A study on tunable spectral frequency shift method with low phase noise

Frequency Scanning Multibeamforming Method Based on CFBG Photonic Microwave Oscillation

“…Te system design block diagram is shown in Figure 3. Te frequency source (inside the dashed boxed) is given by a CFBG-based two-loop photoelectric oscillator [8], which is mainly composed of a light source, a polarizer, a polarization combiner, single mode fbers, a photodiode, a radio frequency amplifer, a chirped grating, and a Mach-Zehnder external modulator (MZM) [9][10][11][12][13]. Te tuneable photoelectric oscillator can be tuned by using a chirped fber Bragg grating (CFBG) as a photonic flter to select the frequency of the oscillation mode [14][15][16].…”

“…A signal with frequency f is obtained at the output end. By reasonably designing τ 1 and τ 2 , the phase noise generated by the excitation signal at the ofset center frequency of 10 kHz can reach about − 140.5 dBc/Hz [8], compared to − 105 dBc/Hz with the conventional phaselocking technique. By adjusting the dispersion characteristic of the chirped grating, the oscillation frequency of the photon RF oscillator could be changed.…”

“…According to (8), the central frequency of photoelectric oscillation is determined by three parameters: wavelength of light source, grating dispersion, and bias voltage. Te dispersion characteristic of the grating can be adjusted to achieve large-bandwidth frequency tuning, thereby realizing large-scale scanning of the antenna beam.…”