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Photonic-Assisted Ultrawideband Pulse Generator With Tunable Notch Filtering Based on Polarization-to-Intensity Conversion

A photonic approach to generating ultrawideband (UWB) pulses with tunable band-rejection behavior and a chirp-free property, which is based on a nonlinear operated polarization-to-intensity converter, is proposed and demonstrated. As an initial phase shift of the incident light φ0 = π, a high-order UWB pulse fully satisfied the indoor mask regulated by the Federal Communications Commission was synthesized by a pair of polarity-inverted and doublet-like pulses at the output port of the polarization beam combiner. Moreover, the notch band will occur dynamically on the power spectra of the UWB signals from 3 to 16 GHz through adjusting the relative delay time between both doublet-like pulses from 333 to 62.5 ps due to the effect of microwave photonic filtering, which means that the spectrum-overlay-induced interference between UWB and other narrow-band communication systems could be real-time averted. In addition, the polarity switch of the synthesized UWB pulse could be implemented by adjusting angle α between the x-axis component of modulated light and the principal axis of the arm of transverse electric mode by the polarization controller.