Space diversity receiver for optical communications

A non-line of sight optical communication system, comprising:

• a transmitter sending an information bearing light beam through the atmosphere at an elevated angle;
• a receiving unit, receiving a light scattered on atmospheric inhomogeneities along the beam propagation;
• the receiving unit including at least a first combiner for the receiving beam, comprising
• 2M input waveguides, where M is an integer≧1, receiving portions of the optical beam;
• the waveguides forming an array positioned perpendicular to the optical beam propagation direction;
• (2M−1) directional couplers;
• each coupler is formed by two waveguides, coming in and out of the coupler;
• a first output waveguide from each coupler forming an input waveguide for a subsequent coupler from (2M−1) couplers;
• a final output waveguide from the last coupler forming a final output beam of the device;
• and wherein a portion of the final output beam is used in control means changing input phases in at least one input waveguide of each coupler to maximize the final output beam power.

A method of non-line of sight data transmission, comprising:

• sending an information bearing light beam through the atmosphere at an elevated angle;
• receiving first portions of a light scattered on atmospheric inhomogeneities along the beam propagation by at least a first optical combiner, comprising 2M input waveguides, where M is integer≧1;
• the input waveguides forming a one-dimensional array positioned perpendicular to the beam propagation direction;
• coupling each pair of adjacent waveguides;
• each coupler is formed by two waveguides, coming in and out of the coupler;
• in each coupler the output of a first output waveguide forming an input waveguide for a subsequent coupler from (2M−1) couplers;
• an output waveguide from the last coupler forming a final output beam of the device;
• and
• wherein the control means changing the input phases to maximize the final output beam power;
• and
• wherein the control means changing the coupling ratios to maximize the final output beam power.