Abstract: An optical fiber whose chromatic dispersions have an opposite sign relative to those of the 1380 nm zero-dispersion fiber at all of the wavelengths in the range of 1450 nm to 1620 nm is provided. This optical fiber has negative chromatic dispersions at all of the wavelengths in this range and the values of which are −7 ps·nm−1·km−1 or more but −1 ps·nm−1·km−1 or less at a wavelength of 1450 nm, −12 ps·nm−1·km−1 or more but −5 ps·nm−1·km−1 or less at a wavelength of 1550 nm and −17 ps·nm−1·km−1 or more but −6 ps·nm−1·km−1 or less at a wavelength of 1620 nm. This optical fiber can compensate the dispersions of 1380 nm zero-dispersion fiber over the entire wavelength in this range.

Abstract: The present invention relates to a dispersion-shifted optical fiber suitable for an optical transmission line having an optical fiber amplifier with a wider amplification band. In particular, the dispersion-shifted optical fiber according to the present invention has a zero-dispersion wavelength of 1610 nm or more but 1750 nm or less, and a cutoff wavelength of 1.1 &mgr;m or more at a length of 2 m in order to suppress the bending loss to a practically permissible range, and has, with respect to light having a wavelength of 1550 nm, an effective area of 45 &mgr;m2 or more and a dispersion slope of 0.15 ps/nm2/km or less in order to suppress the occurrence of nonlinear phenomena.

Abstract: A fiber optic cable is provided which can perform a long-distance signal light transmission at high bit rates even if any temporal temperature change or regional temperature difference occurs. Also provided is an optical transmission system in which signal light can be transmitted at high bit rates over a long distance, from a transmitting station to a receiving station, even if a temporal temperature change or a regional temperature difference occurs to the fiber optic cables installed between the transmitting station and the receiving station. The fiber optic cable comprises a plurality of optical fibers bundled therein having an absolute value of 0.001 ps·nm−1·km31 1·K−1 or less, more preferably 0.0005 ps·nm−1·km−1·K−1 or less, of chromatic dispersion variation quantity per unit temperature at a wavelength of 1550 nm. The fiber optic cable preferably has a loose tubal structure or loose slotted structure.

Abstract: The present invention relates to an optical transmission line and the like having a chromatic dispersion with a small absolute value as a whole within a signal wavelength band including S, C, and L bands.

Abstract: The invention is directed to a dispersion-compensating optical fiber which can compensate for the chromatic dispersion and dispersion slope of a non-zero dispersion-shifted optical fiber by a short length. The dispersion-shifted optical fiber constitutes an optical transmission line together with a dispersion-compensating optical fiber fusion-spliced thereto. The dispersion-compensating optical fiber has, at a wavelength of 1550 nm, a chromatic dispersion DDCF of −40 ps/nm/km or less and a ratio (DDCF/SDCF) of dispersion slope SDCF to the chromatic dispersion DDCF of 0.005/nm or more.

Abstract: A first electrode layer having a first electrodeless portion is formed on the upper surface of a dielectric plate, a second electrode layer having a second electrodeless portion opposing the first electrodeless portion is forced on the lower surface of a second dielectric plate, and electric lines are formed by an intermediate electrode layer formed between the first and second electrode layers.

Abstract: The present invention relates to an optical fiber transmission line having a structure offering superior connection loss characteristics at the fusion-spliced position between optical fibers. This optical fiber transmission line has at least first and second optical fibers that are fusion-spliced. Each of these first and second optical fibers has a core region doped with 10 mol % or more of Ge and has a mode field diameter with a minimum value of 7 &mgr;m or less at the wavelength of 1550 nm. The difference between the minimum mode diameter of the first optical fiber and that of the second optical fiber is 1 &mgr;m or less.

