Microwave Frequency Transfer via 11 km Fiber Link With Fiber-Loop Optical-Microwave Phase Detectors

We demonstrate a microwave frequency transfer experiment with a femtosecond pulse train via 11 km fiber link. The whole system is similar with the previous work conducted by researchers in KAIST, South Korea, but the fiber path length is nearly four times longer than the previous work. The fractional frequency instability between local and remote 7.5 GHz microwave oscillators in terms of Allan deviation reaches 2.3×10
^-14
at 1 s averaging time and goes down as τ
^-1
.