Full Duty Cycle, Frequency Doubled Triangular Microwave Waveform Generation Using a DP-MZM

A novel, triangular microwave waveform generating technique using a polarization-multiplex optoelectronic oscillator (OEO) is proposed. The proposed method uses fundamental ($f_{rf}$) and triple frequency tone ($f_{rf}^{\prime }=3f_{rf}$) signals to drive two sub-MZMs. Thus, carrier suppression modulation along two orthogonal polarization orientations is possible. Due to harmonic injection coupling, the two OEO oscillations can be precisely adjusted at 1:3. Due to tone polarization orthogonality, photo-detection yields no cross-beating terms. While adjusting the D.C. biases and modulation indices of the two sub-MZMs, the harmonic power ratio is suitably adjusted to create triangular microwave waveforms. The suggested OEO loop techniques avoid optical filters. Proof of concept experiments show that the proposed approach generates frequency-doubled triangle microwave waveforms with full-duty cycles.