High-gain and high-speed wavefront shaping through scattering media

Wavefront shaping (WFS) is emerging as a promising tool for controlling and focusing light in complex scattering media. The shaping system's speed, the energy gain of the corrected wavefronts and the control degrees of freedom are the most important metrics for WFS, especially for highly scattering and dynamic samples. Despite recent advances, current methods suffer from trade-offs that limit satisfactory performance to only one or two of these metrics. Here we report a WFS technique that simultaneously achieves high speed, high energy gain and high control degrees of freedom. By combining photorefractive crystal-based analogue optical phase conjugation and stimulated emission light amplification, our technique achieves an energy gain approaching unity; that is, more than three orders of magnitude larger than conventional analogue optical phase conjugation. The response time of ~10 μs with about 106 control modes corresponds to an average mode time of about 0.01 ns per mode, which is more than 50 times quicker than some of the fastest WFS systems so far. We anticipate that this technique will be instrumental in overcoming the optical diffusion limit in photonics and translate WFS techniques to real-world applications.