Abstract: Disclosed is an amplifying optical fiber having a central core and an optical cladding surrounding the central core. The central core is based on a silica matrix that includes nanoparticles, which are composed of a matrix material that includes doping ions of at least one rare earth element. The amplifying optical fiber can be employed, for example, in an optical amplifier and an optical laser.

Abstract: The present invention provides a rare earth element-doped optical fiber amplifier having a function which allows to omit an optical isolator component, and a method for providing the optical non-reciprocity using the same. In the optical fiber, the optical fiber matrix material is a ferroelectric solid state material, and the ferroelectric solid state material is doped by a rare earth element such as erbium (Er) or thulium (Tm). The optical fiber is characterized by an optical amplification function and an optical non-reciprocity function.

Abstract: A laser amplifier includes a pump source and an optically active fiber having an input portion configured to receive a signal source and an output portion. The pump source is optically coupled to the optically active fiber. The laser amplifier also includes an output fiber optically coupled to the output portion of the optically active fiber. The output fiber includes a rare-earth element. The laser amplifier further includes a beam expansion section joined to the output fiber.

Abstract: A small-sized, highly efficient optical amplifier having a PLZT optical waveguide layer to which a rare earth element is added, and a method for manufacturing the same are provided. Disclosed is an optical amplifier including an optical waveguide layer, the optical waveguide layer including Pb1-xLax(ZryTi1-y)1-x/4 O3 (PLZT: 0<x<0.3, 0<y<1.0), being doped with Yb (ytterbium) in an amount of from 0.2 mol % to 11.0 mol %, and being a single crystal film formed by solid-phase epitaxial growth.

Abstract: The invention describes techniques for the control of the spatial as well as spectral beam quality of multi-mode fiber amplification of high peak power pulses as well as using such a configuration to replace the present diode-pumped, Neodynium based sources. Perfect spatial beam-quality can be ensured by exciting the fundamental mode in the multi-mode fibers with appropriate mode-matching optics and techniques. The loss of spatial beam-quality in the multi-mode fibers along the fiber length can be minimized by using multi-mode fibers with large cladding diameters. Near diffraction-limited coherent multi-mode amplifiers can be conveniently cladding pumped, allowing for the generation of high average power. Moreover, the polarization state in the multi-mode fiber amplifiers can be preserved by implementing multi-mode fibers with stress producing regions or elliptical fiber cores These lasers find application as a general replacement of Nd: based lasers, especially Nd:YAG lasers.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers. After amplification, the dispersively stretched pulses can be re-compressed to nearly their bandwidth limit by the implementation of another set of dispersive delay lines.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Peak power handling capability of the fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Peak power handling capability of the fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers.

Abstract: A laser radar system and a method for use in a laser radar system are disclosed. More particularly, the laser radar system includes a fiber laser capable of generating a laser signal; a first optical path through which the generated laser signal may be transmitted; a second optical path through which a reflection of the transmitted laser signal may be received; and a detector capable of detecting the received reflection. The method includes generating a laser signal from a fiber laser; transmitting the laser signal; receiving a reflection of the transmitted laser signal; and detecting the reflection.

Abstract: An optical amplifier configuration for WDM (wavelength division multiplex) systems uses a common pump source connected to an input of an optical splitter deploying pump light via variable optical attenuators to a plurality of optical amplifiers. Control circuits determine individually the output powers of the amplifiers by varying the attenuations of the variable optical attenuators. Amplifier units based on PLC technology are implemented to reduce the size.

Abstract: A large mode area fiber amplifier suitable for high power applications includes a core region specifically configured to allow for high power operation while also limiting the amount of SBS that is generated. The composition of the core region is selected to include a dopant (such as aluminum) in selected areas to reduce the acoustic refractive index of the core and limit the spatial overlap between the acoustic and optical fields. The acoustic refractive index is also structured so that the acoustic field is refracted away from the central core area. In one embodiment, the core may comprise a depressed index center portion and surrounding ring core area, with the center portion including the aluminum doping and the ring formed to have a diameter less that the phonon decay length for the operating wavelength(s).

Abstract: The present invention relates to an optical amplifier module, or the like, having a structure for enabling effective suppression of photodarkening and efficient optical amplification. The optical amplifier module comprises a first optical amplification waveguide which is comprised of a phosphate glass as a main component and includes a ytterbium-doped first optical waveguide region, a second optical amplification waveguide which is optically coupled to the first optical amplification waveguide and includes a ytterbium-doped second optical waveguide region which is co-doped with aluminum, and pumping light source units which supply pumping light respectively to the first optical amplification waveguide and the second optical amplification waveguide. The light to be amplified, having inputted to the first optical amplification waveguide, is amplified only once by means of the pumping light, in each of the first optical amplification waveguide and the second optical amplification waveguide.

