Abstract: A system and method is provided for minimizing power fluctuations and crosstalk in a wavelength division multiplexed optical (WDM) network employing dynamic add/drop techniques by utilizing amplifiers operating in a nearly linear region. Conventionally, erbium-doped fiber amplifiers (EDFAs) are operated in saturation for providing signal amplification in a WDM network. Instead of using saturated EDFAs, the present invention includes optical amplifiers operated in a linear or nearly linear regime for providing signal amplification in a dynamic add/drop or bursty data WDM network. By operating optical amplifiers in a linear or nearly linear regime, power fluctuations, transients and crosstalk caused by adding/dropping or switching channels in the WDM network are minimized. Raman amplifiers, EDFAs, or semiconductor optical amplifiers (SOAs) can all be operated in a linear or nearly linear range to provide linear amplification in such a dynamic add/drop or bursty data WDM network.

Abstract: A WDM transmission device includes a level adjustment unit adjusting levels of optical signals having different wavelengths, a multiplexer multiplexing the optical signals, an amplifier amplifying a multiplexed optical signal, and a monitor unit monitoring the multiplexed optical signal applied to the amplifier and a level of an output signal of the amplifier and controlling the level adjustment unit so that the levels of the optical signals fall within a predetermined level range in which the amplifier can operate normally.

Abstract: Even when wavelength number of input optical signals is changed, or when the optical signals are intermittently transmitted e.g. in the case of the optical packet signals, amplification with constant output intensities for respective wavelengths is provided. An optical amplifier of the invention comprises a semiconductor laser which outputs light having a constant intensity and a given wavelength &lgr; L, a semiconductor optical amplifier which amplifies part of the input optical signals and output light from the semiconductor laser, an optical filter which extracts only an optic element having a wavelength of &lgr; L among the output light therefrom, a means which provides a rare earth ion-doped optical fiber with other part of the input optical signals and the extracted optic element having a wavelength of &lgr; L.

Abstract: In one aspect of the invention, a system operable to reduce degradation of an optical signal to noise ratio where signals having multiple wavelengths are communicated over a common optical link includes an amplifier assembly operable to introduce to a lower communication band a first gain and to introduce to a higher communication band a second gain that is different from the first gain. In addition, the system is operable to introduce a variable gain tilt into at least one of the communication bands. The different gains introduced to the higher and lower bands and the variable gain tilt introduced into at least one of the bands result in a reduction of a degradation of optical signal to noise ratio that could otherwise be caused by wavelength dependent attenuation when the communication bands are combined and communicated over an optical link.

Abstract: The invention comprises a method and apparatus for passive optical conditioning and format conversion of RZ optical signals including, but not limited to, conversion from RZ to CRZ or to CSRZ, using a nonlinear device. The invention generates signals that may be optimized to improve transmission performance, receiver performance, and/or spectral efficiency of the optical transmission system. A method for passively generating an optical carrier-suppressed return-to-zero (CSRZ) signal according to the present invention includes, propagating an optical RZ signal through a nonlinear element, the nonlinear element configured to broaden the optical RZ signal such that the optical RZ signal is phase shifted by approximately 3Π/2.

Abstract: A method and devices for individually controlling the signal strength of single or multiple optical channels. A controller module monitors the signal strength of channels and amplifies those that need amplifying while attenuating those that are too strong using the same Erbium doped fiber amplifier. A controllable compensation module receives at least one channel and, when required, can either amplify or attenuate the signal strength of the channel(s). The module can be constructed out of a single fiber with an associated pump laser. If the laser provides insufficient pumping power, the fiber acts as an attenuator. If the laser provides a higher level of pump power, the fiber acts as an amplifier.

Abstract: A short pulse laser system uses dispersive optics in a chirped-beam amplification architecture to produce high peak power pulses and high peak intensities without the potential for intensity dependent damage to downstream optical components after amplification.

Abstract: An optical communications system, including first terminal equipment, second terminal equipment, third terminal equipment, a first powered optical segment connected to the first terminal equipment and including at least one amplifier, a second powered optical segment connected to the second terminal equipment and including at least one amplifier, an unpowered optical segment connected to the third terminal equipment, and a branch unit connecting the first powered segment, the second powered segment, and the unpowered segment via passive, all-optical connections, and wherein the unpowered segment is pumped with optical energy through the branch unit from at least one of the amplifiers in the first and second powered segments.

Abstract: The present invention relates to a method for optical fiber communication, and a terminal device and system for use in carrying out the method, and an object of the present invention is to compensate for chromatic dispersion and nonlinearity. A device for outputting an optical signal having a variable optical power into an optical fiber transmission line is provided. The optical signal transmitted by the transmission line is converted into an electrical signal by an optical receiver. A parameter related to waveform degradation of the electrical signal is detected by a monitor unit. A control unit controls the optical power of the optical signal to be output from the device so that the waveform degradation is improved.

Abstract: An optical transmission system is formed to include an optical phase conjugator at alternate repeater sites to minimize the presence of four-wave mixing and other Kerr effect nonlinearities in systems using optical fiber transmission paths (particularly in systems using DWDM and launching relatively high power signals into the low dispersion fiber). Raman gain is included in each fiber span (or in alternate fiber spans) so as to provide a “negative absorption” along the length of the fiber and thereby provide for essentially symmetrical power distribution along the length of each span, where the presence of such a symmetric,power distribution on each side of an optical phase conjugator has been found to significantly improve its performance.

Abstract: The bidirectional dispersion compensator comprises at least one circulator (Z,Z1,Z2,Z4) and at least one filter-coupler element (F1, etc.). The optical signals (S1,S2) that are emitted in opposite directions are merged and sent to a compensation fiber (LK,LK1, etc.) together, are reflected at the ends of this fiber, and are forwarded in the respective directions of transmission as dispersion-compensated optical signals (SK1 and SK2).

Abstract: The present invention has an object to provide a WDM optical transmission system for effectively compensating such as wavelength dispersions of respective wavelength bands, by a simple constitution making use of a hybrid transmission path in case of transmitting a broadband WDM signal light containing a plurality of wavelength bands. To this end, wavelength dispersion characteristics of a hybrid transmission path utilizing a 1.3 &mgr;m zero-dispersion SMF and an RDF in the present WDM optical transmission system, are set such that compensation ratios of wavelength dispersion and dispersion slope become approximately 100% for a reference wavelength band which is one of a plurality of wavelength bands; and dispersion compensation fibers capable of compensating wavelength dispersions caused within the hybrid transmission path are inserted into propagation paths, respectively, within an optical amplifier, for the wavelength bands except for the reference wavelength band.

Abstract: The invention relates to a method of reducing the intensity distortion induced by cross phase modulation in a wavelength division multiplexed optical fiber transmission system comprising a transmission line made up of a plurality of optical fiber segments with repeaters interposed between successive optical fiber segments, the transmission system having N different wavelength channels, where N is an integer greater than unity. In each repeater interconnecting first and second consecutive fiber segments, a time offset is introduced between the channels in such a manner that compared with the inlet of the first optical segment, the (n+1)th and the nth channels are offset by &tgr;n at the inlet to the second fiber segment, where n is an integer less than or equal to N, where &tgr;n is selected to be greater than zero and less than a value that eliminates correlation between the intensity distortion contributions of each fiber segment.

Abstract: A high-capacity optical transmission arrangement utilizing a plurality of laser sources and a plurality of wide-band optical amplifiers permit the reliable transmission of 1 Tb/sec rates over significant distances of optical fiber.