Abstract

Frequency-shifted feedback was recently used to synchronize the beat note between the two modes of a dual-frequency laser with the radiofrequency emitted by a local microwave oscillator. This technique allows one to obtain an optically-carried RF clock signal that can find applications in microwave photonics. Two regimes of synchronization are then found [1]. When the frequency difference ∆ν between the two oscillators is smaller than a frequency f_A determined by the feedback amount, the two oscillators are phase-locked, leading to a constant relative phase ϕ. Then, a regime of frequency locking without phase locking appears. This regime, also called bounded phase [2,3], extends the frequency synchronization beyond f_A up to a frequency f_B. Finally, when ∆ν is larger than f_B, the two oscillators are not synchronized, resulting in an unbounded drifting phase. Here, we experimentally characterize the three regimes and compare the results to numerical simulations.

© 2013 IEEE