Optical focusing through biological tissue and tissue-mimicking phantoms up to 9.6 centimeters thick with digital optical phase conjugation

Optical phase conjugation (OPC) based wavefront shaping techniques focus light through or within scattering media, which is critically important for deep-tissue optical imaging, manipulation, and therapy. However, to date, the sample thicknesses used in wavefront shaping experiments have been limited to only a few millimeters or several transport mean free paths. Here, by using a long-coherence-length laser and an optimized digital OPC system that efficiently delivers light power, we focused 532 nm light through tissue-mimicking phantoms up to 9.6 cm thick, as well as through ex vivo chicken breast tissue up to 2.5 cm thick.