Photonic generation of triangular-shaped waveform with tunable symmetry based on a single-drive Mach-Zehnder modulator and differentiator

A novel and simple approach for photonic generation of triangular-shaped waveform with tunable symmetry is proposed and demonstrated experimentally. Firstly, triangular-shaped waveform with tunable symmetry is considered as a combination of sawtooth waveform, triangular waveform and reversed-sawtooth waveform. The generation of each of them is then accordingly implemented by a differentiator. Starting from a sinusoidal modulated signal, an integral waveform of triangular waveform and a dark parabola can be easily obtained, respectively, under different bias index and modulation index. From the perspective of envelope function operation, applying time-domain first-order differentiation to the former, triangular waveform
$(\delta=50\%)$
can be achieved. By differentiating to the latter, triangular-shaped waveform with tunable symmetry
$(\delta=44\%\sim45\%$
and
$\delta=56\%\sim57\%)$
can be obtained, respectively, under different time delay. Thus, triangular-shaped waveform with tunable symmetry
$(\delta=44\%\sim 45\%,\ 50\%,\ \delta=56\%\sim 57\%)$
are generated. In experiment, all of the expected results are successfully demonstrated and agree with the theoretical predictions well.