Abstract: A laser module for transmitting/receiving digital signals using a laser diode as an optical source is disclosed. The input end of the laser module is provided with a low pass filter, such that the low pass filter makes a 3 dB bandwidth of frequency response transferred from the input pins to the laser diode to be equal or less than the on-state relaxation oscillation frequency of the laser diode, wherein the overshoot is minimized by adjusting a relative amount of the frequency component input to the laser diode.

Abstract: Disclosed is a distributed Bragg reflector laser, which includes: an active layer; a first guide layer provided with a plurality of first gratings on an upper surface thereof and formed on one side of the active layer; and, a second guide layer provided with a plurality of second gratings on an upper surface thereof, wherein the second guide layer is formed on the other side of the active layer opposite to the first guide layer.

Abstract: Disclosed is an optical-fiber preform having barrier layers to hydroxyl radicals, the optical-fiber preform comprising: a quartz tube in the form of a cylinder shape serving as a substrate for forming the optical-fiber preform; a first barrier layer for preventing hydroxyl radicals from permeating the optical-fiber preform and deposited onto the inner surface of the quartz tube; a second barrier layer having a permeation coefficient higher than the first barrier layer and deposited onto the first barrier layer; a third barrier layer having a permeation coefficient lower than the second barrier layer and deposited onto the second barrier layer; and, a core layer being located at the center of the optical-fiber preform.

Abstract: An optical add/drop multiplexer includes a multiplexing/demultiplexing unit having an input multiplexing port, an output multiplexing port and a plurality of demultiplexing ports each connected to a respective optical circulator. Each optical circulator includes a first port for internally inputting an added channel, a second port for outputting the added channel to a corresponding demultiplexing port and receiving a channel outputted by the corresponding demultiplexing port, and a third port for outputting the channel received from the second port.

Abstract: A planar light wave circuit is disclosed, which comprises: a first waveguide for receiving optical signals from an outside; a second waveguide having a first end surface and a second end surface, so that lights outputted from the first waveguide are partially reflected by the first end surface and are partially incidented into the first end surface and then outputted through the second end surface; a third waveguide for receiving the light reflected by the first end surface; and a common region bordering each end surface of the first to the third waveguides and having an index of refraction different from an index of refraction of the second waveguide.

Abstract: Disclosed is a wide-band dispersion controlled optical fiber. The optical fiber enables the use of optical signals in various wavelength regions in a wavelength division multiplexing mode communication network by controlling the position of the zero dispersion wavelength, and enables long distance transmission by controlling dispersion slope and bending loss. Furthermore, there is an advantage in that the optical fiber enables not only short distance transmission but also middle/long distance transmission using a single type of optical fiber because the optical fiber is controlled to have negative dispersion values in the O-band wavelength region and positive dispersion values with small deviations in the C-band and L-band wavelength regions.

Abstract: A method for processing a great amount of intra-calls in the remote control system of a full electronic exchange system, whose time switch block is provided with a voice memory device and a control memory device to switch the PCM data to the intra-direction, and with a call pass controller to transfer to the host system or loop to the intra-direction the PCM data, comprises the steps of writing call direction data for designating the intra-call direction into the data region of the control memory device to switch the PCM data sequentially stored in the voice memory device to the intra-direction, and looping the entire channels to the intra-direction to switch the PCM data from the time switch block to the intra-direction if the call direction data designates the intra-call direction according to the treatment of the great amount of the intra-calls.

Abstract: Disclosed is a node structure of an upgradeable wavelength division multiplexing system that can minimize the expense in implementing, maintaining, and upgrading the system. The node structure includes an interleaver for interleaving a plurality of optical signals received therein into a predetermined number of channels; at least one demultiplexer coupled to one of the output channels for demultiplexing the optical signals received thereto into a prescribed number of channels; at least one multiplexer for multiplexing the respective demultiplexed optical signals from the demultiplexer; and, a deinterleaver for deinterleaving the optical signals outputted from the multiplexer to be forwarded to the next node.

Abstract: A method for controlling the hand-off of an MS (Mobile Station) for the home zone service in a mobile telecommunications system including a plurality of BTSs (Base Transceiver Stations), a BSC for controlling the BTSs, and an MSC (Mobile Switching Center) for connecting the BSC with a different BTS or network, comprising the steps of causing the MS to connect through the BTS with the BSC (Base Station Controller) by an outgoing or incoming call, causing the BSC to store the home zone list and the subscriber service class of the MS received from the MSC, and causing the BSC to perform the hand-off requested by the MS according to the home zone list and the subscriber service class. Thus, when the MS registered only in the fixed network, so as to be provided with communication services only in the home zone, travels through the other regions than the home zone, the BTS drops the presently connected call with an alert message.

Abstract: Disclosed is an optical fiber comprising a center core which forms a passageway for transmitting optical signals and has a refractive index N1, and a cladding which encloses the center core and has a refractive index N0. The optical fiber further comprises an upper core, which has a distribution of refractive indices increased starting from a refractive index N2 (>N0) at its outer circumference to the refractive index N1 at its internal circumference, and a minutely depressed refractive index region, which is interposed between said upper core and cladding and has a refractive index N3. The refractive index N3 is lower than the refractive index N0.

Abstract: Disclosed is an air-blown fiber-optic cable including: a central tensile member which is located axially through the center of the optic cable and provides a tension-resistant force; a plurality of loose tubes wound around the tensile member, each tube housing a plurality of optic fibers therein; aramid yarns for binding the loose tubes; and an outer sheath disposed on the outermost part of the optic cable to protect the interior thereof from the exterior environment.

