Full-duty triangular pulse generation based on a polarization-multiplexing dual-drive Mach-Zehnder modulator

Abstract

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.

Observation of parity-time symmetry in microwave photonics

“…The DPMZM consists of two sub MZMs lying on each arm of the modulator. A polarization rotator is added to an arm to rotate the state-of-polarization of the optical signal 38 , 39 . A short single-mode fiber attached to the DPMZM acts as an energy storage medium.…”

Impact of Bandwidth on Range Resolution of Multiple Targets Using Photonic Radar

“…To enable multiple targets detection, polarization division multiplexing (PDM) in conjugation with wavelength division multiplexing (WDM) has been employed in the proposed Photonic radar sensor system. The PDM inclusion ensures enormous working frequency range and better sturdiness in the operation of Photonic radar system as neither precise high modulation index nor optical filtering is required [26], [27]. The system is also simulated for range resolution using different frequency bandwidths under adverse weather conditions and results were compared as effected of varying bandwidth on the range resolution of Photonic radar.…”

Photonic Generation of Triangular-Shaped Waveform With Tunable Symmetry Factor Based on Two Single-Drive Mach-Zehnder Modulator

“…The main thought of this method is to utilize external modulation to make optical intensity of generated signal approximately equal to the Fourier series expansion of ideal triangular waveform. A large number of schemes for symmetrical triangular waveform generation based on this method have been reported in the past decades, such as based on a single-drive Mach-Zehnder Modulator [7], modulator combined with dispersive fiber [8], [9], modulator combined with filter [10], [11], modulator combined with polarization devices [12], [13], stimulated Brillouin scattering [14] and optoelectronic oscillator [15]- [16]. Based on external modulation, the researchers also have proposed many schemes for generating sawtooth waveform [17]- [19].…”