A Simple Technique for Triangular Waveform Generation Based on a Dual-Polarization Modulator

A new microwave photonic topology for generating a triangular waveform is presented. The concept is based on incoherent summation of two intensity modulated optical signals to generate the first- and third-order harmonic frequency components with the same amplitude and phase as that of an ideal triangular waveform. The proposed triangular waveform generator has a very simple and low-cost structure as it only requires the Mach Zehnder modulator in a conventional fiber optic link to be replaced by an integrated dual-polarization modulator driven by two 90° phase difference RF signals. It also has a widely tunable repetition rate, low insertion loss, and a stable performance. Experimental results demonstrate a triangular waveform with a tunable microwave-frequency repetition rate and a root mean square error value of <0.049 when comparing with an ideal triangular waveform. The stability of the proposed triangular waveform generator is also examined experimentally.