Time Stretching of UWB Radio Signals Using a Photonic Analogue-to-Digital Converter System Based on Wavelength Division Multiplexing

A photonic (Ph) analogue-to-digital (ADC) converter architecture using wavelength division multiplexing (WDM) technique is presented. This architecture is proposed as an alternative solution to the time division multiplexing (TDM) Ph-ADC used for ultra wideband radio signals monitoring purposes. The signal at the different points of the WDM Ph-ADC is analyzed in detail and both architectures are compared in terms of implementation complexity, signal-to-noise ratio (SNR) and nonlinear fiber impairments viewpoints. The main advantage of the WDM Ph-ADC architecture when compared with the TDM Ph-ADC is the possibility of having faster monitoring up-dates of the radio channel due to the higher pulse repetition rate allowed. This is achieved at the expense of system complexity increase. It is also concluded that the SNR of the WDM architecture is worse than in the TDM case and it presents lower tolerance to the fiber nonlinearity.