Abstract: A radio-frequency amplifier comprises slot lines formed in a top electrode which are bent to define matching segments that are perpendicular to transmitting segments. The matching segments have a length corresponding to one-quarter of the wavelength of a signal to be amplified and are at least partially perpendicular to the transmitting segments. A DC-cut circuit comprising slot lines is connected to the matching segments, an FET is connected to the transmitting segments and the matching segments, and respective matching circuits serve as an input unit and an output unit of the FET. Source terminals of the FET are connected to parts of a top electrode that do not lie between the segments. A drain terminal and a gate terminal are connected, to be electrically separated from each other, to parts of the top electrode, which are electrically separated from the source terminals by the DC-cut circuit, the transmitting segments, and the matching segments.

Abstract: The present invention relates to a single-mode optical fiber having a configuration which enables lowering of dispersion slope while securing a sufficient MFD. This single-mode optical fiber has a refractive index profile in which an indent with a sufficient width is provided at the center of its core region. In particular, this indent satisfies the following relationship: a·(&Dgr;n2−&Dgr;n1)/(b·&Dgr;n2)≧0.04 when the first core portion in the single-mode optical fiber has a mean relative refractive index difference of &Dgr;n1 with respect to the cladding portion and an outer diameter of a while the second core portion has a mean relative refractive index difference of &Dgr;n1 with respect to the cladding portion and an outer diameter of b.

Abstract: A method of splicing optical fibers is provided to reduce the splicing loss of the first and second optical fibers having different MFDs from each other. In a pre-fusion heating step, the MFD at the adjacent end face of the optical fiber having larger MFD is enlarged by heating a portion including the adjacent end face thereof so as to diffuse a dopant. After the pre-fusion heating step, fusion-splicing of the first and the second optical fibers is performed. Thereafter, during the post-fusion heating step, the dopant is diffused by heating a portion including the fusion-spliced part between the first and the second optical fibers.

Abstract: The present invention relates to an optical fiber having a large positive dispersion in a wavelength band of 1.55 &mgr;m in order to compensate for a negative dispersion inherent in an NZ-DSF in the wavelength band of 1.55 &mgr;m. This optical fiber comprises a depressed cladding structure constituted by a core region; an inner cladding, disposed at the outer periphery of the core region, having a lower refractive index; and an outer cladding having a higher refractive index. In this optical fiber, the relative refractive index difference of the core region with respect to the outer cladding is at least 0.30% but not greater than 0.50%, and the relative refractive index difference of the inner cladding with respect to the outer cladding is at least −0.50% but not greater than −0.02%. Also, the optical fiber has a dispersion greater than 18 ps/nm/km at a wavelength of 1.55 &mgr;m, and an effective cross-sectional area Aeff of at least 70 &mgr;m2 at the wavelength of 1.55 &mgr;m.

Abstract: The present invention relates to an optical fiber which enables favorable optical communications in 1.3-&mgr;m and 1.55-&mgr;m wavelength bands, and an optical transmission system including the same. The optical fiber according to the present invention has only one zero-dispersion wavelength within a wavelength range of 1.20 &mgr;m to 1.60 &mgr;m, the zero-dispersion wavelength existing within a wavelength range of 1.37 &mgr;m to 1.50 &mgr;m, and has a positive dispersion slope at the zero-dispersion wavelength, thereby enabling favorable optical communications utilizing each signal light in the 1.3-&mgr;m and 1.55-&mgr;m wavelength bands sandwiching the zero-dispersion wavelength.

Abstract: The present invention concerns a negative-dispersion optical fiber for compensating in a shorter length for chromatic dispersion of a positive-dispersion optical fiber in a signal wavelength band, and an optical transmission line incorporating it. The negative-dispersion optical fiber has the following properties at the wavelength of 1550 nm; chromatic dispersion D of not more than −150 ps/nm/km; a dispersion slope satisfying such a condition that a ratio thereof (S/D) to the chromatic dispersion D is not less than 2.0×10−3/nm nor more than 4.7×1031 3/nm; and an effective area of not less than 12 &mgr;m2 but less than 25 &mgr;m2. For satisfying these properties, the negative-dispersion optical fiber has, in the order stated from the center toward the outer periphery, a core region of a maximum refractive index n1, a first cladding of a refractive index n2 (<n1), a second cladding of a refractive index n3 (>n2), and a third cladding of a refractive index n4 (<n3).

