Abstract: A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

Abstract: A thermal nonlinear cell and method. The cell includes a substantially planar nonlinear medium and a mechanism for removing thermal energy from the medium in a direction substantially orthogonal to said medium. In one embodiment, the mechanism for removing thermal energy is a thermally conductive window mounted adjacent to the medium. Preferably, the mechanism includes plural thermally conductive windows between which the nonlinear medium is disposed. In the best mode, the windows are sapphire and the nonlinear medium is a fluid. The windows and the medium are transmissive with respect to first and second beams that interfere with each other and create an interference pattern in the cell. The interference pattern is sampled by a sampling hologram created within the multiple layers of the medium. The interference pattern is used via a sampling hologram to create a phase conjugate of a signal beam. The windows move thermal energy from the medium in a direction transverse to the longitudinal axis of the medium.

Abstract: A coherent laser beam combining system wherein the output of a single master oscillator is split into a plurality of signals, the signals are electronically modulated at unique frequencies. One signal is designated a reference signal while the remaining signals are passed through phase adjusters. All signals are optically amplified, aligned and passed through a beam splitter to split off a small sample that is imaged onto a photodetector. The photodetector output is fed to a signal processor that produces phase error signals that drive the phase adjusters resulting in a high-powered optically coherent output signal.

Abstract: A wideband erbium-doped optical fiber amplifier is disposed among an optical fiber through which a first and second band-band optical signals (for example, the C-band and L-band) are transmitted and forms a first optical path and a second optical path parallel to each other. The wideband erbium-doped optical fiber amplifier comprising a first amplifying section disposed on the first optical path, including a first erbium-doped optical fiber to amplify the first-band optical signals, a filter to gain-flatten the amplified first-band optical signals, wherein a reflected portion of the first band optical signal by the filter is directed to the second optical path; and a second amplifying section disposed on the second optical path, having a second erbium-doped optical fiber to amplify received second-band optical signals, wherein the reflected first-band optical signal is used to pump the second erbium-doped optical fiber.

Abstract: A method passively locks and phases an array of fiber amplifiers in a fiber amplifier system that emits a beam, such as a laser beam. The method locks the fiber amplifiers so that the fiber amplifiers operate at same or similar frequencies. The method samples a small portion of the emitted beam in a far-field around a central lobe on an optical axis and then couples this portion of emitted beam back into the array of fiber amplifiers. The fiber amplifiers may be phased so that the emitted beam concentrates its energy around the central lobe in the far-field. Phasing may be achieved by using an aperture, for example, to restrict the portion of the emitted beam to be coupled back to a restricted region around the optical axis.

Abstract: The optical amplifying device comprises a DFB laser 22 formed on an n type InP substrate 10, for outputting control light; a symmetrical Mach-Zehnder interferometer 12 formed on the n type InP substrate 10 and including 3 dB optical couplers 14, 16 having 2 input ports and 2 output ports, and optical waveguides 24a, 24b which optically interconnect the output port of the 3 dB optical coupler 14 and the input port of the 3 dB optical coupler 16; and SOAs 24a, 24b respectively formed in the optical waveguides 24a, 24b.

Abstract: In an optical amplifier of the invention, a WDM signal light is separated into N components by a demultiplexer after which each component is amplified by N optical amplifier sections, and the output light level of each optical amplifier section is controlled to a constant level by respective control circuits and multiplexed in a multiplexer. At this time, in the demultiplexer, the bandwidth of the signal light output from each of the output ports is designed to have a different value, so that inter-wavelength deviation in the optical output level that occurs in each of the optical amplifier sections, falls within a preset range. Moreover, the constant output control of each control circuit is performed by individually adjusting the gain of each of the optical amplifier sections in relation to fluctuations in the power level without channel number changes of the WDM signal light input to the demultiplexer.

Abstract: An optical amplifier (200) splits an optical signal into two signals (210, 212). A first amplifier section (202) receives the first signal (210). The first amplifier section (202) includes a first optical fiber (220), having a first input, for generating a first output power (230), and a first pump source (222) is coupled to the first input, for supplying a first energy amount to the first optical fiber (220). The optical amplifier (200) also includes a second amplifier section (204) to receive the second signal (212), which is arranged in parallel to, and under common control with, the first amplifier section (202). The second amplifier section (204) includes a second optical fiber (240), having a second input, for generating a second output power (250), and a second pump source (232) is coupled to the second input, for supplying a second energy amount to the second optical fiber (240). A total power (280) of the first output power (230) and the second output power (250) is at least about 600 mill Watts.

