Abstract: A fiber structure includes first and second optical fibers disposed such that end portions thereof butt, a sheet-shaped saturable absorber including a carbon nanotube and disposed between the end portion of the first optical fiber and the end portion of the second optical fiber, and a housing internally accommodating the end portion of the first optical fiber and the end portion of the second optical fiber. A space in the housing including the saturable absorber is airtight.

Abstract: A fiber structure includes first and second optical fibers disposed such that end portions thereof butt, a sheet-shaped saturable absorber including a carbon nanotube and disposed between the end portion of the first optical fiber and the end portion of the second optical fiber, and a housing internally accommodating the end portion of the first optical fiber and the end portion of the second optical fiber. A space in the housing including the saturable absorber is airtight.

Abstract: A fiber structure includes first and second optical fibers disposed such that tip portions thereof butt and a sheet-shaped saturable absorber sandwiched between the tip portion of the first optical fiber and the tip portion of the second optical fiber. Each of the tip portions of the first optical fiber and the second optical fiber has a core, a cladding provided around the core, and a ferrule provided around the cladding. The tip portion of the first optical fiber has a protruding shape protruding to a tip side. The saturable absorber has an adhering part at least adhering to the core of the first optical fiber and a non-adhering part present around the adhering part and not adhering to the tip portion of the first optical fiber.

Abstract: An electron tube includes a housing having an internal space airtightly sealed, and an electrode configured to generation or detection of energy by electron emission in the internal space. The housing has a main body part made of an insulating material and formed with a recess constituting the internal space, and a lid part fixed to the main body part so as to close an opening of the recess. The recess expands toward the opening side. The main body part is fixed with a penetrating member that is electrically connected to the electrode and passes through the main body part. The penetrating member has an internal space projecting part that projects from a bottom surface of the recess into the internal space.