Abstract: An optical fiber amplifier apparatus and optical signal amplification method are provided. In one example, the amplifier apparatus comprises an optical combiner that is configured to receive an input optical signal to be amplified and a pump light beam. The optical combiner combines for output the input optical signal and the pump light beam. A first cladding pumped optical fiber in which Erbium is the only optically active dopant is coupled to the optical combiner to receive the pump light beam and the input optical signal. The first cladding pumped optical fiber pre-amplifies the input optical signal and passes the pre-amplified input optical signal and power of the pump light beam not absorbed by the first cladding pumped optical fiber. A second cladding pumped optical fiber is provided that is coupled to the first cladding pumped optical fiber. Erbium and Ytterbium are optically active dopants in the second cladding pumped optical fiber.

Abstract: A composite optic fibre for laser includes a core surrounded with a pump guiding sheath in contact with the core, sheath being a photonic structure formed by a substantially regular matrix assembly of coaxial capillaries, spaced apart and arranged parallel to the core, the core being a material with doping elements which may be brought into at least one excited electronic state by absorbing the energy from a pump optical signal of a first determined wavelength running through the core and capable of giving-back the former by de-energization in the form of an optical signal of a second determined wavelength, the core having a determined diameter and the sheath having a determined diameter. The diameter of the guiding sheath is greater than the core diameter and smaller than or equal to four times the core diameter, the core diameter being greater than or equal to 35 micrometers.

Abstract: An optical amplifier for amplifying an optical signal (1002), the optical amplifier comprising: an optical fibre, the optical fibre including a doped core, an inner cladding extending substantially radially outwardly from the doped core and an outer cladding extending substantially radially outwardly from the inner cladding; a signal coupler for receiving the optical signal and guiding the optical signal into the doped core; a first pump light source for producing a first pump light having a first power, the first pump light source being optically coupled to the optical fibre at a first location therealong for guiding the first pump light into the inner cladding at the first location; and a second pump light source for producing a second pump light having a second power, the second power being larger than the first power, the second pump light source being optically coupled to the optical fibre at a second location therealong for guiding the second pump light into the inner cladding at the second location; wh

Abstract: The present invention relates to a technique for tuning the transmission time of optical signal, which adopts an optical amplifier with a bending structure for enhancing the tunable time of optical signal. The effect of tunable time of optical signal can be achieved by adjusting the gain of the optical amplifier.

Abstract: An optical amplifier includes a rare-earth doped optical fiber or rare-earth doped optical waveguide serving as an amplification medium where rare-earth ions have been doped in its core and/or clad, an excitation mechanism for exciting the amplification medium, and a plurality of optical resonator that causes laser oscillation at a plurality of wavelengths of amplified spontaneous emission light produced in the amplification medium.

Abstract: A multi-channel optical amplifier arrangement operating over a particular bandwidth is provided. The amplifier arrangement includes at least one optical amplifier stage that includes a rare-earth doped optical waveguide, at least one pump source for supplying optical pump energy to the doped optical waveguide, and at least one coupler for coupling the optical pump energy to the doped optical waveguide. The amplifier arrangement also includes a dynamic range enhancer (DRE) having an input and an output and a plurality of distinct optical paths each selectively coupling the input to the output. At least two of the optical paths produce different gain spectra across the particular operating bandwidth. The DRE further includes an optical path selector for selecting any optical path from among the plurality of optical paths such that for all channels in the particular bandwidth the selected path optically couples the input to the output of the DRE.

Abstract: An amplifier optical fiber comprising a central core of a dielectric matrix doped with at least one element ensuring the amplification of an optical signal transmitted in the fiber and a cladding surrounding the central core and suitable for confining the optical signal transmitted in the core. The fiber also comprises metallic nanostructures suitable for generating an electronic surface resonance in the dielectric matrix of central core, the wavelength of said electronic surface resonance corresponding to an excitation level of the element ensuring the amplification.

Abstract: The present invention relates to an optical amplification module having a construction which effectively suppresses photodarkening, and to a laser light source including the same. The laser light source comprises a light source for outputting light to be amplified, and an optical amplification module. The optical amplification module comprises two types of optical amplification media having different rare earth element concentrations, and a pumping light source. The low concentration medium and the high concentration medium are disposed in the propagation direction of pumping light such that the population inversion of the low concentration medium is higher than that of the high concentration medium.