Abstract: The present invention aims at providing a method for controlling wavelength characteristics of optical transmission powers by Raman amplification, in which the wavelength characteristics of optical transmission powers are automatically compensated without giving any losses to channel lights to thereby improve transmission characteristics, and an apparatus adopting the same. To this end, the method for controlling wavelength characteristics of optical transmission powers by Raman amplification according to present invention supplies Raman pump light to an optical transmission path (Raman amplifying medium); compensates the wavelength characteristics of optical transmission powers caused by transmission of WDM signal light through the optical transmission path, by gain wavelength characteristics of generated Raman amplification; and monitors the wavelength characteristics of optical transmission powers after Raman amplification to thereby control the gain wavelength characteristics of Raman amplification.

Abstract: A number of nonlinear optical fibers are configured in a parallel configuration. The fibers are pumped with optical pumps having a wavelength slightly longer than the zero dispersion wavelength for each fiber. By a demultiplexer optical signals within a certain wavelength interval are admitted to enter and exit the different fibers, in which parametric amplification can be achieved. By selecting the pump wavelength outside each corresponding interval crosstalk will be suppressed. The nonlinear fibers can be pumped by separate laser pumps, or two or more of the nonlinear fibers can be pumped by a common pump, depending on the different fiber properties. By tailoring fiber properties such as the zero dispersion wavelength, the second order dispersion coefficient and the fourth order dispersion coefficient, beneficial amplification characteristics can be achieved in different wavelength intervals.

Abstract: A hybrid laser source including a solid state laser driven by an array of fiber laser amplifiers, the inputs of which are controllable in phase and polarization, to compensate for distortions that arise in the solid state laser, or to achieve desired output beam properties relating to direction or focus. The output beam is sampled and compared with a reference beam to obtain phase and polarization difference signals across the output beam cross section, at spatial positions corresponding with the positions of the fiber laser amplifiers providing input to the solid state laser. Therefore, phase and polarization properties of the output beam may be independently controlled by predistortion of these properties in the fiber laser amplifier inputs.

Abstract: A system for distributing optical signals comprises a plurality of optical splitter stages. The optical splitter stages are each operable to passively split each of one or more optical signals provided to the stage into a plurality of optical signals. At least one of the optional splitter stages comprises an amplification stage, with the amplification stage including a plurality of gain media. The gain media are each operable to amplify an optical signal with pump power.

Abstract: An optical communication system includes a plurality of optical channels, each of which passes a single optical wavelength signal. Each of the plurality of optical channels includes an optical amplifier which is controlled to operate at a predetermined output power level independent of channel wavelength and input power level by operating each optical amplifier in a saturation mode. Pumping power for operating each optical amplifier in the saturation mode is supplied from shared optical pumps or a plurality of one per channel optical pumps.

Abstract: Disclosed wideband optical fiber amplifier amplifies and outputs wideband optical signal containing C-band and L-band optical signals. The amplifier includes: a first amplification section amplifying the wideband optical signals; a second amplification section amplifying the separated L-band optical signals amplified by the first amplification section; an optical signal coupler combining and outputting the optical signals amplified by the first and second amplification sections; and an optical circulator.

Abstract: An electromagnetic radiation (EMR) multiple pulse generator, comprising, an EMR source for producing discrete pulses of radiation, an EMR splitter for receiving the pulses of radiation produced by the EMR source, said splitter providing a plurality of EMR transmission paths for the received pulses, each of said transmission paths having physical characteristics for modifying EMR pulses passing through said paths relative to the input pulses, an EMR combiner for combining the modified outputs of said plurality of EMR transmission paths, and at least one combined EMR output transmission path for transmitting said combined EMR output.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: The wideband optical fiber optical includes a circulator. In addition the amplifier outputs the amplified spontaneous emission (ASE) and the S-band optical signals. At least one optical fiber grating is used for passing the C- and L-band optical signals. A wavelength selective splitter outputs the L-band optical signal. A first optical fiber amplifying unit connected with the optical fiber grating and the first port of the wavelength selective splitter, for amplifying the C- and L-band optical signals and for outputting the ASE to the optical fiber grating. A second optical fiber amplifying unit for amplifying the L-band optical signals inputted from the second port of the wavelength selective splitter and for outputting the amplified L-band optical signals to the third terminal of the outputting unit.

