Self-Oscillating Triangular Pulse Generator Based on 90° Photonic-Assisted Phase Shifter

In this letter, we proposed and experimentally demonstrated a novel self-oscillating triangular pulse generator based on a 90 degrees photonic-assisted phase shifter. The fundamental harmonic is produced by the optoelectronic oscillation loop for generating triangular pulses. Meanwhile, the even-order harmonic suppression and the phase matching between odd-order harmonics are simultaneously realized by carrier phase-shifted double sideband modulation using a dual-parallel Mach-Zehnder modulator. Furthermore, the nine times amplitude ratio between the fundamental and third-order harmonics can be achieved by properly tuning the gain of the open oscillation loop. In the proof-of-concept experiment, self-oscillating triangular pulses with the repetition rates of 4 and 5.7 GHz are successfully generated with the phase noises of about -114 and -122 dBc/Hz at 10-kHz offset frequency. The corresponding root-mean-square errors between the generated and the ideal triangular waveforms are 5.9777e-4 and 6.0002e-4, respectively.