Abstract: Embodiments of the present invention relate to a fiber design that achieves high nonlinearity, an effective index providing phase matching for an illustrative wavelength conversion process, and a low sensitivity to perturbations in fiber scaling. In one embodiment, a fiber comprises an inner core having an inner core radius and an inner core index, an outer core having an outer core radius and an outer core index, the outer core index being lower than the inner core index, an inner cladding, having an inner cladding radius and an inner cladding index, the inner cladding index being less than the outer core index, and an effective index of the fiber, the effective index being greater than the inner cladding index and less than the outer core index, wherein the fiber has a low perturbation sensitivity factor of dispersion to scaling less than about 20 ps/nm/km along the length of the fiber.

Abstract: A system and an associated method of bidirectional optical transmission between a central terminal (101) and a plurality of client terminals (11, 12) via a passive optical network (PON) (3), wherein the conversion of an OTDM signal into a WDM signal (respectively the conversion of a WDM signal into an OTDM signal) is effected by an optical converter (20) (respectively 21) by a soliton trapping effect during a downlink (respectively uplink) transmission stage.

Abstract: Example embodiments may include a coaxial Free Space Optical (FSO) telescope providing a simplified and more precise structure. Example embodiment telescopes include a prism structure having at least two parallel surfaces associated with a filter and mirror. The filter may reflect or transmit optical signals based on their electromagnetic characteristics. Example embodiment systems include example embodiment coaxial FSO telescopes and transmitters and receivers for receiving and transmitting optical signals. A V-groove and/or lens array may be included in example embodiment FSO systems.

Abstract: The pulse light source according to the present invention comprises: a seed pulse generator 1 for outputting an input pulse 10 as a seed pulse; a pulse amplifier 2; and a dispersion compensator 3 for dispersion compensating a light pulse output from the pulse amplifier 2. Moreover, the pulse amplifier 2 comprises a normal dispersion medium (DCF 4) and an amplification medium (EDF 5) that are multistage-connected alternately, for changing the input pulse 10 to a light pulse having a linear chirp and outputting the light pulse. Furthermore, an absolute value of the dispersion of the DCF 4 becomes to be larger than the absolute value of the dispersion of the EDF 5.

Abstract: An image processing apparatus, which includes: an extraction section that extracts a drawing element to be printed in a black color; a contour portion determination section that determines a contour portion of the drawing element extracted by the extraction section; and a controller that controls a printing unit such that, for a portion determined as the contour portion by the contour portion determination section, the portion is overprinted on a printed background image, and for a portion not determined as the contour portion by the contour portion determination section, the portion is printed without printing the background image.

Abstract: Methods and apparatus are described for DWDM transport of CATV and digital signals over optical fiber in low-dispersion spectral regions. A method includes transporting a plurality of optical carriers of different wavelengths over an optical link using wavelength division multiplexing, the optical link including a plurality of optical segments. The plurality of optical channel center wavelengths defined by the plurality of optical carriers are clustered proximate an average value of a zero-dispersion wavelength of the optical link, or near either a) a low wavelength edge or b) a high wavelength edge of a range of zero-dispersion wavelengths of the optical link and a plurality of optical channel center frequencies defined by the plurality of optical channel center wavelengths are non-uniformly spaced apart.

Abstract: An apparatus includes an interleaver configuration for at least one of combining or separating odd and even channel groups to achieve channel density doubling; and an optical equalizer for suppressing inter symbol interference within the channels to provide intra-channel equalizing in the optical path, the equalizer being integrated into the interleaver. Preferably, optical equalizer and interleaver are integrated together as a single monolithic device, the optical equalizer includes a passband that has a dip in the channel center to achieve a raised-cosine filtering profile in the optical signal path to achieve inter-symbol interference ISI suppression, and the equalizer includes integration into the optical path of the interleaver to realize a monolithic device combining or separating odd and even channel groups to achieve channel density doubling.

Abstract: The invention relates to a device and a method for converting WDM signals into an OTDM signal. The device comprises shifting means (102, 103, 104) adapted to introduce a time shift between the pulses of the WDM signals carried by the optical carriers, modulation means (112, 113, 114) adapted to modify the optical power of the WDM signals, an optical temporal multiplexer/demultiplexer (120), a birefringent propagation medium (130) into which the WDM signals are injected in such a manner as to achieve a soliton trapping phenomenon, and absorption means (140) adapted to introduce optical losses into the components of the OTDM signal. This device performs WDM/OTDM conversion at very high bit rates. It also performs OTDM/WDM conversion. It is intended to be installed in long-haul telecommunication networks.

