Ultrawideband Impulse Radio Signal Generation Using a High-Speed Electrooptic Phase Modulator and a Fiber-Bragg-Grating-Based Frequency Discriminator

TLDR: In this article, the optical phase modulation to intensity modulation conversion is achieved by reflecting the phase modulated light at the slopes of the fiber Bragg grating (FBG) that serves as a frequency discriminator.

Abstract: We propose a novel approach to generating ultrawideband impulse radio signals in the optical domain. The proposed system consists of a laser source, an electrooptic phase modulator (EOPM), a fiber Bragg grating (FBG), and a photodetector (PD). The light source is phase modulated by an electrical Gaussian pulse train via the EOPM. The optical phase modulation to intensity modulation conversion is achieved by reflecting the phase modulated light at the slopes of the FBG that serves as a frequency discriminator. Electrical monocycle or doublet pulses are obtained at the output of the PD by locating the wavelength of the optical carrier at the linear or the quadrature slopes of the FBG reflection spectrum. The use of the proposed configuration to implement pulse polarity and pulse shape modulation in the optical domain is discussed. Experimental measurements in both temporal and frequency domains are presented