(a) a photonic oscillator comprising a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier;

(b) an optical heterodyne synthesizer, the optical heterodyne synthesizer including first and second phase-locked lasers, the first laser feeding the optical carrier to the multi-tone optical comb generator and the second laser comprising a wavelength-tunable single tone laser whose output light provides a frequency translation reference; and

(c) a photodetector for heterodyning the frequency translation reference with the series of RF comb lines on the optical carrier generated by the photonic oscillator to generate an agile spread spectrum RF waveform;

wherein the photonic oscillator further comprises multiple loops including:

(i) a first optical delay line in a first loop for spacing a comb generated by the multi-tone optical comb generator;

(ii) a second optical delay in a second loop line for noise reduction, the second delay line being longer than the first optical delay line;

(iii) at least one photodetector connected to the first and second delay lines; and

(iv) an optical intensity modulator in a loop portion common to the first and second loops for driving the first and second optical delay lines.