Abstract: The present invention relates to an optical amplifier and the like having a flatter gain spectrum in the wavelength band of 1490 nm to 1520 nm than before. The optical amplifier according to the present invention comprises an Er-doped optical waveguide and a Tm-doped optical waveguide having gain spectra difference from each other in the wavelength band. The signal light entered through the input end is first amplified by the Er-doped optical waveguide, and thereafter is amplified by the Tm-doped optical waveguide. The gain deviation of the amplified signal light, which has been amplified in the Er- and Tm-doped optical waveguides and outputted through the output end, can be reduced over the wavelength band.

Abstract: Provided is an erbium doped optical fiber (EDF) for amplification which allows an easy estimation of the amplification performance and high production stability. The fiber includes a core and a cladding. The core is mainly made of silica glass and doped with erbium at a concentration of 500 wtppm or more and 2500 wtppm or less. In the fiber, the cutoff wavelength is 850 nm or more and 1450 nm or less, the mode field diameter is 4.5 ?m or more and 6.5 ?m or less, the polarization mode dispersion is not more than 0.1 ps per 10 m, the coordination number of oxygen elements around an erbium element in the core is one or more and eight or less, and the bond length between erbium and oxygen is 0.225 nm or more and 0.235 or less.

Abstract: An optical amplifier that is configured to amplify multiple optical signals using time-multiplexed optical energy pulses. The time-multiplexed optical energy pulses are supplied to multiple gain blocks of the optical amplifier in an alternating manner and each of the gain blocks uses the optical energy pulses that it receives to amplify one of the multiple optical signals. An optical amplifier may be configured with an optical switch to perform a switching function to direct the time-multiplexed optical energy pulses received from the pump laser to the gain blocks in an alternating manner. The total optical energy contained in each optical energy pulse may be independently controlled by varying its duty cycle or amplitude.

Abstract: A first step, in which P2O5-containing glass is deposited inside a silica glass pipe, and a second step, in which a Cl2-containing gas is introduced into the pipe and the P2O5-containing glass is dehydrated by heating the pipe, are repeated alternately. A third step, in which glass that does not contain P2O5 is deposited on the inside of the silica glass pipe, may further be provided such that the first step, the second step, and the third step are repeatedly performed in this order. A rare-earth-doped optical fiber, which has a attenuation of 15 dB/km or less at a wavelength of 1200 nm, comprises a core region and a cladding region enclosing the core region, wherein the core region includes phosphorus of 3 wt % or more, aluminum of 0.3 wt % or more, a rare-earth element of 500 wtppm or more, and chlorine of 0.03 wt % or more, and the cladding region has a refractive index that is lower than the refractive index of the core region.

Abstract: The present invention provides a neodymium doped, transparent electro-optic gain ceramic material consisting lead, zirconium, titanium and lanthanum. The electro-optic gain ceramic material either has a linear electro-optic coefficient or a quadratic electro-optic coefficient, which is greater than about 0.3×10?16 m2/V2 for the latter, a propagation loss of less than about 0.3 dB/mm, and an optical gain of great than 2 dB/mm at a wavelength of about 1064 nm while optically pumped by a 2 watts diode laser at a wavelength of 802 nm at 20° C. The present invention also provides electro-optic devices including a neodymium doped, transparent electro-optic gain ceramic material consisting lead, zirconium, titanium and lanthanum. The present invention also provides lossless optical devices and amplifiers with an operating wavelength in the range of 1040 nm to 1100 nm while optically pumped at a wavelength in the range of 794 nm to 810 nm.

Abstract: Provided are a tellurite glass composite, an optical waveguide, and an optical amplifier using the tellurite glass composite. The tellurite glass composite includes an entire composite including 25 (mol %)?TeO2?90 (mol %), 1 (mol %)?T1O3?55 (mol %) or 1 (mol %)?T2O3?40 (mol %), 0 (mol %)?ZnO?35 (mol %), 0 (mol %)?M2O?35 (mol %), and 0 (mol %)?Bi2O3?20 (mol %). Here, T1 includes a transition metal Mo, T2 includes a transition metal W, M2O includes Li2O, Na2O, or two or more of Li2O, Na2O, K2O, Rb2O, and Cs2O including metals having +1 valence electrons, and amounts of M2O and ZnO are not simultaneously “0”.

