Optical phased arrays

A method of coherent detection and ranging, the method comprising:

• (A) evanescently coupling a plurality of phase-shifted coherent optical beams from a first plurality of cascaded phase shifters to a first plurality of antenna elements;
• (B) emitting the plurality of phase-shifted coherent optical beams from the first plurality of antenna elements so as to illuminate at least one surface with a far-field radiation pattern;
• (C) receiving radiation reflected and/or scattered by the at least one surface with a second plurality of antenna elements;
• (D) evanescently coupling the radiation from the second plurality of antenna elements to a second plurality of cascaded phase shifters;
• and
• (E) phase-delaying respective portions of the radiation with second plurality of cascaded phase shifters so as to form a return signal representative of the at least one surface.

A lidar comprising:

• a substrate;
• a tunable light source, in mechanical association with the substrate, to generate a frequency-modulated coherent optical beam;
• a first tapped delay line, formed in or on the substrate in optical communication with the tunable light source, to produce a plurality of coherent phase-shifted optical beams from the frequency-modulated coherent optical beam;
• a first array of antenna elements, formed in or on the substrate in evanescent communication with the first tapped delay line, to emit the plurality of phase-shifted coherent optical beams so as to form a far-field radiation pattern;
• a second plurality of antenna elements, formed in or on the substrate, to receive radiation reflected and/or scattered by at least one surface illuminated by the far-field radiation pattern;
• a second tapped delay line, formed in or on the substrate in evanescent communication with the second plurality of antenna elements, to phase-delay respective portions of the radiation detected by the second plurality of antenna elements so as to form a return signal representative of the at least one surface illuminated of the far-field radiation pattern;
• and
• a detector, formed in or on the substrate in optical communication with the second tapped delay line and the tunable light source, to detect interference of the return signal and a copy of the frequency-modulate coherent optical beam.