Abstract: A dynamic gain equalizer using amplification instead of attenuation is disclosed. The device relies on integrated semiconductor optical amplifiers in line with a demultiplexer on a single integrated substrate for performing equalization of signals within each of a plurality of channels.

Abstract: An amplification architecture for WDM receiver systems. The WDM channel grid is divided into groups of adjacent channels. A separate optical amplifier is provided for each channel with a single pump being shared among the channels of each group. The gain experienced by channels of a given group may be adjusted by varying the power of the group's pump. This approach allows equalization of received channel power such that all channels fall within the desired dynamic range. The amplification architecture may be implemented in a space-efficient manner at low cost.

Abstract: An optical amplifier (200) splits an optical signal into two signals (210, 212). A first amplifier section (202) receives the first signal (210). The first amplifier section (202) includes a first optical fiber (220), having a first input, for generating a first output power (230), and a first pump source (222) is coupled to the first input, for supplying a first energy amount to the first optical fiber (220). The optical amplifier (200) also includes a second amplifier section (204) to receive the second signal (212), which is arranged in parallel to, and under common control with, the first amplifier section (202). The second amplifier section (204) includes a second optical fiber (240), having a second input, for generating a second output power (250), and a second pump source (232) is coupled to the second input, for supplying a second energy amount to the second optical fiber (240). A total power (280) of the first output power (230) and the second output power (250) is at least about 600 mill Watts.

Abstract: In an optical amplifier and a method thereof, and in particular to a wavelength division multiplexing system using a C-band optical signal and a L-band optical signal, by using a portion of a C-band optical signal filtered out during gain flattening as a pump optical signal for amplification of an L-band optical signal, optical components required by prior systems for providing a pump optical signal to an L-band optical signal amplifier are not required. Accordingly, the present invention reduces the number of required optical components. In addition, by using the portion of the C-band optical signal filtered out during gain flattening, energy usage efficiency is improved.

Abstract: A wide band erbium-doped fiber amplifier with a gain enhancement is provided comprising a first fiber amplifier adapted to amplify C-band components of an input optical signal, a second fiber amplifier connected to the first fiber amplifier in series while being disposed downstream from the first fiber amplifier to amplify L-band components of the input optical signal. A C/L splitter is disposed between the first and second fiber amplifiers and to split the amplified C and L-band optical signals to flow along different paths. A fiber reflector is disposed downstream from the second fiber amplifier to reflect the amplified L-band optical signal to flow backwards toward the second fiber amplifier. A circulator is disposed between the C/L splitter and the second fiber amplifier to guide the amplified L-band optical signal, reflected to flow backwards by the fiber reflector, so that the amplified L-band optical signal flows along a path different from that of optical signals applied to the circulator.

Abstract: A bi-directional optical transmission system according to the present invention provides transport of x optical channels over n nodes. The system supports two-way transport of the x channels over a single fiber connecting each of the nodes in sequence. The system is advantageous in that only two optical transmission bands are utilized in order to achieve minimal loss in the separation of bands. The use of only two bands permits the utilization of low-loss wide band thin film optical filters to combine and separate the signals at each node. A reflection port of this filter is used to carry oppositely directed signals of the second band from the bi-directional fiber to an optical amplifier for the second band. An alternate arrangement of the optical filters in the two separate bands is chosen to maximize the optical performance of the overall system and significantly reduce insertion losses.

Abstract: A wide band erbium-doped fiber amplifier with a gain enhancement is provided comprising a first fiber amplifier adapted to amplify C-band components of an input optical signal, a second fiber amplifier connected to the first fiber amplifier in series while being disposed downstream from the first fiber amplifier to amplify L-band components of the input optical signal. A C/L splitter is disposed between the first and second fiber amplifiers and to split the amplified C and L-band optical signals to flow along different paths. A fiber reflector is disposed downstream from the second fiber amplifier to reflect the amplified L-band optical signal to flow backwards toward the second fiber amplifier. A circulator is disposed between the C/L splitter and the second fiber amplifier to guide the amplified L-band optical signal, reflected to flow backwards by the fiber reflector, so that the amplified L-band optical signal flows along a path different from that of optical signals applied to the circulator.