Abstract: [Task] To provide the THz wave generator restricting increase in manufacturing cost or large size of the entirety of the apparatus and generating efficiently the several-W THz wave. [Means for Resolution] In a THz wave generator for generating a THz wave from a THz wave generating element by inputting a plurality of laser beams having different wavelengths to the THz wave generating element, at least one laser beam among the plurality of laser beams is formed into a pulse beam by the pulse generator and the pulse beam is amplified by an optical amplifier E and then the pulse beam is inputted to the THz wave generating element F. Preferably, the plurality of laser beams having different wavelengths are generated by inputting single wavelength beam to a multi wavelength generator from single mode laser light source and by inputting light waves having a plurality of wavelengths generated from the multi wavelength generator to wavelength selecting means.

Abstract: Provided is an all-optical gain-clamped fiber amplifier, comprising transmission and isolation means for periodically transmitting an optical signal or reflecting amplified spontaneous emission (ASE) back to a gain medium. The transmission and isolation means can be embodied by an optical interleaver or a number of optical fiber Bragg gratings. Accordingly, an optical signal can be amplified across the entire C-band, and an ASE reflector-based gain-clamped fiber amplifier having a wider dynamic range than conventional amplifiers can be implemented.

Abstract: An optical amplifier includes a rare-earth doped optical fiber or rare-earth doped optical waveguide serving as an amplification medium where rare-earth ions have been doped in its core and/or clad, an excitation mechanism for exciting the amplification medium, an optical resonator that causes laser oscillation at one or more wavelength of spontaneous emission light produced and amplified in the amplification medium, a monitoring mechanism that monitors a power of at least one light selected from a power of at least one light with at least one prescribed wavelength band selected from the light inputted to the amplification medium and a power of at least one light selected from a power of at least one light with at least one prescribed wavelength band selected from the light outputted from the amplification medium, and a control unit that controls the excitation mechanism based on a value from monitoring mechanism.

Abstract: An optical fiber amplifier pumping technique based on multiple stimulated Raman scattering (SRS) for optical communication systems includes a plurality of pump signals with increasing wavelength which are injected into a fiber. The wavelengths of such pump signals are such that, in cascade, each pump signal of the plurality is amplified by the pump signal of wavelength immediately shorter, while it amplifies that with the wavelength immediately higher with the pump signal of highest wavelength which, in turn, pumps a remote rare earth doped optical fiber amplifier.

Abstract: An optical fiber amplifier system is described and comprises a first optical fiber having a doped core with a first gain spectral profile upon being pumped. The first optical fiber is adapted to receive an optical signal from a light source. A second optical fiber has a doped core with a second gain spectral profile upon being pumped. The second optical fiber is optically coupled to the first optical fiber. A continuous wave pump light system is optically coupled to the fibers so as to store energy in the fibers for a subsequent amplification of the optical signal from the light source. An overlapping configuration is provided between the first gain spectral profile and the second gain spectral profile so as to reduce energy depletion in one of the optical fibers from amplification of spontaneous emission generated by another of the optical fibers.

Abstract: The present invention relates to an optical amplification module having a construction which effectively suppresses photodarkening, and to a laser light source including the same. The laser light source comprises a light source for outputting light to be amplified, and an optical amplification module. The optical amplification module comprises two types of optical amplification media having different rare earth element concentrations, and a pumping light source. The low concentration medium and the high concentration medium are disposed in the propagation direction of pumping light such that the population inversion of the low concentration medium is higher than that of the high concentration medium.

Abstract: Provided is an optical fiber for amplification and an optical fiber amplifier for use in L-band, in which optical fiber the increase of transmission loss and the degradation of hydrogen-resistant characteristic can be restrained. The optical fiber is basically made of silica glass and comprises: a core region doped with erbium and P element of 2 wt % to 5 wt % concentration, Ge not being added thereto; and a cladding region enclosing the core region and doped with F element, wherein the optical fiber has a gain at least in a wavelength range of 1570 to 1620 nm. The optical fiber amplifier comprises: the optical fiber; a pump light source for outputting the pump light capable of exciting a rare-earth element added to the core region of the optical fiber; and an optical coupler for introducing into the optical fiber the pump light having been output from the pump light source.

