Resolution-enhanced photonic quantization scheme based on weighted modulation transfer functions of lithium niobate...

Improving the bit resolution is a major challenge for the photonic quantization schemes based on the phase shifting of modulation transfer functions of Mach-Zehnder modulators (MZMs), since their quantization levels are limited to be 2N, where N is the number of employed modulators or optical channels. In this paper, we propose a novel, to the best of our knowledge, resolution-enhanced photonic quantization scheme, in which the input analog signals are quantized based on the intensity-weighted modulation transfer functions. By using N-wavelength sampling, 2N weighted modulation transfer functions and 2N+1 quantization levels can be obtained with only two MZMs. Hence, the proposed scheme can greatly improve the system bit resolution with a relatively simple configuration. A proof-of-concept experiment of a 17-level quantization system is carried out, which fully verifies the feasibility of the approach. Meanwhile, the performance degradation induced by the errors in the bias phase and the power deviation of sampling pulses is discussed. In addition, the performance limitation induced by the sampling source and dispersion-induced broadening is also investigated.