Abstract: Disclosed is a wide band optical fiber amplifier for amplifying C and L-band optical signal components having an economical configuration, high amplification efficiency while exhibiting a low noise figure. The amplifier includes first and second isolators; first, second, and third amplification units; a distributor; a gain flattening filter; and first and second reflectors. The amplifier receives C and L band optical signals and process the signals by: amplifying C and L band signals; gain flattening the only C band signal twice; amplifying C and L band signals for the second time; splitting the C band signal from L band signal; subjecting L band signal to be amplified three more times; and combining resulting C and L band signals.

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

Abstract: An optical amplifier, or optical repeater, for amplifying wavelength division multiplexed (WDM) light. A first demultiplexer demultiplexes the WDM light into first and second lights corresponding to different wavelengths in the WDM light. First and second optical amplifiers amplify the first and second lights, respectively. A first multiplexer multiplexes the amplified first and second lights into a multiplexed light. A dispersion compensator compensates for dispersion in the multiplexed light. A second demultiplexer demultiplexes the dispersion compensated, multiplexed light into the first and second lights. Third and fourth optical amplifiers amplify the demultiplexed first and second lights, respectively. A second multiplexer multiplexes the amplified first and second lights from the third and fourth optical amplifiers into a WDM light. The optical amplifier can be configured so that the first and second lights travel through the dispersion compensator in opposite directions.

Abstract: A broadband optical amplifier is disclosed. The amplifier includes an input having a plurality of optical wavelengths, including optical wavelengths between 1610 and 1620 nanometers, and a first optical splitter optically connected to the input. The first optical splitter splits the input into a first band signal portion, a second band signal portion, and a third band signal portion. An amplifying portion is optically disposed along each of the first, second, and third band signal portions optically downstream from the first optical splitter. A first optical combiner is optically connected to the first, second, and third band signal portions to form an output. A method of amplifying a broadband optical signal is also disclosed.

Abstract: A measurement light (X) is introduced on either one of reflection surfaces (501, 502, 511, 512) to detect a returned light (Y) reflected by the reflection surfaces (501, 502, 511, 512), reflected by a reflecting device and again reflected by the reflection surfaces (501, 502, 511, 512) by an autocollimator (620) to conduct image-processing and calculation by a processor (628), where a position adjuster (690) adjusts an attitude of a cross dichroic prism (45) relative to a fixing plate (447) to eliminate deviation between a position of the measurement light (X) and the returned light (Y) based on the result of the processing, thereby producing a highly accurate prism unit (50).

Abstract: A modulator having a waveguide and a microdisk resonator is disclosed. The waveguide has an input port for receiving a light signal of wavelength ? and an output port for transmitting modulated light. The microdisk resonator has a resonance at ? and is coupled to the waveguide between the input and output ports such that at least 10 percent of the light traveling in the waveguide is coupled to the microdisk resonator. The microdisk resonator further includes a material having a first state and a second state, the material absorbing more of the light in the first state than in the second state. The first and second states are selectable by a signal that is applied to the microdisk resonator. In one embodiment, the waveguide and the microdisk resonator occupy different portions of a sheet of material having the various layers used to construct the resonator.

Abstract: The inventive fiber amplifier comprises: (a) a first Er-doped fiber provided with a first light-pumping source via a first pump combiner to amplify input optical signals; (b) a second Er-doped fiber provided with a second light-pumping source via a second pump combiner to amplify input L-band optical signals; (c) a C/L splitter provided in the downstream of the first Er-doped fiber for splitting the optical signals into C- and L-bands, respectively, during passage through the C/L splitter; (d) a reflector for transmitting the L-band optical signals split in the C/L splitter toward the second Er-doped fiber and reflecting the transmitted L-band optical signals to flow back toward the second Er-doped fiber; (e) a circulator for introducing the L-band optical signals which are amplified after backward flow from the reflector toward another direction and preventing the backward flow of ASE generated during amplification toward the first Er-doped fiber; and, (f) a C/L combiner for combining the C-band optical sign

Abstract: A source and/or method of generating quantum-correlated and/or entangled photon pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550 nm fiber-optic communication band and detected by a detection system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode. A generation rate>103 pairs/s is observed, a rate limited only by available detection electronics. The nonclassical nature of the photon correlations in the pairs is demonstrated. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks. The detection system also provides high rate of photon counting with negligible after pulsing and associated high quantum efficiency and also low dark count rate.

