Prospects of multimode fibers and digital phase conjugation for optogenetics

Multimode fibers have drawn much attention, since they can convey multiple physical variables. However, the launched light generally excites multiple modes with different propagation velocities and mode mixing occurs. Multimode fibers behave as diffusing, turbid media and show speckles. Utilizing time reversibility of the scattering process exploited directly in digital optical phase conjugation (DOPC). One current hurdle of DOPC in biological applications is that the spatial information is transferred synchronously only. In this paper we present an asynchronous transmission through multimode fibers using DOPC. Our results carry potential for lensless endoscopic light delivery in optogenetics, which uses proteins to manipulate or measure of neural physiology. Optogenetic approaches allow activation or inhibition of genetically prescribed populations of neurons. It offers not only the ability to elucidate the functions of neural circuitry but also new approaches to the treatment of drug addiction, chronic pain, Parkinson disease, schizophrenia, epilepsy, autism and anxiety disorder as well as recovery of vision and auditory perception.