Abstract: [Object] To provide a vertical cavity surface emitting laser device having a concave mirror structure and excellent polarization controllability. [Solving Means] A vertical cavity surface emitting laser device according to the present technology includes: a first light-reflecting layer; a second light-reflecting layer; and a stacked body. The stacked body includes a first semiconductor layer, a second semiconductor layer, and an active layer, and is disposed between the first light-reflecting layer and the second light-reflecting layer. The stacked body has a current confinement structure for confining a current and forming a current injection region where a current concentrates. The first light-reflecting layer includes a concave mirror having a concave surface on a side of the stacked body and a convex surface on a side opposite to the stacked body.

Abstract: The present technology provides a surface emitting element capable of enabling highly accurate detection of an optical characteristic of an emitted light and/or enabling adjustment of the optical characteristic of the emitted light. The surface emitting element of the present technology provides a surface emitting element including a light emitting layer, a characteristic layer that is disposed on an optical path of light generated in the light emitting layer, exhibits an electrical characteristic due to light incidence, and/or has variability in an optical characteristic due to voltage application, and a plurality of electrodes provided on the characteristic layer.

Abstract: The present invention relates to a polyimide film prepared from a tetracarboxylic acid component and a diamine component, wherein the strength of orientation anisotropy in the film length of 2000 mm is 1.2 or less and/or the strength of orientation anisotropy in the film length of 1800 mm is 1.1 or less.

Abstract: 2,3,3?,4?-biphenyltetracarboxylic acid is heat-dehydrated in a molten state at a temperature not lower than 200° C. in a flow of an inert gas in a reactor 10 having at least one reaction vessel 11 by stirring the molten material to produce 2,3,3?,4?-biphenyltetracarboxylic dianhydride. Thus obtained 2,3,3?,4?-biphenyltetracarboxylic dianhydride in the molten state is subsequently cooled and solidified in an inert gas or dry air, or cooled and solidified in the ambient air at a temperature of 40° C. or lower or 100° C. or higher.

Abstract: 2,3,3?,4?-biphenyltetracarboxylic acid is heat-dehydrated in a molten state at a temperature not lower than 200° C. in a flow of an inert gas in a reactor 10 having at least one reaction vessel 11 by stirring the molten material to produce 2,3,3?,4?-biphenyltetracarboxylic dianhydride. Thus obtained 2,3,3?,4?-biphenyltetracarboxylic dianhydride in the molten state is subsequently cooled and solidified in an inert gas or dry air, or cooled and solidified in the ambient air at a temperature of 40° C. or lower or 100° C. or higher.

Abstract: A process for producing 2,3,3?,4?-biphenyltetracarboxylic dianhydride (a-BPDA), comprising dehydrating 2,3,3?,4?-biphenyltetracarboxylic acid in an inert gas atmosphere under heating at 180 to 195° C. is disclosed. This process produces high-purity a-BPDA which is suitable for production of a polyimide.

Abstract: A process for producing 2,3,3?,4?-biphenyltetracarboxylic dianhydride (a-BPDA), comprising dehydrating 2,3,3?,4?-biphenyltetracarboxylic acid in an inert gas atmosphere under heating at 180 to 195° C is disclosed. This process produces high-purity a-BPDA which is suitable for production of a polyimide.