Differentially Encoded Photonic Analog-to-Digital Conversion Based on Phase Modulation and Interferometric Demodulation

We propose a novel approach to realizing photonic analog-to-digital conversion in a system with a phase modulator (PM) and a delay-line interferometer (DLI). The phase modulation and interferometric demodulation techniques are employed to realize quantization and encoding. In the system, the phase-modulated signal is optically sampled by a multiwavelength pulsed source and the phase-shifted transfer functions of the DLI under different wavelengths are used for encoding. In the approach, the differential signal, but not the original analog signal, is encoded, which increases the equivalent number of bits. In addition, the balanced detection technique can be incorporated into the system to alleviate the influences of amplitude and timing jitter.