Tracking system by phase conjugation for laser energy transmission

We propose a new concept for a retro-directive tracking system applicable for communication and power transmission. In the proposed concept, the power transmitter utilizes a beacon emitted from the receiver to obtain information about its direction by conjugating its phase inside a nonlinear medium. Power is therefore transmitted back to the receiver by the phase conjugated beam. The power can be amplified by an array of phase conjugators which provides a large aperture so that the intensity can be increased on the receiver's photovoltaic panels compared to a single element. A system design provides the basic understanding of this setup and basic experiments are conducted with two Co-doped Sr _xBa _1-xNb _IIO ₆ (Co:SBN) crystals. We confirm the occurrence of interference of two beams that are generated by four wave mixing from a divergent signal beam. In areas of constructive interference, we could observe a higher intensity than the single non-interfering beams provides.