Multi-aperture three-dimensional beamforming

A system, comprising:

• a mode-locked laser source configured to provide a pulsed multi-frequency laser output signal having a spectrum with a plurality of comb lines, wherein one of the comb lines is a reference comb line, the comb lines forming a plurality of comb line pairs comprising the reference comb line and selected ones of the remaining comb lines;
• a plurality of N optical-electronic (OE) conversion circuits, each OE circuit corresponding on a one-to-one basis to the plurality of comb line pairs, wherein each OE circuit is configured to provide an electrical output signal having a frequency corresponding to a heterodyning of the comb lines in its corresponding comb line pair, and wherein the frequency for a first one of OE conversion circuits equals a pulse repetition frequency multiple (PRF) for the comb lines;
• a frequency for a second one of the OE conversion circuits equals 2*PRF, and so on such that a final Nth one of the OE conversion circuits has a frequency of N*PRF;
• a plurality of amplifiers corresponding on a one-to-one basis with the OE conversion circuits, each amplifier configured to amplify a version of the electrical output signal from its corresponding OE conversion circuit so as to provide an amplified output signal;
• an array of antennas corresponding to the plurality of amplifiers, each antenna configured to transmit the amplified output signal from the corresponding amplifier, whereby the array of antennas transmits a coherent and multi-frequency signal output pulse;
• a plurality of variable phase-shifters corresponding on a one-to-one basis with the OE conversion circuits, each variable phase-shifter configured to phase-shift the version of the electrical output signal provided to the amplifier corresponding to the phase-shifter's OE conversion circuit;
• and
• a controller configured to control the variable phase-shifters such that the multi-frequencies in the output pulse constructively add with each other at a desired range, azimuth, and elevation angle with respect to the array.