Abstract: A change in loading conditions of fiber amplifiers in an optical communications network causes rapid variations in the gain profile of the amplifiers due to spectral hole burning and stimulated Raman scattering. An apparatus for reducing such gain profile variations is described which monitors optical signal perturbations and reacts by adjusting pump powers of the amplifiers and, or fast variable optical attenuator according to a predetermined function stored in the form of constants in controller's memory. The optical signal is monitored as total power, and the power of light after passing through one or more optical filters. The light detection is relatively fast, whereby the gain profile variations are compensated by fast controlled variable optical attenuator and pump power adjustment upon the change in loading conditions.

Abstract: Conventional glass compositions including bismuth as a fluorescent element have a broad amplification wavelength region but do not allow the emission intensity in the 1.3-?m range to be sufficiently high through the excitation caused by light in the 0.8-?m and 0.98-?m ranges. The present invention provides a glass composition including: bismuth; a glass network former; and at least one element selected from the group consisting of dysprosium, erbium, ytterbium, neodymium, thulium, holmium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and molybdenum (except for tetravalent titanium and trivalent iron), wherein the glass composition emits fluorescence in an infrared wavelength region, with the bismuth functioning as a fluorescent source through irradiation of excitation light. The emission intensity is increased by the sensitization effect of the at least one element.

Abstract: The present invention provides a rare earth element-doped optical fiber amplifier having a function which allows to omit an optical isolator component, and a method for providing the optical non-reciprocity using the same. In the optical fiber, the optical fiber matrix material is a ferroelectric solid state material, and the ferroelectric solid state material is doped by a rare earth element such as erbium (Er) or thulium (Tm). The optical fiber is characterized by an optical amplification function and an optical non-reciprocity function.

Abstract: An all-fiber chirped pulse amplification (CPA) system and method is provided that utilizes a hollow core photonic bandgap fiber as a pulse compressor and a dispersion compensating optical fiber as a pulse stretcher that are matched with respect to both the amount and slope of dispersion to avoid peak power-limiting pulse distortion. The CPA system includes a rare earth ion-doped optical fiber amplifier having an input and an output that amplifies optical pulses having a center wavelength of ?c, a pulse compressing length L1 of hollow core photonic bandgap fiber having a dispersion value D1 and a dispersion slope S1 that varies over a wavelength ? of the pulses that is optically connected to the output of the fiber amplifier and having a k-parameter defined by a ratio of D1 over the slope of the function D1(?) that is larger than about 50, and a pulse stretching length L2 of dispersion compensating optical fiber connected to the input of the fiber amplifier having a dispersion value D2 and dispersion slope S2.

Abstract: A transmission fibre with optical amplification, comprising a core and a cladding. The core material is doped with a first dopant of a material having a higher index of refraction than the material of the cladding and with a second dopant of a material that converts pump energy in the form of light having a first wavelength into light having a second wavelength. The concentration of the second dopant within the core increases in radial direction in proportion to the distance to the centre of the core. The core material is preferably doped with a third dopant for compensating the variation in the refractive index caused by the second dopant. The cladding may comprise a cladding layer surrounding the core provided with a fourth and a fifth dopant for signal amplification and refractive index compensation, respectively, in the cladding layer. The dopants have been selected to enable amplification, using the Raman effect or stimulated emission.

Abstract: An optical amplifier on a silicon platform includes a first doped device layer and a second doped device layer. A gain medium is positioned between the first and second doped device layers. The gain medium comprises extrinsic gain materials so as to substantially confine in the gain medium a light signal and allow the optical amplifier to be electrically or optically pumped.

Abstract: A germanate glass composition suitable for use in a fiber amplifier for broadband amplification of optical signals is provided. The glass preferably includes 35-75% GeO2, 0-45% PbO, 5-20% BaO, 5-20% ZnO, and 2-10% R2O (R=Na, Li, K). It is doped with thulium ions (Tm3+) and codoped with holmium ions (Ho3+). The glass composition of the invention results in a remarkably large bandwidth as compared with previous glasses. It is also highly compatible with existing silica optical fibers.

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: A chirped-pulse fiber amplification method and system operates with large nonlinear phase shifts (as large as ˜20? or more). In this regime, the pulse spectrum is modified by strong self-phase modulation and gain shaping. With large-enough nonlinear phase shift, substantial spectral broadening occurs. The amplified spectrum can therefore be much broader than the spectrum that is obtained with small nonlinear phase shifts. The broader spectrum enables the formation of a shorter pulse, and the bandwidth generated in nonlinear chirped-pulse amplification can in fact be exploited to generate shorter pulses. Ultimately, this allows the generation of pulses shorter than the gain-narrowing limit of a fiber amplifier.

