared wavelength range up to 1064 nm are reported. The main photorefractive parameters, i.e., two-wave mixing gain, effective electrooptic coefficient, diffusion length, concentration of traps, and response time, are compared with conventional nominally pure Sn 2 P 2 S 6 . Te-doped Sn 2 P 2 S 6 shows the fastest response with the smallest decrease of the photorefractive efficiency with increasing wavelength in the near infrared. Sb doping, on the other hand, inhibits photorefraction in the near infrared. Sn 2 P 2 S 6 :Te and Sn 2 P 2 S 6 :Sb crystals both show a high two-wave mixing gain ⌫ at 633 nm, and 10 and 20 cm −1 . Te-doped Sn 2 P 2 S 6 shows a photorefractive gain of 4.5 cm −1 at 1064 nm. Response times at 1064 nm of 20 ms have been measured for the intensity 6 W/cm 2 , which is 2 orders of magnitude shorter than in Rh-doped BaTiO 3 .