Controlling the crystallographic orientation of 3D photonic crystals is important as it determines the behavior of light propagating through the device. Blue phases self-assemble into unique soft 3D photonic crystals with chiral structures for circular-polarization selectivity, but it has remained a challenge to control its 3D orientation. Here, we show that the orientation of blue phases can be precisely controlled to follow a predefined pattern imprinted on a substrate by exploiting field-induced phase transitions. Obtaining the blue phase through the field-induced chiral nematic phase and tetragonal blue phase X results in a highly oriented blue phase I with the crystallographic [001] direction aligned along the surface anchoring. Our approach is applied to fabricating a Bragg-Berry hologram with omnidirectional circular-polarization selectivity, where the hologram is visible only for one circular-polarization under all incident angles. Such devices are difficult to fabricate using conventional optical materials, thereby demonstrating the potential of self-organizing soft matter for photonics.

控制3D光子晶体的晶体学取向非常重要，因为它可以确定通过设备传播的光的行为。蓝相可自组装成具有手性结构的独特软3D光子晶体，以实现圆偏振选择性，但控制其3D方向仍然是一个挑战。在这里，我们表明，通过利用场致相变，可以精确地控制蓝相的方向，以遵循印在基板上的预定图案。通过场诱导的手性向列相和四方蓝相X获得蓝相会导致高度取向的蓝相I，其晶体学[001]方向沿表面锚定对齐。我们的方法应用于制造具有全向圆偏振选择性的布拉格-贝瑞全息图，其中全息图仅在所有入射角下仅对一个圆偏振可见。使用常规的光学材料难以制造这样的装置，从而证明了自组织软物质对于光子学的潜力。