An optical circuit device comprises a substrate (10) of a III-V group compound semiconductor, and a magnetic semiconductor layer (14) having a chalcopyrite type crystal structure. A magnetic semiconductor having the chalcopyrite type crystal structure is a material which can provide the Faraday effect, and, therefore, can be used to form a Faraday rotation element (22). Furthermore, a magnetic semiconductor having the chalcopyrite type crystal structure that is lattice-matched with the substrate (10), has fewer crystal defects, which can reduce light loss from the Faraday rotation element (22). A magnetic semiconductor of the chalcopyrite type crystal structure can provide a large Verdet's constant, which makes it possible to reduce a length of the Faraday rotation element (22) and, therefore, to micronize such an optical circuit device.

A semiconductor optical device having an optical waveguide (2a) which represents nonlinear refractive index change due to control light absorption. The waveguide (2a) has a bandgap wavelength that increases from its entrance (9) to its exit (10). In the case of the waveguide divided into first (4) to n-th regions, the bandgap wavelengths λ₁, λ₂, ..., λ_n-1, λ_n of the regions satisfy the relationship λ₁ < λ₂ < ...< λ_n-1 < λ_n. In the case of the waveguide not divided into regions, the bandgap wavelength λ of the waveguide monotonously increases from the entrance to the exit. This device can operate by the control light having a lower energy than the conventional one.

A liquid crystal display device includes a first substrate; a thin film transistor on the first substrate; a first passivation layer on the thin film transistor; a first electrode on the first passivation layer; a second passivation layer on the first electrode; a second electrode of an oxide semiconductor on the second passivation layer; and an alignment layer on the second electrode, wherein the second electrode includes first portions and second portions, and the second portions have a conductor property.

A display device according to an exemplary embodiment includes: a substrate (110) including a display area (DA) and a peripheral area (PA); a thin film transistor (Q) positioned in the display area (DA) of the substrate (110); a first electrode (191) connected to the thin film transistor (Q); a roof layer (360) positioned on the first electrode (191) and spaced apart from the first electrode (191) by a microcavity (305) that is interposed between the roof layer (360) and the first electrode (191); a liquid crystal layer (310) positioned inside the microcavity (305); an encapsulation layer (390) positioned on the roof layer (360); a pad portion (GP, DP) positioned in the peripheral area (PA) of the substrate (110); and a pillar (500) positioned in the peripheral area (PA) of the substrate (110).

The present invention provides a polarizer and a polarization modulation system. The polarizer includes at least one MMI multi-mode waveguide, where one side of each MMI multi-mode waveguide is connected to an input waveguide, and the other side is connected to an output waveguide; an end portion of the side, on which the output waveguide is located, of the MMI multi-mode waveguide is provided with an adjustable portion, and the adjustable portion is connected to the output waveguide; and the polarizer further includes a controller connected to the adjustable portion, where the controller is configured to perform control to change a material property of the adjustable portion, so that the output waveguide outputs optical signals in different polarization states. The present invention implements adjustable polarization, and the structure is simple.

Provided is a liquid crystal display device including first and second opposing substrates, a liquid crystal layer containing a liquid crystal composition between the first and second substrates, thin-film transistors disposed on the first substrate, and pixel electrodes that are driven by the transistors and that are made of a transparent conductive material. Each thin-film transistor includes a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer. The liquid crystal composition contains at least one compound selected from the group consisting of compounds represented by general formulas (LC3) to (LC5) and at least one compound selected from the group consisting of compounds represented by general formulas (II-a) to (II-f).