Abstract: Electrodes are formed on both top and bottom surfaces of a dielectric plate and grounded coplanar lines, as transmission lines, are formed on the top surface of the dielectric plate. A plurality of micro-strip lines, each composed of high-impedance lines and low-impedance lines alternately connected in series, is arranged at a pitch shorter than the wavelength of a wave traveling along the grounded coplanar lines. A spurious mode propagation blocking circuit thus constructed prevents a spurious mode wave, such as a parallel-plate mode, from traveling.

Abstract: There is provided an optical fiber transmission-line with which the four-wave mixing generation can be suppressed effectively and also transmission loss is small. An optical fiber transmission-line 10 is dispersion-managed by a single silica optical fiber thereof being provided alternately in its longitudinal direction with parts 10a where the chromatic dispersion at the wavelength 1550 nm is positive and parts 10b where it is negative. In any one repeater span of the transmission-line there are at least four sign change positions P at which the sign of the chromatic dispersion changes in the longitudinal direction; the absolute value of the average changing rate of chromatic dispersion in each sign change locality A, each sign change locality A being a range including a sign change position P over which the absolute value of the chromatic dispersion is less than 2 ps/nm/km, is not less than 0.

Abstract: The present invention concerns a negative-dispersion optical fiber for compensating in a shorter length for chromatic dispersion of a positive-dispersion optical fiber in a signal wavelength band, and an optical transmission line incorporating it. The negative-dispersion optical fiber has the following properties at the wavelength of 1550 nm; chromatic dispersion D of not more than −150 ps/nm/km; a dispersion slope satisfying such a condition that a ratio thereof (S/D) to the chromatic dispersion D is not less than 2.0×10−3/nm nor more than 4.7×10−3/nm; and an effective area of not less than 12 &mgr;m2 but less than 25 &mgr;m2.

Abstract: A high-frequency module which includes a dielectric resonator defined by a dielectric sheet; a pair of electrodes formed on each of the main surfaces of the dielectric sheet and having aligned openings which form a dielectric resonator; a substrate stacked on the sheet; and lines disposed on the substrate for being coupled to the dielectric resonator. At least one of the lines is curved and is disposed just inside the opening and runs substantially along the edges of the openings.

Abstract: The present invention relates to a dispersion-shifted optical fiber which comprises a structure for effectively eliminating the causes of deterioration in characteristics at the making stage thereof and is suitable for wavelength division multiplexing transmission. In the dispersion-shifted optical fiber according to the present invention, impurities to be added and the contents thereof are adjusted so as to reduce viscosity difference at each interface between individual glass regions. As a consequence of this structure, occurrence of structural irregularity and glass defect are effectively restrained in the vicinity of the interfaces between the regions.

Abstract: An optical fiber comprising a core region 100 doped with Cl which raises the refractive index; and a cladding region 200, provided at the outer periphery of the core region 100, having a cladding layer 201 doped with F which lowers the refractive index is formed. The cladding region 201 to become the outermost cladding layer is configured such that the doping amount of F successively decreases within an outer peripheral part 205 including the outer periphery thereof to a predetermined doping amount which is the minimum doping amount of F within the cladding layer 201. Therefore, the stress within the optical fiber is dispersed into the outer peripheral part 205 having an enhanced viscosity, whereby the stress concentration into the core is suppressed. Since the favorable tension range at the time of drawing the optical fiber becomes wider at this time, tension control is facilitated.

Abstract: An information delivery system includes an information delivery apparatus installed at a sales company and receiver apparatuses installed at sales shops. A control unit generates program information data from stored program contents including catalog information, and generates delivery schedule information data based on stored delivery information. The program information data and the delivery schedule information data are transmitted by a broadband transmitter unit to the receiver apparatuses. The delivery schedule information is also transmitted to the receiver apparatuses, as required, via a narrowband communication path. In each receiver apparatus, a broadband receiver unit and a narrowband receiver unit receives the program information data and the delivery schedule information data, and the program contents are retrieved as desired and stored. A display unit displays the retrieved catalog information under the control of an information retrieval control unit.