Photonic generation of RF and microwave signal with relative frequency instability of ${10}^{-15}$

We demonstrate the ultra-stable frequency sources aiming to improve the short-time instability of primary frequency standards. These sources are realized by using photonic generation approach, and composed of ultra-stable lasers, optical-frequency-combs, optical signal detecting parts, and synthesizers. Preliminary evaluation shows that the sources produce fixed-frequency at 9.54(/9.63) GHz, 10 MHz, and tunable-frequency around 9.192 GHz with relative frequency instability of 10⁻¹⁵ for short terms. (paper)