Abstract: Disclosed is a fiber optic cable, comprising a central strength member, disposed at the center of the cable, for providing tensile strength; a plurality of inner tight buffered cores disposed in a linear form around the central strength member; a plurality of outer tight buffered cores, twisted in a spiral or S-Z form, for enclosing the inner tight buffered cores; and a jacket, disposed on an outermost circumference of the cable, for protecting an interior of the cable from external environments.

Abstract: There is provided an optical signal monitoring method and apparatus for measuring the characteristics of an input WDM optical signal. In the optical signal monitoring method, the WDM optical signal is combined with reference lights at both sides of the WDM optical signal on the wavelength spectrum. The combined signal is input to a filter having a variable transmission wavelength according to an applied driving voltage. A driving voltage-light intensity graph of a combined optical signal detected from the filter is derived in its overall wavelength band. A linear approximated wavelength is obtained with respect to a driving voltage and a non-linear compensated wavelength is calculated in a predetermined non-linear compensation formula with the driving voltage and the operation temperature of the filter.

Abstract: Disclosed is an amplifying optical fiber for amplifying optical signal transmitted therethrough by stimulated emission, the amplifying optical fiber comprising: an inner core disposed at a center of said optical fiber and containing MX, GaS3/2 and RE; an outer core surrounding said inner core and containing SiO2; and a cladding surrounding said outer core and containing SiO2, wherein said M contained in MX is one component selected from the group consisting of Na, K, Rb and Cs; said X contained in MX is one component selected from the group consisting of F, Cl, Br, and I; and said RE is one component selected from the group consisting of Ce, Pr, Pm, Nd, Sm, Eu, Gd, Tb, Ho, Dy, Er, Tm and Yb.

Abstract: Disclosed is a raw material-providing device for a chemical-vapor deposition process and includes: a bubbler for vaporizing liquid raw material and providing the vaporized raw material to a deposition unit; and a raw material tank for providing liquid raw material to the bubbler, wherein the raw material tank preserves liquid raw material to be provided to the bubbler in advance and preheats the liquid raw material, and the raw material inside the raw material tank is provided to the bubbler through a plurality of hollow micro tubes, and wherein as the raw material inside the bubbler is gradually consumed, the internal pressure of the raw material tank is adjusted to change the amount of the raw material to be provided to the bubbler, thereby adjusting the amount of the raw material inside the bubbler and the vapor pressure inside the bubbler.

Abstract: A plastic optical fiber and a method for producing the same is disclosed. The plastic optical fiber is formed as a fiber of core-cladding structure. A protective layer or shield layer may be provided on the outer surface of the optical fiber of core-cladding structure for improving thermal resistance of the optical fiber and protecting the optical fiber from air and moisture. The plastic optical fiber uses fluorinated plastic, which contains a rare earth component as a core material, and a cladding material, which does not comprise a rare earth component but essentially consists of a polymer chain, which essentially consists of bonded —[CF2]n— monomers and has a refractive index lower than that of the core material. The optical fiber is produced by a melting-drawing technique.

Abstract: This invention relates to an alignment apparatus for aligning a planar optical wave-guide element and an optical fiber block wherein alignment can be completed with more precision and less expense than conventional methods. The alignment apparatus comprising a lower plate; a sliding table mounted on the lower plate capable of horizontal displacement on the lower plate; an upper plate mounted to the sliding table; and, a jig disposed on the upper plate and fixed to rotational means and capable of rotation about the upper plate for holding the optical fiber block.

Abstract: The fishing rod of this invention includes a hollow cylindrical butt pipe, and a plurality of hollow cylindrical sections sequentially jointed together to form a telescopically retractable structure jointed to the butt pipe such that the sections are sequentially retracted into the butt pipe. A tip rod is mounted to the end of the outermost one of the sections remote from the butt pipe. A butt grip is fitted over the butt pipe, and consists of a hollow cylindrical tube opened at both ends thereof. A plurality of radial support ribs are formed on the inner surface of the tube while being directed in radial directions and spaced apart from each other at regular intervals. When the butt grip is fitted over the butt pipe, the external surface of the butt pipe is brought into close contact with the inside edges of the radial support ribs.

Abstract: An optical fiber amplifier is disclosed for amplifying an input optical signal in the long wavelength band. The amplifier include first and second pumping light sources, a photo detector for detecting the intensity of the input optical signal, an erbium-doped optical fiber, and a controller. The optical fiber is brought to a first-pumped state by the first pumping light output from the first pumping light source. This generates an amplified spontaneous emission in the short wavelength band. The optical fiber is brought to a second-pumped state by the amplified spontaneous emission and outputs an induced emission light in the long wavelength band. The second pumping light source outputs a second pumping light in the same wavelength band as the amplified spontaneous emission, while controlling the intensity of the second pumping light by an output control signal, thereby controlling the intensity of the second-pumped state of the optical fiber.

Abstract: The present invention discloses a long-band Erbium doped-fiber amplifier including: a first Erbium doped fiber with a predetermined length, coupled to a first pumping light source through a first wavelength-selective coupler, for amplifying a C-band optical signal by supplied pumping light; a second Erbium doped fiber with a predetermined length for amplifying an L-band optical signal by a second pumping light source; a feedback loop for recycling a specific C-band wavelength generated in the amplification of the first Erbium doped fiber as the second pumping light source of the L-band optical signal; a tap coupler formed between the first and second Erbium doped fibers, for dividing the optical power amplified in the first Erbium doped fiber, for supplying a predetermined ratio of optical power to the second Erbium doped fiber, and for re-inputting the residual optical power to the feedback loop; and, a second wavelength-selective coupler for coupling the signal light transmitted from the tap coupler to the