Phase conjugation with spatially incoherent light in complex media

Shaping light deep inside complex media such as biological tissue is critical to many research fields. Although the coherent control of scattered light via wavefront shaping has led to substantial advances in addressing this challenge, controlling light over extended or multiple targets without physical access to the inside of a medium remains elusive. Here we present a phase conjugation method for spatially incoherent light, which enables non-invasive light control based on incoherent emission from multiple target positions. Our method characterizes the scattering responses of hidden sources by retrieving mutually incoherent scattered fields from speckle patterns. By time-reversing scattered fluorescence with digital phase conjugation, we experimentally demonstrate focusing of light on individual and multiple targets. We also demonstrate maximum energy delivery to an extended target through a scattering medium by exploiting transmission eigenchannels. This paves the way to control light propagation in complex media using incoherent contrasts mechanisms. The non-invasive control of light based on incoherent emission from multiple target positions can be achieved by retrieving mutually incoherent scattered fields from speckle patterns, and then time-reversing scattered fluorescence with digital phase conjugation.

Automated summary

Shaping light deep inside complex media is crucial for various research fields, and controlling light without physical access to the inside of a medium has been a challenge. In this study, a phase conjugation method for spatially incoherent light is presented, enabling non-invasive light control based on incoherent emission from multiple target positions. The method retrieves mutually incoherent scattered fields from speckle patterns and time-reverses scattered fluorescence with digital phase conjugation. Various experimental demonstrations, including focusing light on individual and multiple targets, as well as delivering maximum energy to an extended target through a scattering medium, highlight the potential for controlling light propagation in complex media using incoherent contrasts mechanisms.