Fig. 1. Diagram of the demonstrated all-fiber-photonics-based X-band synthesizer. AOFS, acousto-optic frequency shifter; FBG, fiber Bragg grating; FRM, Faraday rotating mirror; BPD, balanced photodetector; BPF, bandpass filter; LPF, low-pass filter.

Fig. 2. Absolute SSB phase noise and integrated timing jitter of the generated microwave signals. Curve (i) [black], phase noise of the 10 GHz DRO locked to the stabilized MLL. Curve (ii) [pink], phase noise floor of the used PNA at 10 GHz carrier frequency. Curve (iii) [blue], projected phase noise at 10 GHz by an optical-domain measurement. Curve (iv) [light purple], residual noise floor of FLOM-PD synchronization. Curve (v) [green], phase noise of the 9 and 11 GHz signals from the synthesizer output. Note that the red area indicates the phase noise range of the DDS output from 10 MHz (bottom red curve) to 1 GHz (top red curve). As a result, the phase noise of the synthesizer output (9–11 GHz) lies between curve (i) (10 GHz) and curve (v) (9 and 11 GHz), indicated as the diagonal patterned area. Curve (vi), integrated timing jitter for curve (i). Curve (vii), integrated timing jitter for curve (iii). Curve (viii), integrated timing jitter for curve (v) at 9 GHz.

Fig. 3. Phase error during frequency transition and settling process. Inset, waveform captured by the oscilloscope at the moment that frequencies transit and settle.

Fig. 4. Spur suppression ratio for 50 MHz–1 GHz output range in 1.25 GHz span. Inset, the spectrum for 500 MHz output.

Fig. 5. (a) Recovered instantaneous frequency of LFM signal increased from 10.5 to 11 GHz in 500 ns. (b) Autocorrelation of the LFM signal in (a).