Flexible diffraction gratings that can be dynamically tuned in terms of both diffraction efficiency and diffraction angles are very important components for various applications, and fundamentally can be tuned through varying the modulation depth, duty cycle and grating period. However, dynamic and continuous tuning of a grating in all three aspects is difficult and has never been demonstrated hitherto. We propose and successfully fabricate a laminar-flow-based microfluidic grating in which all the three parameters can be dynamically tuned by simply varying flow rates into several liquid inlets. A 32-period liquid grating is generated by using ethanol and benzyl alcohol as alternate liquid lamellae. The total diffraction efficiency is tuned between 0 and 99%, and the maximum diffraction efficiency of the first order is ∼27%. The duty cycle of the grating is dynamically tuned from 7.6% to 91.5%. The grating period is compressed from more than 22 μm to less than 4 μm, leading to tuning of the first order diffraction angle from 1.7° to 9.2°.

中文翻译：

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基于层流微流控光栅的周期、调制深度和占空比的广泛和连续动态调谐

可以在衍射效率和衍射角方面动态调谐的灵活衍射光栅是各种应用中非常重要的组成部分，从根本上可以通过改变调制深度、占空比和光栅周期来进行调谐。然而，光栅在所有三个方面的动态和连续调谐是困难的，迄今为止从未被证明过。我们提出并成功地制造了一种基于层流的微流体光栅，其中所有三个参数都可以通过简单地改变进入几个液体入口的流速来动态调整。通过使用乙醇和苯甲醇作为交替的液体薄片产生 32 周期的液体光栅。总衍射效率在 0 到 99% 之间调整，一阶最大衍射效率约为 27%。光栅的占空比从 7.6% 动态调谐到 91.5%。光栅周期从大于 22 μm 压缩到小于 4 μm，导致一阶衍射角从 1.7° 调整到 9.2°。