Tunable face-centered-cubic photonic crystal formed in holographic polymer dispersed liquid crystals

Abstract

We report on the fabrication and electro-optic measurements of face-centered-cubic (fcc) lattices in holographic polymer dispersed liquid-crystal materials. Four linearly polarized coherent plane waves were interfered to generate a fcc optical lattice that was subsequently and indefinitely recorded as an arrayed pattern of nanometer-sized liquid-crystal droplets (approximately 50 nm) at lattice nodes within a polymer matrix. Observed transmission spectra and Kossel diffraction curves are consistent with fcc crystal structure. A completely reversible 2% wavelength shift of the (+/- 111) stop band was observed on application of an electric field.

Fabricating three‐dimensional polymeric photonic structures by multi‐beam interference lithography

“…12a-c) 86 , fcc (Fig. 12d-f) 87 , diamond-like fcc 88 , and orthorhombic P lattices (Fig. 12g-i) 89 have been demonstrated using three-beam, fourbeam, and six-beam interference, respectively (see Fig.…”

“…Source: from ref. 87 (g) Calculated isointensity surface of YZ-plane, (h) laser beam geometry, and (i) SEM image of (100) plane after removal of the liquid crystals in orthorhombic P lattice. Scale bar, 250 nm.…”

Woodpile-type photonic crystals with orthorhombic or tetragonal symmetry formed through phase mask techniques

“…However, it has been a great challenge to rapidly fabricate large-area and defect-free three-dimensional (3D) photonic crystals at low cost. Holographic lithography has recently been employed to fabricate 3D photonic crystals by exposing a photoresist or polymerizable resin to interference patterns of laser beams [2][3][4][5][6][7][8][9][10][11][12][13][14]. This multi-beam interference technique has produced defect free, nanometer-scale structures over large substrate areas [3].…”

“…A desired geometrical structure could be obtained by single or multiple exposures [6][7][8]10]. The holographic lithography has also been used to produce tunable photonic crystals in a liquid crystal and polymer system [13], and to demonstrate a chiral microstructure in SU-8 photoresist [14]. In the case of positive resist, the overexposed material is then dissolved away in the post-exposure processing.…”

Tunable all-optical switching in periodic structures with liquid-crystal defects

“…The main idea behind all those studies is the ability to continuously tune the bandgap spectrum of a periodic dielectric structure using the temperature dependent refractive index of a liquid crystal [4,5,6,7], or its property to change the refractive index under the action of an applied electric field [8,9,10].…”