Abstract: Provided is an ultra-short pulse light source having an optical pulse generator 111 for emitting short pulse light, an optical amplifier 112 for amplifying the short pulse light output from the optical pulse generator 111 and an optical compressor 120 for compressing the short pulse light. The optical compressor 120 has multi-step configuration of steps polarization beam splitters 1211,2, optical fibers 1221,2,1231,2 for compressing the incident pulse light, polarization rotating element 1241,2, for rotating the polarization direction of the incident light by 90 degrees to return the light to the optical fibers 1231,2, polarization maintaining optical fibers 1251,2 provided to the output side of the polarization beam splitters 1211,2, and a polarization maintaining optical fiber 1251 at the front step is connected to a polarization maintaining optical fiber 1252 at the rear step.

Abstract: An OTDM transmitting method and transmitter realizing an OTDM distortion-free transmission substantially not relying upon dispersion. A time division multiplexed OTDM signal from an OTDM signal transmitter (1) enters an optical Fourier transform unit (2). Optical Fourier transform can be carried out most accurately so long as the optical pulse is a chirp-free Fourier transform limit pulse. The optical Fourier transform unit (2) converts the time waveform of the pulse into a signal on the frequency axis, and an optical inverse Fourier transform unit (2?) converts a spectral shape on the frequency axis into a time waveform (pulse). An optical fiber transmission line (3) is a transmission line having an arbitrary dispersion and a polarization mode dispersion. These dispersions may involve a time variation. An OTDM signal receiver (4) demultiplexes a transmission signal into low-speed optical signals, in a light region, receives optical pulses for respective channels and converts them into electric signals.

Abstract: Apparatus and methods for providing a drive laser beam to a communication unit responsive to the drive laser beam provide the communication unit the ability to provide femtosecond communication. In an embodiment, the communication unit may be configured as an emitter to provide an optical signal for multiplexing into a transmission medium. In an embodiment, the communication unit includes an a time lens in a configuration that provides separation of optical channel signals from a received optical signal and time expansion of each optical channel signal.

Abstract: A device and a method for converting WDM signals into an OTDM signal. A time shift is introduced between the pulses of the WDM signals carried by the optical carriers. A modulation means is (112, 113, 114) adapted to modify the optical power of the WDM signals, and an optical temporal multiplexer/ demultiplexer (120) is provided. The WDM signals are injected into a birefringent propagation medium (130) in such a manner as to achieve a soliton trapping phenomenon. An absorption means (140) is adapted to introduce optical losses into the components of the OTDM signal. This technique performs WDM/OTDM conversion at very high bit rates. It also performs OTDM/WDM conversion. It is intended to be installed in long-haul telecommunication networks.

Abstract: A ring connection system and method are providing for distributing signals in an optical-to-electrical interface. The method electrically connects a plurality of nodes in a series-connecting ring, and receives an optical signal at a first node from a service provider. The method converts the optical signal to an electrical signal, and distributes the electrical signal via the ring. At each node, the electrical signal is supplied from a customer interface. Typically, each node has a plurality of customer interfaces. In one aspect, ITU-T G.984.3 Giagbit-capable Passive Optical Network (GPON) optical signals are received converted to a customer interface electrical signal such as an Ethernet connecting transfer mode, or time division multiplexed signal. Electrically connecting the plurality of nodes in the series-connected ring includes: series connecting the nodes in a North ring; and, series connecting the nodes in a South ring, opposite in direction from the North ring.

Abstract: A tunable dispersion compensator in which a heater portion can be easily constructed to reduce cost. A tunable dispersion compensator includes: an optical fiber having a grating portion; a heating unit for heating the grating portion to apply a temperature distribution to the grating portion; and a control unit for controlling the temperature distribution applied by the heating unit to control the group delay time characteristic of the grating portion. The heating unit includes: a heater including a single conductor having electrical resistors and which extends in a longitudinal direction of the grating portion over at least the entire length of the grating portion; and wirings electrically connected with the heater in respective positions along the longitudinal direction. The control unit supplies a voltage to each of the wirings.

Abstract: The number of power amplifiers required to amplify a plurality of transmission signals is reduced by using non-linear transmission lines (NTL) circuits. In general, a “combining” NTL circuit is used to combine the plurality of transmission signals to form a soliton pulse. The soliton pulse is then amplified such that each of its component transmission signals are amplified. A “dividing” NTL circuit is then used to divide the amplified soliton pulse into its component amplified transmission signals. The amplified transmission signals can therefore be transmitted over a communications channel without requiring a separate power amplifier for each.

