A photonic bandgap is a range of wavelengths wherein light is forbidden from entering a photonic crystal, similar to the electronic bandgap in semiconductors. Fabricating photonic crystals with a complete photonic bandgap in the visible spectrum presents at least two important challenges: achieving a material refractive index > ~2 and a three-dimensional patterning resolution better than ~280 nm (lattice constant of 400 nm). Here we show an approach to overcome such limitations using additive manufacturing, thus realizing high-quality, high-refractive index photonic crystals with size-tunable bandgaps across the visible spectrum. We develop a titanium ion-doped resin (Ti-Nano) for high-resolution printing by two-photon polymerization lithography. After printing, the structures are heat-treated in air to induce lattice shrinkage and produce titania nanostructures. We attain three-dimensional photonic crystals with patterning resolution as high as 180 nm and refractive index of 2.4–2.6. Optical characterization reveals ~100% reflectance within the photonic crystal bandgap in the visible range. Finally, we show capabilities in defining local defects and demonstrate proof-of-principle applications in spectrally selective perfect reflectors and chiral light discriminators.

光子带隙是禁止光进入光子晶体的波长范围，类似于半导体中的电子带隙。在可见光谱中制造具有完整光子带隙的光子晶体至少面临两个重要挑战：实现材料折射率 > ~2 和优于 ~280 nm（晶格常数为 400 nm）的三维图案化分辨率。在这里，我们展示了一种使用增材制造克服这些限制的方法，从而在可见光谱中实现高质量、高折射率的光子晶体，这些晶体具有尺寸可调的带隙。我们开发了一种钛离子掺杂树脂 （Ti-Nano），用于通过双光子聚合光刻进行高分辨率打印。打印后，结构在空气中进行热处理，以诱导晶格收缩并产生二氧化钛纳米结构。我们获得了图形化分辨率高达 180 nm、折射率为 2.4-2.6 的三维光子晶体。光学表征显示，在可见光范围内，光子晶体带隙内的反射率为 ~100%。最后，我们展示了定义局部缺陷的能力，并展示了光谱选择性完美反射器和手性光鉴别器中的原理验证应用。