Photonic generation of triangular-shaped waveform signal with adjustable symmetrical coefficient

Abstract

ABSTRACTA configuration for triangular-shaped microwave signal generator is proposed and analysed. In the proposed model, a single-drive Mach–Zehnder modulator operated under the push–pull mode is firstly driven by a sinusoid signal. The lightwave is then split into two branches and converted by a balanced photodetector. According to the analysis, the output photocurrent contains infinite sinusoidal harmonics of the driven frequency. By adjusting three variables (modulation index, bias state and optical time delay), the power of the first three harmonics can be arbitrarily controlled. Such a property can be used in triangular-shaped microwave generation with adjustable symmetrical coefficient δ. The theory and discussion are proposed in this work. A fitting error η is defined to evaluate the waveform quality. With a defined η < 6%, the symmetrical coefficient can be adjusted within a range of 20% ≤ δ ≤ 80%.