Abstract: The fusion splicer includes a first holding unit, a second holding unit, a screen, a first measurement device, a first driving unit, a second driving unit, and a third driving unit. The screen has a light guide portion through which only test light emitted from one of the plurality of cores of the first optical fiber can pass. The screen is disposed between the end face of the first optical fiber and the end face of the second optical fiber. The first measurement device measures the intensity of leakage light leaking from the second optical fiber. The third driving unit adjusts the position of the screen such that the light guide portion is aligned with one of the plurality of cores of the first optical fiber in the axial direction of the first optical fiber.

Abstract: A method for fusion splicing of a holey optical fiber with a cladding having a large number of air holes along the axis thereof to another optical fiber includes the use of arc discharge heating. First, the method uses arc discharge heating such that the temperature of a position rearward of an end surface of the holey optical fiber is higher than the temperature of the end surface, thereby making a tip portion of the holey optical fiber transparent. Next, the cores are aligned with one another. Then the method includes performing fusion splicing by second arc discharge heating. The first arc discharge heating is performed between discharge electrodes positioned rearward of the end surface of the holey optical fiber. The arc heating time of the first arc discharge heating is preferably 200 to 400 milliseconds.

Abstract: A method for fusion splicing of a holey optical fiber with a cladding having a large number of air holes along the axis thereof to another optical fiber includes the use of arc discharge heating. First, the method uses arc discharge heating such that the temperature of a position rearward of an end surface of the holey optical fiber is higher than the temperature of the end surface, thereby making a tip portion of the holey optical fiber transparent. Next, the cores are aligned with one another. Then the method includes performing fusion splicing by second arc discharge heating. The first arc discharge heating is performed between discharge electrodes positioned rearward of the end surface of the holey optical fiber. The arc heating time of the first arc discharge heating is preferably 200 to 400 milliseconds.

Abstract: A fiber bundle is provided which has various advantages: limitation in terms of heat-resistant temperature is less; its manufacturing is easy and low-cost; and it will not degrade the optical fiber properties. The fiber bundle 10, which transmits through element fibers 11 light incident from light sources and emits the light from the respective output surface 11A altogether, has a structure in which at least one end parts of the element fibers 11 are collectively inserted into a metal sleeve 12 and the one end parts are solidified to be united with the sleeve 12, and in which a metal 13, that is a filler, is filled among the element fibers 11, in the sleeve 12, over a region of a given length L in the longitudinal direction of the sleeve 12 from the emitting-end face 12A of the sleeve 12.

Abstract: An optical fiber bundle that has better ultraviolet resistance characteristics at a wavelength range of 150 to 250 nm and that can be readily and cheaply manufactured with no risk of, for example, explosion during manufacturing and its manufacturing method are provided. In the optical fiber bundle, optical fibers including a core mainly containing silica glass and a cladding containing silica glass and fluorine are bundled and accommodated in a container. This container has optically transparent ends, accommodates hydrogen or deuterium as well as the optical fibers, and is sealed. The capacity of the container is 10 times or less as large as the volume of glass of the optical fibers.

Abstract: An optical fiber bundle that has better ultraviolet resistance characteristics at a wavelength range of 150 to 250 nm and that can be readily and cheaply manufactured with no risk of, for example, explosion during manufacturing and its manufacturing method are provided. In the optical fiber bundle, optical fibers including a core mainly containing silica glass and a cladding containing silica glass and fluorine are bundled and accommodated in a container. This container has optically transparent ends, accommodates hydrogen or deuterium as well as the optical fibers, and is sealed. The capacity of the container is 10 times or less as large as the volume of glass of the optical fibers.

Abstract: The invention relates to an amplification optical fiber that is suitable for amplification of signals in the L-band, that has the effect of suppressing normal four-wave mixing (FWM) occurring between signals, and that has the structure for effectively suppressing occurrence of non-degenerative FWM as well, and a fiber optic amplifier including the same. A fiber optic amplifier according to the present invention incorporates an amplification optical fiber having a core region doped with a rare earth element, a zero-dispersion wavelength of not more than a wavelength of pumping light, and an effective cutoff wavelength of 1.1 ?m or more but not more than the wavelength of the pumping light. Not only the normal FWM but also the non-degenerative FWM is effectively suppressed by application of the amplification optical fiber.

Abstract: The invention relates to an amplification optical fiber that is suitable for amplification of signals in the L-band, that has the effect of suppressing normal four-wave mixing (FWM) occurring between signals, and that has the structure for effectively suppressing occurrence of non-degenerative FWM as well, and a fiber optic amplifier including the same. A fiber optic amplifier according to the present invention incorporates an amplification optical fiber having a core region doped with a rare earth element, a zero-dispersion wavelength of not more than a wavelength of pumping light, and an effective cutoff wavelength of 1.1 &mgr;m or more but not more than the wavelength of the pumping light. Not only the normal FWM but also the non-degenerative FWM is effectively suppressed by application of the amplification optical fiber.