Abstract: A dispersion-managed optical soliton transmission system uses alternating spans of positive-dispersion optical fiber having a negative slope and negative-dispersion optical fiber having a positive slope. For wavelength division multiplexing, the system has a map strength preferably between 4 and 8. An absolute value of average group velocity dispersion between 0.5 and 0.0 ps2/km, and soliton power may vary between channels within 1 dB. Map periods, amplifier spacings, and dispersion values across a wavelength range of 1530–1600 nm are disclosed for bit rates of 10 and 40 Gbits/sec to maintain the ranges of average group velocity dispersion and soliton power.

Abstract: An optical transmission system which permits transmission distance to be prolonged without using repeaters and yet ensures economical, high-quality optical transmission. A branch station performs non-repeated communication with an optical branching point and includes a light pumping section for causing pump light to enter an optical fiber through which a branched, receiving optical signal flows, to perform optical amplification by using the fiber as an amplification medium. An optical branching device includes an optical amplification section and an optical branching section. The optical amplification section redirects the pump light originated from the branch station and propagated through a line to the paired line through which an optical signal transmitted from the branch station flows, to excite an amplification medium inserted in the paired line and doped with active material for optical amplification and thereby amplify power of the optical signal transmitted from the branch station.

Abstract: A soliton transmission method where groups of partially overlapping short pulses are sent as solitons. Such pulses are laser pulses or any other electromagnetic radiation pulses having a same wavelength. The pulses in the pulse groups can be modulated both individually as well as collectively as a group. The present invention introduces also data packets based on such pulse group solitons. It is also introduced a packet switching system for packet based networks, where the packets are switched according to delivery address predictions. In said packet switching system, the node computers boost the accuracy of the packet delivery address predictions by interleaving the switched packets so that their delivery addresses follow regular patterns in the relayed packet trains. In said packet switching system, it is also introduced two different switching methods which use packet tags to denote the delivery addresses of packets.

Abstract: The present invention relates to a method for processing an optical signal is provided. An optical signal is input into an optical waveguide structure for providing a nonlinear effect. As a result, the optical signal undergoes chirping induced by the nonlinear effect. An output optical signal output from the optical waveguide structure is supplied to an optical bandpass filter to thereby extract components except a small-chirp component from the output optical signal. The optical bandpass filter has a pass band including a wavelength different from the wavelength of the optical signal. By extracting the components except the small-chirp component from the output optical signal in the form of pulse, it is possible to remove intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse.

Abstract: The present invention relates to a method for regenerating an optical signal suitable for WDM (wavelength division multiplexing). In this method, an optical signal is supplied to an optical waveguide structure (e.g., optical fiber) for providing a nonlinear effect. As a result, the optical signal undergoes chirp induced by the nonlinear effect. Then, an output optical signal output from the optical waveguide structure is supplied to an optical filter to thereby remove a small-chirp component from the output optical signal. By removing the small-chirp component from the output optical signal in the form of pulse, intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse can be removed. Accordingly, the optical signal can be regenerated independently of the bit rate, pulse shape, etc. of the optical signal.

Abstract: A wavelength selective switch is realized by combining a quantized dispersion element and an array of switching means. The quantized dispersion element enables to concentrate all the wavelengths within predetermined wavelength bands onto the same location in the switching array. With this arrangement, a low fill factor switching array can be used while maintaining good flat-top spectral performance with no spectral dips and improving alignment tolerances.

Abstract: A network control system may be embodied in various elements of a communication network which communicates optical signals multiplexed by wavelength division multiplexing (WDM). In a preferred embodiment of the invention, the network control system limits a number of channel wavelengths actually used for communicating the optical signals to an end node to a highest number N of separable channel wavelengths at the end node. In another preferred embodiment of the invention, the network control system controls and modifies, as necessary, data rates carried over channel wavelengths multiplexed by WDM in order to reduce interference and improve performance of the communication network.

Abstract: Wavelength locked feedback loops are provided in frequency guide filters, and particularly in sliding frequency guide filters, wherein the wavelength locked feedback loop allows precise control over the location of the filter center wavelength with respect to a transmitted soliton center wavelength, compensating for factors such as the filter rolloff, signal spectral width, and changes in the transmission line properties due to temperature, microbending, aging and other effects. This approach allows the construction of very inexpensive frequency guiding filters, which can be based on low precision frequency domain filters with active compensation. These advantages make it possible to design new types of dispersion managed soliton optical transmission networks.