40-GHz Photonic Synthesizer Using a Dual-Polarization Microlaser

An optically carried microwave synthesis working at 40 GHz is demonstrated by using a two-frequency solid-state microchip laser inserted as a voltage-controlled oscillator inside a digital phase-locked loop. We report an in-loop relative frequency stability better than 2.5 × 10
^-11
. The capabilities of the synthesis are illustrated with different frequency sweeping formats.