US 11,796,840 B2
Electrically controlled polarization rotator
Tsung-Hsien Lin, Kaohsiung (TW); Heng-Yi Tseng, Kaohsiung (TW); Cheng-Chang Li, Kaohsiung (TW); Duan-Yi Guo, Kaohsiung (TW); Li-Min Chang, Kaohsiung (TW); and Kuan-Wu Lin, Kaohsiung (TW)
Assigned to NATIONAL SUN YAT-SEN UNIVERSITY, Kaohsiung (TW)
Filed by NATIONAL SUN YAT-SEN UNIVERSITY, Kaohsiung (TW)
Filed on Sep. 27, 2021, as Appl. No. 17/485,549.
Claims priority of application No. 110127723 (TW), filed on Jul. 28, 2021.
Prior Publication US 2023/0031864 A1, Feb. 2, 2023
Int. Cl. G02F 1/01 (2006.01); G02F 1/1337 (2006.01)
CPC G02F 1/0136 (2013.01) [G02F 1/133738 (2021.01); G02F 1/133742 (2021.01); G02F 2202/06 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An electrically controlled polarization rotator, comprising:
two substrates having a homogeneous alignment and a homeotropic alignment respectively, with a distance between the two substrates being a liquid crystal thickness, wherein a switching electric field which is adjustable is provided between the two substrates, wherein a polarized light is incident on the substrate having the homogeneous alignment, and wherein a polarization direction of the polarized light is orthogonal or parallel to an alignment direction of the substrate having the homogeneous alignment; and
a liquid crystal layer located between the two substrates, wherein a birefringence of the liquid crystal layer multiplied by the liquid crystal thickness and further divided by a wavelength of the polarized light is greater than 10, and wherein the polarization direction of the polarized light is rotated corresponding to an intensity of the switching electric field in the liquid crystal layer;
wherein an angle between two alignment directions of the two substrates is a rotation angle;
wherein by specific relationships on the rotation angle and between the liquid crystal thickness and a pitch of the liquid crystal layer, the electrically controlled polarization rotator comprises a first configuration or a second configuration:
in the first configuration, the rotation angle is greater than 0 degrees and less than or equal to 90 degrees, wherein a ratio of the liquid crystal thickness to a pitch of the liquid crystal layer is less than or equal to ¼, and wherein the polarization direction of the polarized light is rotated between 0 degrees to the rotation angle;
in the second configuration, the rotation angle is greater than 90 degrees and less than or equal to 180 degrees, wherein a ratio of the liquid crystal thickness to a pitch of the liquid crystal layer is greater than ¼ and less than or equal to ¾, and wherein the polarization direction of the polarized light is rotated from half of the rotation angle to the rotation angle or is rotated from half of the rotation angle to 0 degrees.