4/27/2024 0 Comments 3d coat alpha circle fade![]() To this end, liquid crystal blue phases are promising candidates as they self-organize into 3D periodic structures. The use of materials with intrinsic chirality is an alternative approach to realize CP-selective optical devices. However, while nanofabrication can confer nontrivial functionality onto thin substrates, their fabrication is costly, making scaling up a technological challenge. The light wavefront can thus be modified by controlling the distribution of the optic axis orientation, and the phase gradient is reversed for orthogonal CP components, enabling multiple functions to be integrated into a single device. In a Pancharatnam-Berry phase device, the CP of light incident on the device acquires an optical phase that is proportional to twice the orientation of the optic axis, as well as reversing its handedness. The Pancharatnam-Berry phase in subwavelength anisotropic nanostructures has led to a plethora of CP-selective diffractive optical elements (DOEs) 6, 7. Gyroid photonic crystals with I4 132 symmetry have been demonstrated to split a light beam into orthogonal CP components 5. Various devices have been proposed with strong CP selectivity, based on artificially engineered photonic crystals 2 and metasurfaces 3, 4. In particular, circular-polarization (CP) selectivity has drawn considerable interest in the past decade because of its relevance in nature and its potential for novel applications 1. The ability to affect only a single polarization of an orthogonal polarization pair is a basic yet important functionality that is relevant to a wide range of applications, from displays to sensing. The search for nanostructures with advanced light-matter interactions has both fundamental and practical significance. Such devices are difficult to fabricate using conventional optical materials, thereby demonstrating the potential of self-organizing soft matter for photonics. 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. 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 direction aligned along the surface anchoring. 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. 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. Controlling the crystallographic orientation of 3D photonic crystals is important as it determines the behavior of light propagating through the device.
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