Abstract: An optical device may include a substrate, a metal layer on the substrate, at least one first nano-structure in the layer, and at least one second nano-structure in the layer. The at least one first nano-structure may include a light source. The at least one first and second nano-structures may be spaced apart. A method of controlling a propagation direction of light output from an optical device that includes a metal layer on a substrate may include disposing first and second nano-structures in the layer; disposing at least one light source in the first nano-structure; and controlling the propagation direction of the light output from the at least one light source by changing at least one of a shape of the first nano-structure, a shape of the second nano-structure, a size of the first nano-structure, a size of the second nano-structure, and an interval between the first and second nano-structures.

Abstract: Provided herein is a gas sensor apparatus including a first sensor unit, second sensor unit, and signal processing unit. The first sensor unit has a channel area doped to an n-type such that it may selectively react to a donor molecule in gas. The second sensor unit has a channel area doped to a p-type such that it may selectively react to an acceptor molecule in gas. The signal processing unit receives a sense signal of the donor molecule from the first sensor unit and a sense signal of the acceptor molecule from the second sensor unit, processes the received sense signals and generates result data of processing the received sense signals. Therefore, the gas sensor apparatus may selectively sense donor gas and acceptor gas.

Abstract: An optical device may include a substrate, a metal layer on the substrate, at least one first nano-structure in the layer, and at least one second nano-structure in the layer. The at least one first nano-structure may include a light source. The at least one first and second nano-structures may be spaced apart. A method of controlling a propagation direction of light output from an optical device that includes a metal layer on a substrate may include disposing first and second nano-structures in the layer; disposing at least one light source in the first nano-structure; and controlling the propagation direction of the light output from the at least one light source by changing at least one of a shape of the first nano-structure, a shape of the second nano-structure, a size of the first nano-structure, a size of the second nano-structure, and an interval between the first and second nano-structures.