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【研究进展】大范围连续可调的分数阶光学时域微分器

发布时间:2018-03-22 11:39

光学运算器件如光学时域微分器、光学时域积分器、光学希尔伯特变换器等在全光信号处理领域扮演着重要角色,它们直接在光域进行数据处理和数学运算,从而有着广泛应用。光学时域微分器是一种非常重要的光信号处理器件,它在全光信号处理与光计算、脉冲编码、光学测量、脉冲整形和光学传感等领域中的众多优点和广泛应用。近些年来,基于光纤光栅、马赫-曾德尔干涉仪和硅基微环谐振器等方案的光学时域微分器不断地被提出。但是,他们或多或少存在着微分阶数固定,对偏振敏感,制备复杂和调节范围窄等缺陷。


1 MZI耦合微环结构的光学时域微分器示意图与显微图

2 输入高斯脉冲波形与实验得到的微分结果图

针对以上问题华中科技大学武汉光电国家实验室的张新亮教授、董建绩教授和学生刘冕、赵雨赫等人,利用微环耦合型干涉仪结构实现光学时域微分运算(如图1所示)。实验结果表明,通过调节热电极所施加的电压值,器件的微分阶数从0.25-1.75连续可调且平均误差小于6%(如图2所示),是目前已知的调谐范围最大的单微环结构光学微分器。通过调节微环谐振器上方的热电极,器件的工作波长也可以有效的调节。这一研究发现可直接应用于未来的硅基光子集成技术

   20171225日,该成果以题目“Widely tunable fractional-order photonic differentiator using a Mach–Zenhder interferometer coupled microring resonator”在线发表在美国光学学会(OSA)旗下杂志Optics Express上(Volume 25,Issue 26, Pages 33305-33314)。该工作受到了国家优秀青年科学基金和国家自然科学基金的支持。

Widely tunable fractional-order photonic differentiator

The photonic temporal differentiator has received great attention due to its many advantages and wide applications in optical processing and computing, pulse coding, pulse shaping, and optical sensing, which is one of the basic and critical devices for all-optical signal processing. In recent years, lots of schemes have been proposed to perform photonic temporal differentiator, including the use of the long-period fiber grating, the phase-shifted fiber Bragg grating (FBG), the semiconductor optical amplifier (SOA), the Mach–Zehnder interferometer (MZI), and the silicon microring resonator (MRR). However, a widely tunable fractional-order differentiator with robust and convenient operation has not been reported yet.

Based on these problems above, the Professor Jianji Dong’s team proposed and experimentally demonstrated a novel photonic temporal differentiator using a Mach–Zenhder interferometer coupled microring resonator, as the Fig1. The proposed differentiator presents a tunable differentiation order range of 0.25 to 1.75, and the average errors are less than 6%, which is the largest tuning range of a tunable photonic differentiator using a single microring resonator to the best of our knowledge, as the Fig2. The proposed scheme which might be valuable towards the large scale silicon-based photonic integration.

On December 25, 2017, this work is published on Optics Express (Volume 25, Issue 26, Pages 33305-33314) with the title of Widely tunable fractional-order photonic differentiator using a Mach–Zenhder interferometer coupled microring resonator. The work is supported by the National Natural Science Foundation of China (NSFC) (61475052, 61622502).