Bilayer photonic crystal photoswitch thin-film device and preparation method thereof
A bilayer photonic crystal photoswitch thin-film device having the optical characteristics of both 2D and 3D photonic crystals, and a preparation method thereof are provided. When the bilayer photonic crystal photoswitch thin-film device is rotated periodically, different colors can be observed at a fixed rotation angle, that is, the device has the attribute of changing colors by means of rotation, and can thus realize the opening and closing of an optical path. The bilayer photonic crystal photoswitch thin-film new device has broad application prospects in the fields of photoswitches, optical waveguides, optical prisms, warming signs, anti-counterfeiting and information coding, etc.
1. A bilayer photonic crystal photoswitch thin-film device, comprising two opal photonic crystal templates with different thicknesses and a flexible polymer thin-film material, wherein the templates are assembled by nanospheres and combined by perpendicular dislocation into a “sandwich” structure, and the flexible polymer thin-film material is prepared by copolymerization of a precursor solution under an action of ultraviolet light, wherein the precursor solution is prepared by acrylic acid and esters thereof, mercaptoacrylates and photoinitiator; wherein, by rotating the bilayer photonic crystal photoswitch thin-film along a horizontal direction of the bilayer photonic crystal photoswitch thin-film, opening and closing of two periodically controllable optical paths of 30° and 60° are realized.
2. The bilayer photonic crystal photoswitch thin-film device according to claim 1 , wherein a boundary value of the two opal photonic crystal templates with different thicknesses ranges from 1 to 6 μm.
3. The bilayer photonic crystal photoswitch thin-film device according to claim 1 , wherein the nanospheres are silicon dioxide, titanium dioxide, polystyrene coated with silicon dioxide or titanium dioxide, polymethylmethacrylate coated with silicon dioxide or titanium dioxide, poly (styrene-methyl methacrylate-acrylic acid) polymer colloidal nanospheres coated with silicon dioxide or titanium dioxide, titanium dioxide coated with silicon dioxide, silicon dioxide coated with titanium dioxide, chromic oxide or zinc oxide; wherein each of the two opal photonic crystal templates is obtained by pulling and assembling the nanospheres.
4. The bilayer photonic crystal photoswitch thin-film device according to claim 1 , wherein a diameter of each of the nanospheres ranges from 250 to 550 nm.
5. The bilayer photonic crystal photoswtich thin-film device according to claim 1 , wherein the acrylic acid and esters thereof comprise triacrylates, diacrylatesoracrylic acids, wherein a volume ratio of the triacrylates, diacrylates and acrylic acids ranges from (0.1 to 6):(0.1 to 6):(0.1 to 6).
6. The bilayer photonic crystal photoswtich thin-film device according to claim 1 , wherein the mercaptoacrylates is selected from one of tetra (3-mercaptopropionic acid) esters, tris (3-mercaptopropionic acid) esters and di (3-mercaptopropionic acid) esters; wherein a volume ratio of the mercaptoacrylates to the triacry late ranges from 0.1-1:1.
7. The bilayer photonic crystal photoswitch thin-film device according to claim 1 , wherein the photoinitiator is selected from one or two of 2-oxhydryl-2-methyl-1-phenyl-1-acetone, 1-oxhydrylcyclohexyl phenyl acetone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-acetone, 2-benzyl-2-dimethylamino-1-(4-morpholinephenyl) butanone, phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, benzoin dimethyl ether, and benzoin diethyl ether, wherein a volume ratio of the photoinitiator to the triacrylate class ranges from 0.01-0.05:1.
8. A method for preparing the bilayer photonic crystal photoswitch thin-film device according to claim 1 , comprising following steps:
S1. preparing, at room temperature, a plurality of nanosphere opal photonic crystal templates on a glass substrate by pulling and self-assembly;
S2. combining, in dislocation manner by 90°, two of the plurality of nanosphere opal photonic crystal templates with different thicknesses, and separating the two templates by a polyimide tape to form a “sandwich” structure;
S3. mixing the triacrylates, diacrylates, acrylic acids, mercaptoacrylates and photoinitiator, and perfusing, after ultrasonic dispersion uniformly, the mixture into the templates of the “sandwich” structure obtained in step S2 for ultraviolet light curing; and
S4. stripping the outside glass substrates to obtain a bilayer photonic crystal containing nanospheres.
9. The method for preparing the bilayer photonic crystal photoswitch thin-film device according to claim 8 , wherein the nanospheres in the bilayer photonic crystal containing nanospheres obtained in the Step S4 are retained or removed.
10. The method for preparing the bilayer photonic crystal photoswitch thin-film device according to claim 8 , wherein in step S1, each of the plurality of nanosphere opal photonic crystal templates is mechanically engraved to obtain a patterned template.