由于电路时钟抖动和比较器弛豫等内禀属性的影响，传统的电子模数转换器已经不能满足高带宽数字信号处理的发展。模数转换主要包括采样、量化和编码。全光模数转换引入光子技术来对模拟电信号采样和量化，可以提高数字信号处理系统的性能，满足高速和高分辨率的需求，从而解决电子模数转换器的技术瓶颈问题。针对目前主要研究的全光模数方案，如泰勒方案、空间光干涉和偏振干涉的移相光量化方案、孤子自频移的方案、对称双波导长周期波导光栅和波导阵列光栅的方案等，介绍了其基本原理及实验方案，并对各种方案的特点进行了分析。

Due to the inherent timing jitter of the electronic clocking circuits and comparator ambiguity, the traditional electronic analog-to-digital conversion (ADC) cannot fulfill the development of high bandwidth digital signal processing. Analog-to-digital conversion consists of sampling, quantizing and coding. Introducing photonic technologies for sampling and quantization of the electrical analog signal, all-optical ADC can improve the performance of the digital signal processing system to achieve high sampling rate and high resolution. Hence, it solves the bottleneck problem of electronic ADC. The main recently developed all-optical analog-to-digital converters, such as those based on Taylor scheme, interferometric and polarization interference, phase-shifted optical quantization (PSOQ), soliton self-frequency shift, long-period waveguide grating (LPWG) and arrayed waveguide grating (AWG), are introduced. Meanwhile, the characteristics of different methods are analyzed.