Very high-speed Analog-to-Digital Converters (ADCs) are key components in ultra-wide bandwidth communication and radar systems. New progress of digital processors has made possible processing of 100-Gb/s data. Nevertheless, electronic ADCs are showing a lack in their sampling rate largely due to the timing jitter of actual electronic sampling system. Interleaving hundreds of elemental flash ADCs has permitted to reach approximately 60 Gs/s data conversion but this technique is very complex since it requires a great number of ADCs, numerous clock distribution circuits and additional ones to improve bandwidth and to reduce interleaving errors. One of the most interesting solutions to overcome this jitter problem is to use All-Optical ADCs ( AOADCs ). We are currently working on an AOADC concept based on an electro-optic deflector. This latter is fabricated using electro-optic (E-O) polymer and takes advantage, on one hand, of very low jitters offered by optical laser pulses (state-of-the-art mode-locked lasers reveal performances of 20 attosecond jitter), and on the other hand, good velocity matching between microwaves and optical waves in polymeric materials. The deflector works on the principle of the Pockel effect. An electro-optic core is situated between coupled micro-strip RF driving electrodes. Input analog RF signal applied onto them modifies the refractive index of the core and consequently the propagation direction of the leaky optical beam. By combining an adequate design of the optical waveguide with a high-index superstrate, the evanescent leaky beam is converted into a propagating beam which deflection angle depends on applied RF voltage onto the electrodes. In a previous work [5] the angular distribution of the 2D far field within the superstrate has been calculated using the Fast Fourier Transform. It allowed to determine the ENOB of the AOADC knowing the angular divergence, but the lack of data on the near field was a barrier in the design of the optical collector allowing this deflected beam to be detected by a photodetector array.This paper reports on calculation of the near field of the deflected beam using BPM method. The purpose is to calculate the 3D near field profile in order to obtain its phase and amplitude distributions that will be used as input data for the optical collector design. This study also reveals the behavior of the beam at the upper part of the superstrate, where ripple appears. The impact of those ripples has been calculated to investigate their influence on the collector.