Abstract: By optimizing the refractive index profile, the absorption coefficient of a rare earth element doped optical fiber can be enlarged and nonlinear effect can be suppressed. Thus, according to the present invention, the optical fiber, which is suitable for wide band optical amplification, can be realized. Moreover, in the present invention, the optical fiber of W-shape profile comprising a core, the first cladding having a refractive index smaller than that of said core surrounding said core, and the second cladding having a refractive index smaller than that of said core and larger than that of said first cladding surrounding said first cladding is prepared and are suitable for the wide band optical amplification.

Abstract: In one aspect, an optical amplifier including a pump module, preferably for amplifying channels of a WDM-signal is provided. The outlet thereof is connected to an amplifying fibre wherein signal radiation formed by optical signals is amplified. In order to amplify the optical signals with minimum gain spectrum difference, i.e. in the WDM-technique with minimal channel level differences, pump radiation emerging from the pump module has a mode field diameter in the amplification fibre which is selected so that it is smaller than a mode field diameter of the signal radiation.

Abstract: Provided is an optical fiber. The optical fiber includes a core and a cladding, the core containing a first element for inducing non-linear Raman phenomenon, and the cladding containing a second element which is a rare earth element, wherein when the optical fiber is pumped by two pumping light sources having different wavelengths with each other, the optical signals in the first and third band are Raman-amplified by the first element and the signals in the second band are amplified by a direct transition of the second element.

Abstract: The present invention relates to an optical fiber for an optical amplifier and a method for manufacturing the same, which can be applied to an optical transmission system in the S-band area (4130 nm-1530 nm). According to the present invention, silica is used as a base material and the optical fiber for an optical amplifier contains Tm3+ ions and metal ions in a first core layer formed on an inner surface of a second core layer using the MCVD (Modified Chemical Vapor Deposition) method and a solution doping method whereby the practicability and productivity of the optical fiber are remarkably improved.

Abstract: A method and apparatus use a photonic-crystal fiber having a very large core while maintaining a single transverse mode. In some fiber lasers and amplifiers having large cores problems exist related to energy being generated at multiple-modes (i.e., polygamy), and of mode hopping (i.e., promiscuity) due to limited control of energy levels and fluctuations. The problems of multiple-modes and mode hopping result from the use of large-diameter waveguides, and are addressed by the invention. This is especially true in lasers using large amounts of energy (i.e., lasers in the one-megawatt or more range). By using multiple small waveguides in parallel, large amounts of energy can be passed through a laser, but with better control such that the aforementioned problems can be reduced. An additional advantage is that the polarization of the light can be maintained better than by using a single fiber core.

Abstract: The present invention provides a multi-stage optical amplifier including a high SN ratio and a method of controlling the same. A multi-stage optical amplifier is configured such that the gain of an amplifying unit in a first stage is greater than that of an amplifying unit in another stage. Therefore, it is possible to increase signal components that have been reduced due to spontaneously emitted light in the first stage, and thus relatively reduce noise. As a result, the obtained signals including a high SN ratio can be maintained in another stage, and it is possible to obtain a high SN ratio.

Abstract: A phosphate glass 1-?m fiber ASE source provides high power and broadband emission that covers wavelengths on the short side of Yb-doped silica. A single-mode fiber formed from phosphate glass is doped with highly elevated concentrations of Yb dopants 0.5-30 wt. % and typically 2-10 wt. %, far higher than either silica or germano-silicate. The high concentration of Yb dopant absorbs the pump in a short length, typically 10-150 cm instead of tens of meters, to provide high saturated output power and a shifted emission spectrum. The excess power allows the fiber ASE source to be configured to provide the output powers, emission bandwidth and stability desired by many applications. Furthermore, the ASE can be configured to emit a nearly Gaussian spectral profile without sacrificing power or bandwidth.

Abstract: A cascaded optical amplifier including a first optical amplifier and a second optical amplifier in cascaded arrangement is provided. Each of the first optical amplifier and the second optical amplifier has a respective input for receiving an optical signal, an output for outputting an amplified optical signal, and a control input for controlling the gain of the optical amplifier. The cascaded optical amplifier includes a sensor for sensing upstream of the input of the second optical amplier a signal relating to operation of the cascaded optical amplifier. In addition, the cascaded optical amplifier includes a controller for providing control signals to the respective control inputs of the first amplifier and the second amplifier, the controller providing the control signal to the second optical amplifier as a function of the sensed signal.