Remote transfer of a high-stability and ultralow-jitter timing signal.

Transfer of a high-stability and ultralow-jitter timing signal through a fiber network via a mode-locked fiber laser is demonstrated. With active cancellation of the fiber-transmission noise, the fractional instability for transfer of a radio-frequency signal through a 6.9- (4.5-) km round-trip installed (laboratory-based) fiber network is below 9(7) x 10(-15) tau(-1/2) for an averaging time tau > or = 1 s, limited by the noise floor of the frequency-counting system. The noise cancellation reduces the rms timing jitter, integrated over a bandwidth from 1 Hz to 100 kHz, to 37 (20) fs for the installed (laboratory-based) fiber network, representing what is to our knowledge the lowest reported jitter for transfer of a timing signal over kilometer-scale distances using an installed (laboratory-based) optical-fiber network.