We study the optical reflectivity of three-dimensional (3D) photonic band gap crystals with increasing thickness. The crystals consist of GaAs plates with nanorod arrays that are assembled by an advanced stacking method into high-quality 3D woodpile structures. We observe intense and broad reflectivity peak with stop bands that correspond to a broad gap in the photonic band structures. The maximum reflectivity quickly reaches high values even for a few crystal layers. Remarkably, the bandwidth of the stop bands hardly decreases with increasing crystal thickness, in good agreement with FDTD simulations. This behavior differs remarkably from the large changes observed earlier in weakly interacting 3D photonic crystals. The nearly constant bandwidth and high reflectivity are rationalized by multiple Bragg interference that occurs in strongly interacting photonic band gap crystals, whereby the incident light scatters from multiple reciprocal lattice vectors simultaneously, in particular from oblique ones that are parallel to a longer crystal dimension and thus experience hardly any finite size effects. Our new insights have favorable consequences for the application of 3D photonic band gap crystals, notably since even thin structures reveal the full band gap functionality, including devices that shield quantum bits from vacuum fluctuations.

中文翻译：

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有限厚度的3D GaAs光子带隙晶体的反射率

我们研究随着厚度增​​加的三维（3D）光子带隙晶体的光学反射率。晶体由具有纳米棒阵列的GaAs板组成，这些板通过先进的堆叠方法组装成高质量的3D木桩结构。我们观察到具有对应于光子带结构中的宽间隙的阻带的强烈且宽广的反射率峰。即使对于几个晶体层，最大反射率也很快达到高值。值得注意的是，阻带的带宽几乎不会随晶体厚度的增加而减小，这与FDTD模拟非常吻合。这种行为与早先在弱相互作用的3D光子晶体中观察到的大变化明显不同。通过在强烈相互作用的光子带隙晶体中发生的多个布拉格干涉，可以使接近恒定的带宽和高反射率合理化，从而使入射光同时从多个倒易晶格矢量（尤其是平行于较长晶体尺寸的倾斜晶格矢量）散射。几乎没有任何有限尺寸的效果。我们的新见解对3D光子带隙晶体的应用产生了有利的影响，特别是因为即使薄的结构也能显示出全带隙功能，包括使量子位免受真空波动影响的器件。尤其是平行于较长晶体尺寸的倾斜晶体，因此几乎不会受到任何有限尺寸的影响。我们的新见解对3D光子带隙晶体的应用产生了有利的影响，特别是因为即使薄的结构也能显示出全带隙功能，包括使量子位免受真空波动影响的器件。尤其是平行于较长晶体尺寸的倾斜晶体，因此几乎不会受到任何有限尺寸的影响。我们的新见解对3D光子带隙晶体的应用产生了有利的影响，特别是因为即使薄的结构也能显示出全带隙功能，包括使量子位免受真空波动影响的器件。