Attosecond-Resolution Er:Fiber-Based Optical Frequency Comb

Highly stable frequency-controlled optical frequency combs are key elements of many applications in time-frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbium-fiber-based optical frequency comb system. Its repetition rate is phase-stabilized to a continuous-wave laser with both an intra-cavity electro-optic modulator and a piezo-transducer; while the carrier-envelope-offset frequency is phase-locked to a radio-frequency signal generator by controlling the pump power. In-loop relative frequency stabilities of the comb are below 1 ×10^?16 at 1 s, and integrate down to low 10^?20 level at 10⁴ s. The corresponding timing uncertainties are 100–200 as over the full measurement range.