Disclosed is a mode field modifier for use with an optical fiber having a core and a cladding of outside diameter d. The modifier comprises a modifier core having a refractive index n1. Surrounding the modifier core is first cladding layer having a refractive index n2 that is less n1. On the surface of the first cladding layer is a second cladding layer having a refractive index n3 which is less than n2. The modifier is tapered intermediate its ends whereby it has a large diameter end and a small diameter end. The diameters of at least the core and first cladding layer at the large diameter end are greater than the corresponding diameters at the small end. The diameter D1 of the first cladding layer at the large diameter end is greater than d. An axially disposed hole in the large diameter end receives a fiber which is held in such alignment with the mode field modifier that it is in light coupling relationship with the modifier core. The mode field of a signal coupled from the fiber to the mode field modifier expands as it propagates though the tapered portion of the modifier to the small diameter end. An in-line coupler between two optical fibers is effected by connecting together in axial alignment two such mode field modifiers with their small diameter ends adjacent one another.

Connector employing mode field modification

PROBLEM TO BE SOLVED: To provide an optical fiber laser device that can improve power density of light produced by an optical fiber laser within a fiber by using a simplified structure. SOLUTION: An optical fiber 101 with a large core diameter and an optical fiber 103 with a small core diameter are arranged in an optical fiber laser resonator 108. The fiber 101 is added with rare earth, and excited light is emitted thereto for stimulated emission. The fibers 101 and 102 are optically connected with each other by means of a tapered optical guide 102. Thus, in such a state that the excited light can be easily emitted to the fiber 101, laser light is enclosed within a fiber 103, thereby improving the power density of light.

Optical fiber laser device

PURPOSE:To reduce the leak of light in input and output terminals by coating fiber side faces near input and output terminal faces of an optical fiber with a metallic layer whose reflection factor of light is >=95% with respect to the wavelength of a related light. CONSTITUTION:An optical fiber 1 is the fiber for energy transmission, and an optical fiber end face 4 is the input or output terminal. A cylindrical metallic layer 2 having a uniform thickness and a conical metallic layer 3 whose thick ness is reduced to zero gradually are provided in order from the optical fiber end face 4. If a layer surface 8 on the side opposite to the metallic layer is rugged, the light leaked to this rugged part is absorbed strongly by the rugged ness to reduce considerably a maximum transmission power. Since it is difficult to form the layer surface 8 perpendicular to the outside peripheral surface of the optical fiber to a flat surface, the thickness of the layer is reduced gradu ally. Gold, silver, aluminum, or the like which has >=95% reflection factor for the wavelength of transmitted light is used as materials of the metallic layer. Thus, the light is less leaked in the intermediate part and the ligth is transmit ted stably.

Fiber for optical energy transmission

A connecting structure for connecting optical conductors through which light energy is transmitted. The connecting structure comprises a coupling ring of an inner diameter approximately equal to the outer diameter of the optical conductor rod, an edge surface of the optical conductor rod and that of another optical conductor rod to be connected with it in the coupling ring and being arranged so as to be opposed to each other or an edge surface of the optical conductor rod and that of a large number of the optical fibers being arranged so as to be opposed to each other, the edge surfaces being connected through the use of matching oil or optical paste.

A connecting structure for connecting optical conductor

PROBLEM TO BE SOLVED: To provide an optical connector which restrains a reduction in optical transmission efficiency due to expansion of a wavelength range of transmission light without causing increases in cost and the size of the device.SOLUTION: The present invention comprises an SI type light source side optical fiber 10 arranged at a light source side and an SI type light receiving side optical fiber 20 arranged at a light receiving side. In optically connecting the light source side optical fiber 10 and the light receiving side optical fiber 20 by arranging an edge face 11 of the light source side optical fiber 10 and an edge face 21 of the light receiving side optical fiber 20 opposite to each other, the light source side optical fiber 10 and the light receiving side optical fiber 20 are detachable and the light source side optical fiber 10 has a taper section 14 with a diameter of a core section 12 increasing towards the edge face 11 of the light source side optical fiber 10.

Optical connector and endoscope system

PURPOSE:To improve the optical coupling efficiency by making an optical fiber having a smaller core diameter so taper as to have a larger numerical aperture and by giving a special condition to the taper angle when the optical fiber is coupled to an optical fiber having a larger core diameter.

Tousen Takashi

Papers

Optical fiber device and production thereof