Abstract: A first directional coupler branching input light into a cross-port path having a branching ratio ? and a bar-port path having a branching ratio 1-?. A first arm propagating light from the cross-port path of the first directional coupler; a second arm propagating light from the bar-port path of the first directional coupler. A second directional coupler outputting output light acquired by combining the light being input from the first arm and the light being input from the second arm at the cross-port branching ratio ? and the bar-port branching ratio 1-?. A phase modulation unit providing a phase difference between the light propagating through the first arm and the light propagating through the second arm. ? and 1-?, and ? and 1-? are determined such that an a parameter being a chirp parameter is a negative value.

Abstract: The ball of the present invention is characterized by including at least one skin layer having water absorbability. The at least one skin layer may be formed of a water absorbent material, or may be formed so as to include a surface portion and a water absorbent outer skin adhered to at least a part of the surface portion. According to the ball of the present invention, a ball for competitions that can easily maintain water absorbency is provided while remaining durable even when used for a long time and not requiring man-hours during the manufacturing process.

Abstract: The ball of the present invention is characterized by including at least one skin layer having water absorbability. The at least one skin layer may be formed of a water absorbent material, or may be formed so as to include a surface portion and a water absorbent outer skin adhered to at least a part of the surface portion. According to the ball of the present invention, a ball for competitions that can easily maintain water absorbency is provided while remaining durable even when used for a long time and not requiring man-hours during the manufacturing process.