Influence of large signal modulation on photonic UWB generation based on electro-optic modulator

Various schemes based on electro-optic modulators have been reported to generate ultra-wideband (UWB) signals in the optical domain, but the availability of these methods always relies on small signal modulation. In this paper, the influence of large signal modulation on two typical schemes, representing two major categories of external-modulator-based photonic UWB generation schemes, is analytically and numerically studied. While the quasi single-sideband UWB (QSSB-UWB) pulse can maintain its shape, the Gaussian UWB (GUWB) generation scheme suffers serious modulation distortion when the phase modulation index is greater than π/6. The modulation distortion would have negative impact on the receiver sensitivity when the signal is sent to a correlation receiver.