Abstract: A Raman amplifier for amplifying a wavelength division multiplexed (WDM) light including signal lights wavelength division multiplexed together. The amplifier includes an optical amplifying medium and a controller. The optical amplifying medium uses Raman amplification to amplify the WDM light in accordance with multiplexed pump lights of different wavelengths traveling through the optical amplifying medium. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The controller controls power of each pump light based on a wavelength characteristic of gain generated in the optical amplifying medium in the individual wavelength bands.

Abstract: A rare earth element doped fiber forming an optical amplifier is pumped with a plurality of pumping lights to prevent drop of the inversion population ratio in the length direction of the rare earth element doped fiber.

Abstract: An optical amplifier is provided for performing amplification of optical signals of two wavelength bands, where deterioration in the optical SN ratio relative to one wavelength band is reduced, with a simple construction which can deal with restrictions on installation space, power consumption and the like. To this end, the present optical amplifier has a C/L band optical amplifying section for amplifying respective optical signals of a C band and an L band, a demultiplexer for demultiplexing output light from the C/L band optical amplifying section into the C band and the L band, an L band optical amplifying section for amplifying L band optical signals which have been demultiplexed by the demultiplexer, and a multiplexer for multiplexing the C band optical signals which have been demultiplexed by the demultiplexer and the L band optical signals which have been amplified by the L band optical amplifying section.

Abstract: An erbium-doped fiber amplifier and a wavelength division multiplexing optical transmission system equipped with the same are disclosed. The wavelength division multiplexing optical transmission system includes a transmission stage having a first C/L fiber amplifier for amplifying combined C and L-band optical signals, an optical repeater having at least one second C/L fiber amplifier for amplifying the optical signals transmitted from a single mode fiber of a predetermined length, and a dispersion compensating fiber of a predetermined length for compensating dispersions of the amplified optical signals. The system also includes a reception stage having a third C/L fiber amplifier for amplifying the optical signals transmitted from a single mode fiber of a predetermined length, and a receiver for separating the amplified optical signals from the third C/L fiber amplifier into C-band optical signals and L-band optical signals band by band and de-multiplexing the separated amplified optical signals.

Abstract: In order to obtain optical transmission equipment for wavelength division multiplexing for providing a small inter-wavelength deviation regardless of a change in an input level, an amplification band is divided with wavelengths at inflection points in a wavelength gain characteristic of an impurity-doped fiber. The equipment includes an optical filter unit and a optical gain adjusting unit. The optical filter unit obtains filter characteristics associated with wavelength gain characteristics for a plurality of input levels by changing a temperature thereof. The optical gain adjusting unit includes a wavelength gain characteristic shift filter having a Peltier element for controlling the temperate of the optical filter unit.

Abstract: The invention concerns an apparatus and a system for the transfer of optical data between satellites, which encompasses a laser oscillator (10) for generating an optical signal, a modulator (11) for modulating the optical signal with data information, and an amplifier assemblage, a collimator assemblage, and a transmission device for transfer of the signals. Provision is made for a preamplifier (12) to be connected to a power divider section (13) downstream from which is a parallel circuit of at least two phase shifters (14) and main amplifiers (15), respectively connected in series, for amplification and adjustment of the optical signals; and for the main amplifiers (15) to be connected, via a bundle (16) of optical waveguides corresponding to the number of series circuit(s), to the corresponding number of collimators (17).

Abstract: Dependence on wavelength makes it difficult to lengthen the distance while increasing the density of wavelength division multiplexing. An optical signal expander module for a group of wavelength bands in a transmission system is provided and configured to solve the problem of dispersion and to achieve both a longer distance and higher density of wavelength division multiplexing that can be traded off.

Abstract: In a method and system for evaluating distributed gain in an optical transmission system, a data signal and a residual pump laser signal propagating in opposite directions within a waveguide are monitored. Modulation of the residual pump laser signal is correlated with low frequency components of the data signal. This correlation is used to determine cross-talk between the data signal pump laser signals, as a function of location within the waveguide. The distributed gain is then evaluated from the cross-talk, using a known relationship, or proportionality, between gain and cross-talk.

Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.

