中心博士生秦睿恒同学的工作——Optical sample-and-hold for clock skew immunity in high-speed channel-interleaved photonic analog-to-digital converters（基于光学采样保持的高速时间交织型光子模数转换器时钟偏移抑制技术）的相关成果最近被Optics Express期刊接收，该工作得到了国家自然科学基金（T2225023, 62205202, 62205203）以及上海市青年科技英才扬帆计划（No. 22YF1420200）的部分资助。
现有的高速信道交错光子模数转换器（PADC）在大规模、高分辨率设计中受到时钟同步精度的严重制约，导致多通道间由时钟偏移引起的时序误差难以有效抑制。本研究旨在提出一种基于矢量叠加的全光学采样保持方法，以增强PADC系统对时钟偏斜的抗扰能力。本文分析了PADC中多种系统参数（包括输入频率、带宽及时钟偏斜等）对采样保持效果的影响，并建立了系统性能响应的数学模型。本研究提出的方法通过引入不同波长的子光学脉冲，实现输入信号的同步采样，并通过精确时间延迟与相干耦合，将多路脉冲携带的采样信息进行叠加，这使得离散采样点被转换为连续采样时隙，从而显著减小多通道间的时钟偏斜和延时偏差所带来的影响。该采样保持机制具有系统复杂度低、功耗低及宽频带覆盖等优势。在实验中，该方法无需复杂校准即可抑制多通道时间错配。实测结果显示，本工作在±0.1采样周期范围内实现了时钟偏斜免疫，并保持了高于60 dB的无杂散动态范围（SFDR）。
摘要：
Precise clock synchronization dramatically increases the difficulty of designing large-scale and high-resolution channel-interleaved photonic analog-to-digital converters (PADCs). This paper presents a novel all-optical sample-and-hold method based on vector superposition. Closed-form equations are analyzed and derived to characterize the impact of various system parameters, including input frequency, bandwidth, and clock skew. To enable the optical sampling front end function as an optical sample-and-hold (S&H) circuit, sub-optical pulses with additional wavelengths are incorporated for the simultaneous acquisition of input signals. By precisely delaying and coherently coupling identical sampled information carried by these sub-optical pulses, discrete sampling points are effectively converted into continuous intervals, thereby significantly mitigating temporal errors caused by inter-channel clock skew and timing mismatches. The proposed method features the advantages of low complexity, low power consumption, and the ability to function over a wide frequency range. In the experiment, the proposed signal-holding mechanism inherently suppresses multi-channel temporal mismatches without sophisticated calibrations. The measurements of the configured channel-interleaved PADC demonstrate clock skew immunity within a ± 0.1 sampling period range while maintaining a spurious-free dynamic range (SFDR) above 60 dB.