Full duty triangular pulse generation based on a polarization multiplexing dual drive Mach Zehnder modulator.
A simple and flexible photonic approach to generating a triangular microwave waveform using a single integrated polarization multiplexing dual drive Mach Zehnder modulator (PM DMZM) and a polarizer is proposed and demonstrated, which needs no specific large modulation indices or an optical filter. In the proposed method, one sub Mach Zehnder modulator (MZM) in the PM DMZM is driven by a fundamental frequency, which generates an optical signal composed of an optical carrier and a 1st order sideband along one polarization direction; and the other sub MZM is driven by a frequency tripled signal, generating an optical carrier and a 1st order sideband along the orthogonal polarization direction. By adjusting the polarization direction of the polarizer following the PM DMZM, which changes the power ratio of the two sidebands, optical intensity with expression corresponding to the Fourier expansion of a triangular shaped waveform is obtained. Different from the previously reported approaches, neither specific large modulation index nor optical filtering is required, which guarantees a large operational frequency range and improved robustness. A proof of concept experiment is carried out. 5 GHz triangular shaped waveform signals are successfully generated with different modulation indices.
Optics express