Abstract: An optical fiber made of quartz or glass and having a core and a cladding includes a microporous silica solution applied to an outer peripheral surface thereof, which is synthesized from a mixture of silicon alcoxide, active alcohol for facilitating hydrolytic action, alcohol, and water, by means of the sol-gel process, followed by baking to form a thin film of microporous silica made chiefly of silicon. Microporous of the thin film of microporous silica have function of cushioning to cushion and restrain that micro cracks much existing in the cladding undergo growth when the optical fiber is bent so that the optical fiber is likely to be broken. And the thin film of microporous silica which made chiefly of silicon has high heat-resistant properties similarly to the optical fiber itself. Accordingly, a heat-resistant optical fiber very excellent in heat-resistant properties is provided.

Abstract: While clamped by a clamping jig 100, polarization-maintaining fiber cables 11 and 12 are automatically oriented with an orientation adjusting unit 200 and then heated by a heater 105 for curing thermoset resins.

Abstract: To the outer peripheral surface of an optical fiber made of quartz or glass and having a core and a cladding is applied a microporous silica solution, which is synthesized from a mixture of silicon alcoxide, active alcohol for facilitating hydrolytic action, alcohol, and water, by means of the sol-gel process, followed by baking to form a thin film of microporous silica made chiefly of silicon. Microporous of the thin film of microporous silica have function of cushioning to cushion and restrain that micro cracks much existing in the cladding undergo growth when the optical fiber is bent so that the optical fiber is likely to be broken. And the thin film of microporous silica which made chiefly of silicon has high heat-resistant properties similarly to the optical fiber itself. Accordingly, a heat-resistant optical fiber very excellent in heat-resistant properties is provided.

Abstract: To the outer peripheral surface of an optical fiber made of quartz or glass and having a core and a cladding is applied a microporous silica solution, which is synthesized from a mixture of silicon alcoxide, active alcohol for facilitating hydrolytic action, alcohol, and water, by means of the sol-gel process, followed by baking to form a thin film of microporous silica made chiefly of silicon. Microporous of the thin film of microporous silica have function of cushioning to cushion and restrain that micro cracks much existing in the cladding undergo growth when the optical fiber is bent so that the optical fiber is likely to be broken. And the thin film of microporous silica which made chiefly of silicon has high heat-resistant properties similarly to the optical fiber itself. Accordingly, a heat-resistant optical fiber very excellent in heat-resistant properties is provided.

Abstract: While clamped by a clamping jig 100, polarization-maintaining fiber cables 11 and 12 are automatically oriented with an orientation adjusting unit 200 and then heated by a heater 105 for curing thermoset resins.

Abstract: While clamped by a clamping jig 100, polarization-maintaining fiber cables 11 and 12 are automatically oriented with an orientation adjusting unit 200 and then heated by a heater 105 for curing thermoset resins.

Abstract: While clamped by a clamping jig 100, polarization-maintaining fiber cables 11 and 12 are automatically oriented with an orientation adjusting unit 200 and then heated by a heater 105 for curing thermoset resins.

Abstract: A twin-core ferrule structure is provided which is miniaturized in size, facilitated for accurate positioning the optical axes of two optical fibers, and improved both in degree of freedom of determining a shape and in high-volume productivity.

Abstract: To avoid change in the property of an optical fiber, an optical fiber cord 100 has a structure fabricated by exposing a portion of the optical fiber 1 located at one end of an optical fiber core 15 which comprises a cushion layer 2 provided over the outer side of the optical fiber 1 and a cladding 3 provided over the outer side of the cushion layer 2; protecting one end of the exposed portion of the optical fiber 1 adjacent to the end of the cushion layer 3 with a roll of low hardness resin 4; and bonding the exposed portion of the optical fiber 1 to the capillary 32 of a ferrule 30 by an adhesive 20 so that the one end of the optical fiber core 15 is fixed integral with the ferrule 30. The stress of thermal shrinkage of the adhesive 20 is attenuated by the action of the low hardness resin 4 thus hardly acting on the optical fiber 1. Accordingly, a change in the property of the optical fiber 1 such as mode shift can be avoided.

Abstract: One or more parts of an optical fiber is(are) exposed to a high temperature of gas flame for about 30 minutes so as to form one or more radially expanded core part(s) where a diameter of a core of the optical fiber is increased greater than its original size at a center and moderately decreased back to its original size as departing from the center. A part of the transmitting light leaks to the clad at the radially expanded core part. Leaked light hardly travels through the clad from the radially expanded core part to the output end of the optical fiber. This provides a function of an optical attenuator. Also, the attenuation is precisely adjusted to a desired level by controlling a size of the radially expanded core part. Furthermore, as an incident angle of the transmitting light from the core to the clad at the radially expanded core part becomes greater than conventional one, reflecting back the transmitting light to input side is prevented and the reflectance is minimized.