Abstract: An optical communication system has a configuration in which an optical transmission line is laid between a repeater (transmitter) and another repeater (receiver). The optical transmission line is formed by fusion-splicing a first optical fiber on the upstream side and a second optical fiber on the downstream side. The first optical fiber has a transmission loss of 0.25 dB or less, and an effective area of 80 ?m2 or above (preferably 100 ?m2 or above), at a wavelength of 1550 nm, which is the wavelength of signal light. The second optical fiber is connected to the downstream end of the first optical fiber and has positive dispersion regions and negative dispersion regions which are alternately arranged along the longitudinal direction and whose chromatic dispersions at a wavelength of 1550 nm are positive and negative, respectively.

Abstract: An optical fiber composite that can easily have a desired mean transmission property as a whole even after a length of optical fiber is cut off from one end or both ends, a cable comprising the composites, and methods for producing the composite and cable. An optical fiber composite 10 is produced by splicing a first optical fiber 11, a second optical fiber 12, and a third optical fiber 13 in this order. The first optical fiber 11 and the third optical fiber 13 each have a first chromatic dispersion, D1, at the wavelength of a signal-carrying lightwave. The second optical fiber 12 has a second chromatic dispersion, D2, at the wavelength of the signal-carrying lightwave. The third optical fiber has a length, L3, shorter than the length, L1, of the first optical fiber. It is desirable that the ratio L3/L1 be at most 0.1.

Abstract: A small optical device which has low power consumption and which is excellent for integration, and which has a variable optical attenuation function which features proper polarization dependence over the entire wide variable optical attenuation range is provided. In the optical device, an optical circuit including a core and a cladding that covers the core is formed on a substrate. An optical element is movably disposed inside a groove provided in the substrate so as to traverse the core, and includes a plurality of optical attenuation elements having different light attenuation amounts. By moving the optical element by an actuation function portion provided on the optical circuit, the attenuation amount of signal light that propagates through the optical circuit is changed.

Abstract: An image forming apparatus for forming an image with a developing agent, includes: a collecting-developing-agent occurring part in which the collecting developing agent to be collected in the developing agent occurs; a collection container for accommodating the collecting developing agent; a transporting part provided so as to connect the collection container and the collecting-developing-agent occurring part and for collecting and transporting the collecting developing agent occurring in the collecting-developing-agent occurring part; and a replacement part removably mounted in an apparatus body, wherein the collection container is mounted to be integrated with the replacement part.

Abstract: An optical signal, which is to become the subject of dispersion compensation, is split by optical combining/splitting unit 2, and each frequency component of the optical signal that is split is reflected by the corresponding reflective mirror 30 included in reflective mirror group 3 to apply a predetermined phase shift to the respective frequency components Each reflected frequency component is then combined using optical combining/splitting unit 2, to give dispersion compensated optical signal Furthermore, in regards to reflective mirror group 3, which is used to apply phase shift to each frequency component of an optical signal, each of the respective plurality of reflective mirrors 30 is made a movable mirror having a movable reflection position that reflects the frequency components. Through this, dispersion that develops in an optical signal may be compensated with favorable controllability and high accuracy.

Abstract: In an optical fiber including a core region and cladding regions of not less than three layers which surrounds the core region in order, each of said cladding regions has a mean refractive index different from those of the adjacents regions,at least one of the cladding regions has a lower mean refractive index than both adjacent regions, and at least one cladding region is provided with a plurality of sub medium regions each having a refractive index lower than a main medium constituting this cladding region.

Abstract: An optical fiber composite that can easily have a desired mean transmission property as a whole even after a length of optical fiber is cut off from one end or both ends, a cable comprising the composites, and methods for producing the composite and cable. An optical fiber composite 10 is produced by splicing a first optical fiber 11, a second optical fiber 12, and a third optical fiber 13 in this order. The first optical fiber 11 and the third optical fiber 13 each have a first chromatic dispersion, D1, at the wavelength of a signal-carrying lightwave. The second optical fiber 12 has a second chromatic dispersion, D2, at the wavelength of the signal-carrying lightwave. The third optical fiber has a length, L3, shorter than the length, L1, of the first optical fiber. It is desirable that the ratio L3/L1 be at most 0.1.

Abstract: The present invention discloses an optical transmission line constructing method comprising the steps of connecting a plurality of optical fibers differing from each other in terms of a transmission characteristic; making inspection light incident on an entrance end of the connected plurality of optical fibers; detecting, on the entrance end side, respective return light components of the inspection light occurring at individual positions of the plurality of optical fibers in its longitudinal direction; evaluating a characteristic information distribution of return light in the longitudinal direction of the plurality of optical fibers; and constructing an optical transmission line according to a result of the evaluation.

Abstract: The present invention relates to an optical transmission system having a structure to enable signal transmission while maintaining superior transmission characteristics over a broader wavelength band. Signal light outputted from a signal light source has a positive chirp, and propagates through a transmission line fiber to an optical receiver, after being Raman-amplified by a lumped Raman amplifier. The lumped Raman amplifier includes, as a Raman amplification fiber, a high-nonlinearity fiber having a negative chromatic dispersion at a wavelength of the signal light and intentionally generating a self-phase modulation therein. The positive chirp of the signal light propagating through the high-nonlinearity fiber is effectively compensated by both of the negative chromatic dispersion and the self-phase modulation generated in the high-nonlinearity fiber.

Abstract: An optical transmission path in a Raman gain module (1) for transmitting signal light input from an input terminal (1a) and Raman-amplifying the signal light by pumping light supplied from pumping light source units (21, 22) is formed by connecting in series two Raman amplification optical fibers (11, 12) having different wavelength dispersion values. According to this arrangement, wavelength dispersion in the amplifier module (1) can be controlled using, e.g., the combination of the wavelength dispersion values of the Raman amplification optical fibers (11, 12). Hence, accumulation of dispersion into signal light and signal light transmission in an almost zero dispersion state are prevented, and degradation in signal light transmission quality due to the nonlinear optical effect is suppressed.

