An Approach to Optical Generation and Distribution of Binary Phase Coded Direct Sequence Ultra-Wideband Signals

A novel technique to generate binary phase-coded, direct sequence UWB signals in the optical domain is proposed and demonstrated. In the proposed system, a laser array is phase modulated by a Gaussian pulse, which is then sent to a multi-channel frequency discriminator, to generate a UWB monocycle or doublet pulse sequence with a pre-determined phase code pattern. By tuning the wavelengths of the laser array, the generated pulse shape and code pattern can be changed. The key device in the system is the multi-channel dispersion fiber Bragg grating (FBG), which functions, in combination with a dispersive fiber, as a multi-channel frequency discriminator with a step-increased group delay response. It ensures the generation of a UWB sequence with equal time spacing between the chips. The proposed scheme is experimentally demonstrated.