Abstract: A wideband erbium-doped optical fiber amplifier is disposed among an optical fiber through which a first and second band-band optical signals (for example, the C-band and L-band) are transmitted and forms a first optical path and a second optical path parallel to each other. The wideband erbium-doped optical fiber amplifier comprising a first amplifying section disposed on the first optical path, including a first erbium-doped optical fiber to amplify the first-band optical signals, a filter to gain-flatten the amplified first-band optical signals, wherein a reflected portion of the first band optical signal by the filter is directed to the second optical path; and a second amplifying section disposed on the second optical path, having a second erbium-doped optical fiber to amplify received second-band optical signals, wherein the reflected first-band optical signal is used to pump the second erbium-doped optical fiber.

Abstract: A wideband optical fiber amplifier that can amplify S-band optical signals, C-band optical signals and L-band optical signals. The wideband optical fiber amplifier includes a circulator for outputting optical signals inputted into a first port thereof to a second port thereof. In addition the amplifier outputs the amplified spontaneous emission (ASE) and the S-band optical signals inputted from the second port thereof to a third port. At least one optical fiber grating is used for passing the C- and L-band optical signals from among the optical signals outputted from the second port of the circulator, and for reflecting the S-band optical signals back to the second port of the circulator. The ASE is then input from an interior of the optical fiber grating to the second port of the circulator. An output unit outputs optical signals inputted into first to third terminals thereof to a fourth terminal thereof.

Abstract: Disclosed is a wide-band fiber amplifier for amplifying C-band and L-band optical signals, including a first amplifying unit including a first amplifying fiber adapted to be (1) pumped in at least one direction (2) amplify both the C-band and L-band optical signals and (3) output Amplified Spontaneous Emission (ASE), a second amplifying unit including a second amplifying fiber adapted to be pumped by amplified ASE and secondarily amplify the amplified L-band optical signal, and an L-band pumping light source including a third amplifying fiber adapted to be pumped in at least one direction while being pumped by the ASE, and output amplified ASE used to pump the second amplifying fiber.

Abstract: Disclosed is a gain-controllable wideband optical fiber amplifier for amplifying both C-band and L-band optical signals, which comprises: a first amplifying section configured to (1) be pumped in at least one direction, (2) amplify both C-band and L-band optical signals and (3) output an amplified spontaneous emission; an optical attenuator for attenuating the power of the spontaneous emission; and a second amplifying section pumped by the attenuated spontaneous emission to secondarily amplify the amplified L-band optical signals.

Abstract: A fiber optic phased array, as well as associated methods and apparatus for controllably adjusting the frequency of the optical signals emitted by a fiber optic phased array, are provided that permit wide band phase control and may be implemented utilizing conventional analog electronics. In this regard, the method and apparatus can independently control the phase of the optical signals propagating through each fiber optic amplifier of the fiber optic phased array, even as large optical phase disturbances occur. As such, the control method and apparatus permit a fiber optic phased array to generate a flat phase front that, in turn, can provide a diffraction limited output laser beam. Alternatively, the control method and apparatus may be designed such that the output signals emitted by an array of fiber optic amplifiers has any other desired phase front, such as to compensate for atmospheric perturbations or the like.

Abstract: A signal may be split by a splitter into a plurality of output signals. Each of these output signals may then be amplified. Amplified spontaneous emission noise may be removed using a tunable filter for each of the signal outputs. As a result, an output signal may be provided with greater power so that, in some embodiments, a single split signal may be utilized to service more end users.

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: A projection exposure system is proposed which is positionable between a first object and a second object for imaging the first object in a region of the second object with light of a wavelength band having a width &dgr;&lgr; about a central working wavelength &lgr;, wherein a relative width &dgr;&lgr;/&lgr; of the wavelength band is larger than 0.002, in particular, larger than 0.005, for example, of the Hg-I-line. The projection exposure system is a so-called three-bulge system comprising three bulges having, as a whole, a positive refractive power and two waists having, as a whole, a negative refractive power. By applying suitable measures, in particular, by suitably selecting the material for the lenses forming the projection exposure system, the long-term stability of the system is increased.

Abstract: A cube used to perform optical functions in a system, such as beam splitting or polarizing, or both, is manufactured by optically contacting a coated prism with an uncoated prism. The coated prism includes a dielectric stack having alternating layers of high and low index of refraction materials. To ensure secure optical contacting between the coated prism and uncoated prism, low interface reflection, and good throughput, a contacting layer is deposited on the dielectric stack. The contacting layer can be fused silica or SiO2, which has natural compatibility with the CaF2 materials that make up the uncoated prism and the coating layers.