Abstract: The present invention relates to an optical communication system having a flat gain spectrum and an excellent pumping efficiency in a signal wavelength band, and comprising a structure which is realizable/operable at a low cost. This optical communication system comprises an optical transmission line including a plurality of Raman amplification optical fibers, and pumping light suppliers for supplying pumping light to the Raman amplification optical fibers. In particular, two Raman amplification optical fibers selected from the plurality of Raman amplification optical fibers included in the optical transmission line differ from each other in at least one of the wavelength at which the gain of Raman amplification becomes the highest, and the number of channels at which the gain of Raman amplification is maximum.

Abstract: The present invention provides a Raman amplification pumping module and others with a structure for effectively suppressing degradation of quality of signal light even with a breakdown in either one of a plurality of light sources. The Raman amplification pumping module is provided with light sources for emitting respective lightwaves with center wavelengths different from each other, and each of the center wavelengths of the lightwaves from these light sources is adjusted so that a difference between two center wavelengths selected therefrom is less than 6 nm.

Abstract: The present invention relates to an optical transmission line enabling Raman amplification of an optical signal when pumping light is supplied thereto, a method of making this optical transmission line, and an optical transmission system using this optical transmission line. This optical transmission line is an optical transmission line enabling Raman amplification of an optical signal when pumping light is supplied thereto, wherein a region yielding the maximum value of Raman gain coefficient is separated from an end portion where the pumping light is supplied by a predetermined distance along a direction in which the pumping light advances.

Abstract: An optical module has a planar waveguide which is provided with an optical circuit for an optical switch formed by 2×2 cross optical waveguides A1 to D1 and an optical circuit for an optical variable attenuator formed by 2×2 cross optical waveguides A2 to D2. Joined onto the planar waveguide is an actuator structure and the actuator structure is constituted by an actuator section for an optical switch and an actuator section for an optical variable attenuator. The optical circuit of the planar waveguide and the actuator section constitute an optical switch, whereas the optical circuit of the planar waveguide 2 and the actuator section constitute an optical variable attenuator.

Abstract: The present invention relates to a Raman amplification method realizing Raman amplification of WDM signal light in a wider amplification wavelength band with a simpler configuration, and the like. A Raman amplifier realizing the Raman amplification method comprises a Raman amplification optical fiber, and a pumping light source for supplying pumping light having a wavelength &lgr;p to the amplification optical fiber. In the Raman amplifier, a part of the signal light is Raman-amplified with the pumping light having the wavelength &lgr;p, whereas a part of the Raman-amplified light is utilized as pumping light. This Raman-amplifies signal light including a channel wavelength with a wavelength of (&lgr;p+&Dgr;&lgr;+20 nm) or longer, where &Dgr;&lgr; is the Raman shift amount of wavelength caused by the pumping light at the wavelength &lgr;p.

Abstract: The present invention relates to an optical transmission line enabling Raman amplification of an optical signal when pumping light is supplied thereto, a method of making this optical transmission line, and an optical transmission system using this optical transmission line. This optical transmission line is an optical transmission line enabling Raman amplification of an optical signal when pumping light is supplied thereto, wherein a region yielding the maximum value of Raman gain coefficient is separated from an end portion where the pumping light is supplied by a predetermined distance along a direction in which the pumping light advances.

Abstract: An optical fiber has a section of the first kind having a chromatic dispersion not less than a given positive value x and a negative chromatic dispersion slope at a given wavelength and a section of the second kind has a chromatic dispersion not more than −x and a positive chromatic dispersion slope at the same wavelength. Another optical fiber has a chromatic dispersion higher than a positive value x and a negative chromatic dispersion slope at a given wavelength band.

Abstract: An optical switch that can restrain the occurrence of cross talk is provided. A first waveguide path 11 and a second waveguide path 12 are provided on a waveguide substrate PCL so as to intersect each other at a given angle. A trench T is formed in a straight line in the surface of the waveguide substrate PCL so as to cross the central axes of the first waveguide path and the second waveguide path. The trench T is as deep as to expose the whole end face of the first waveguide path and the second waveguide path. The first waveguide path 11 and the second waveguide path 12 are arranged such that their central axes are arranged asymmetrically with respect to the straight line.

Abstract: A Raman amplifier having a great Raman amplification gain is disclosed. An optical transmission system 1 is provided with an optical fiber 31 for Raman amplification and an optical multiplexer 41 between a transmitter 10 and a receiver 20 in the order of enumeration, and further provided with a pump light source 51 for Raman amplification that is connected with the optical multiplexer 41. The wavelength of signal light to be transmitted from the transmitter 10 to the receiver 20 is at 1.65 &mgr;m band, and the wavelength of the pump light that is output from the light source 51 is C-band or L-band. Since the pump light for Raman amplification propagates at a low loss through the optical fiber for Raman amplification, a great Raman amplification gain can be attained by the Raman amplifier.

Abstract: An optical variable attenuator has a planar waveguide, which is provided with optical waveguides forming an input optical line A and an output optical line B. A cantilever is disposed at the upper face of the planar waveguide, whereas a movable mirror for reflecting light passing through the input optical line A toward the output optical line B is secured to the leading end part of the cantilever. An electrode is disposed at the upper face of the planar waveguide. The cantilever and the electrode are connected to each other by way of a voltage source. The voltage source applies a voltage between the cantilever and the electrode, so as to generate an electrostatic force therebetween, which flexes the leading end side of the cantilever toward the electrode. As a consequence, the movable mirror moves toward the electrode.