A method for forming a side-pumped optical fiber combiner includes ablating a cladding of a signal fiber to form an angled notch in the cladding. The signal fiber includes a core and the cladding surrounding the core. The method further includes inserting a cladding-free end of a pump fiber into the angled notch. The pump fiber includes a core and a cladding, the cladding-free end including the core of the pump fiber and free from the cladding of the pump fiber. The method further includes fusing the cladding-free end to the signal fiber.

There is described a method of optically coupling a first optical fiber and a second optical fiber to one another. The method generally has a step of bringing a free end of the first optical fiber, the second optical fiber and liquid in close proximity to one another within a coupling region, the free end of the first optical fiber having a dimension below a critical dimension, the free end of the first optical fiber moving within said liquid to contact the second optical fiber along a given coupling length, said contact optically coupling the free end of the first optical fiber and the second optical fiber to one another.

An optical fiber side input and output device in which light can be input and output from the side of the tube core cable without adjusting a spacing even in a case where the thickness of the protective tube differs, and a method of designing the optical fiber side input and output device is provided. An optical fiber side input and output device has a structure in which an angle of a central angle of an apex portion of a first jig having a convex portion is appropriately set, and a loss insertion is kept equal to or less than a prescribed value by using a relationship between a spacing at the angle and an insertion loss when light is input and output from the side of the tube core cable.

An optical fiber includes a core configured to transmit laser light and a cladding that surrounds the core. In some implementations, an outer surface region of the cladding is tapered or comprises a plurality of notches. The outer surface region of the cladding is configured to cause an aiming beam that falls incident upon the outer surface region of the cladding at a first incidence angle to fall incident upon an outer surface region of the core at a second incidence angle to allow the aiming beam to couple into the core.

An object is to provide a highly versatile optical fiber local-light detection apparatus capable of supporting various types of coated optical fibers. An optical fiber local-light detection apparatus according to the present invention includes: a first jig 11 including a recess portion 22 curved along a longitudinal direction with respect to a coated optical fiber 100 and a light input/output unit 14 configured to emit light to the coated optical fiber 100 that is bent and to receive light leaking from the coated optical fiber 100; a second jig 12 including at least one protrusion portion 23 that is curved along the longitudinal direction with respect to the coated optical fiber 100, the second jig configured to clamp the coated optical fiber 100 with the recess portion 22 of the first jig 11, in accordance with a type of the coated optical fiber 100;
a pressing portion configured to apply pressing force in a direction in which the recess portion 22 of the first jig 11 and the at least one protrusion portion 23 of the second jig 12 mutually approach, to bend the coated optical fiber 100; and
a switching mechanism configured to switch the at least one protrusion portion 23 to a protrusion portion corresponding to the type of the coated optical fiber 100.

An object is to provide a highly versatile local-light detection apparatus for an optical fiber capable of supporting various types of coated optical fibers.

A local-light detection apparatus for an optical fiber according to the present invention includes a first jig including a recess curved in a longitudinal direction of a coated optical fiber and an optical input and output device configured to make light incident on the coated optical fiber in which a bend is formed and to receive light leaking from the coated optical fiber, a second jig including a protrusion curved in the longitudinal direction of the coated optical fiber, the protrusion being configured to sandwich the coated optical fiber between the recess of the first jig and the protrusion, a presser configured to apply a pressing force in a direction in which the recess of the first jig and the protrusion of the second jig approach each other and to form the bend in the coated optical fiber, and fiber guides disposed at both ends of the recess of the first jig in the longitudinal direction of the coated optical fiber, and to arrange the coated optical fiber on a predetermined path on the recess of the first jig regardless of a diameter of the coated optical fiber when the presser forms the bend in the coated optical fiber.

A connector includes a first light transmission part and a second light transmission part, and when the connector is connected to an optical component, observing, by using the first light transmission part and the second light transmission part on an equipment room side, a detection light to identify the connector, and identifying an output port through which a user-side optical network unit (ONU) is connected to an equipment-room-side splitter.

An aim is to provide an optical coupler that contributes increasing pump-efficiency in an optical amplifier, and the optical amplifier. The optical amplifier includes: a main optical fiber that includes a core transmitting signal light, an inner cladding portion formed around an outer periphery of the core and having a refractive index lower than a refractive index of the core, and an outer cladding portion formed around an outer periphery of the inner cladding portion and having a refractive index lower than the refractive index of the inner cladding portion, a part of the outer cladding portion of which in a longitudinal direction being removed; and at least one pump-light input-output optical fiber that is fusion-spliced to the inner cladding portion of the main optical fiber at the portion where the outer cladding portion is removed, an average refractive index of which in a contact region where the pump-light input-output optical fiber is in contact with the inner cladding portion being larger than the refractive index of the inner cladding portion. Pump-light propagating in the pump-light input-output optical fiber is coupled to the inner cladding portion from the contact region and propagates in the inner cladding portion, or the pump-light propagating in the inner cladding portion is coupled to the pump-light input-output optical fiber from the contact region and propagates in the pump-light input-output optical fiber.

An object is to provide an optical fiber side input and output device in which light can be input and output from the side of the tube core cable without adjusting a spacing S even in a case where the thickness of the protective tube differs, and a method of designing the optical fiber side input and output device. An optical fiber side input and output device according to the present invention has a structure in which an angle of a central angle of an apex portion of a first jig having a convex portion is appropriately set, and a loss insertion is kept equal to or less than a prescribed value by using a relationship between a spacing S at the angle and an insertion loss when light is input and output from the side of the tube core cable, even in a case which a thickness of a protective tube changes, and this eliminates the need of adjusting the spacing S.

An object of the present invention is to provide a probe optical fiber and a local-light coupling apparatus for an optical fiber that can input light with high efficiency without performing input efficiency measurement or probe alignment. The present invention is a probe optical fiber of which a tip is close to a bent part of a coated optical fiber disposed in a local-light coupling apparatus for an optical fiber, and which inputs and outputs light to and from the bent part of the coated optical fiber, wherein light emitted from the tip has a light intensity profile in which in the bent part of the coated optical fiber, relative to a light intensity in a center of an optical axis, a decrease in light intensity at a position separated by 20 μm from the optical axis is less than 17.6 dB.