Abstract: The alteration of the bandwidth of an optical amplifier. Before alteration, optical signals having a first set of wavelengths are provided through a gain medium of the optical amplifier. In addition, a first pump having a set of pump wavelengths is propagated through the gain medium to thereby amplify the optical signals. After alteration, optical signals having at least a partially different set of wavelengths are able to be optically amplified by coupling a second pump into the optical medium. The second pump is at least partially distinct from the first pump in that the second pump includes at least one pump wavelength that was not included in the first pump.

Abstract: Embodiments of optical fiber may include cladding features that include a material (e.g., fluorine-doped silica glass) that may produce a very low relative refractive index difference with respect to cladding material in which the cladding features are disposed. This relative refractive index difference may be characterized by (n1?n2)/n1, where n1 is the index of refraction of the cladding material in which the cladding features are included, and n2 is the index of refraction of the cladding features. In certain embodiments, the relative refractive index difference may be less than about 4.5×10?3. In various embodiments, the configuration of the cladding features including, for example, the size and spacing of the cladding features, can be selected to provide for confinement of the fundamental mode yet leakage for the second mode and higher modes, which may provide mode filtering, single mode propagation, and/or low bend loss.

Abstract: An optical modulator combines and inputs a signal light propagating through the optical network and a control light having information concerning the optical network to a nonlinear optical medium. The optical modulator modulates the signal light according to changes in intensity of the control light, in the nonlinear optical medium.

Abstract: An optical amplification mechanism that introduces optical pump(s) into one port of an optical circulator. The optical circulator directs the optical pumps from that port into another port that is coupled to the output of a gain stage. The optical pump(s) then pass from the output to the input of the gain stage while amplifying an optical signal passing from the input to the output of the gain stage. A residual amount of optical pump(s) that exits the input of the gain stage is reflected back into the input of the gain stage. The reflected optical pump(s) then further assists in the amplification of the optical signal. Other embodiments are also disclosed.

Abstract: An optical amplifier with improved transient performance has two amplifier stages and a gain flattening filter-inserted between the amplifier stages. A control unit generates a pump control signal for a common pump source pumping both amplifier stages. The pump control signal has a feed-forward component and a feedback component. After a drop of channels the feed-forward control circuit is responsible for the transient performance and fast gain stabilization. The characteristic of the gain flattening filter is taken into account in calculating an optimum feed-forward control signal.

Abstract: An optical amplifier with improved transient performance has two amplifier stages and a dispersion compensating fiber inserted between the amplifier stages. A control unit generates a pump control signal for a common pump source pumping both amplifier stages via a power splitter. The pump control signal has a feedforward component with a delayed reaction. A feedforward delay time is adjusted to minimize gain variations resulting from input power drops. In a preferred embodiment, the splitting ratio of the power splitter is adjustable to achieve, for instance, either optimum steady-state performance or optimum transient performance.

Abstract: The invention relates to an apparatus for coupling light into an optical wave guide, a laser system with such an apparatus, and a preform to manufacture the apparatus for coupling light into an optical wave guide with the aid of a pumping fiber to guide the light, whereby the optical wave guide comprises a core with a cladding and an initial length segment with a second length segment immediately connected to it, whose cross section increases in tapered form with respect to the first length segment.

Abstract: It is disclosed a method for driving a laser diode such as to enable mitigation or elimination of so called spiking effects related to the number of injected carriers in the laser overshooting the equilibrium value at the beginning of the lasing process. In this manner, among other things, the efficiency of a master oscillator power amplifier that may be utilized in range finding applications will be improved. It is further disclosed an optical pulse transmitter comprising such a laser diode.

Abstract: The present invention has an object to provide an optical amplifier capable of realizing a good response characteristic in a wide frequency band, even when a population inversion state is formed by a pumping light supplied to an optical amplification medium and an ASE light generated in the optical amplification medium. To this end, in the optical amplifier according to the present invention, a delayed phase matching fiber in which a first fiber whose response speed is relatively low is arranged on the input side and a second fiber whose response speed is relatively high is arranged on the output side, is used as the optical amplification medium doped with a rare-earth element.

Abstract: An optical fiber includes a central core for transmitting and amplifying an optical signal, an optical cladding to confine the optical signal transmitted by the central core, and an outer cladding. The central core is formed of a core matrix and nanoparticles. The nanoparticles are formed of a nanoparticle matrix and rare earth dopants (i.e., a nanoparticle matrix surrounding the rare earth dopants). The optical cladding has a plurality of holes separated by a pitch and extending along the length of the optical fiber.

Abstract: Fiber amplifiers and oscillators include tapered waveguides such as optical fibers that permit multimode propagation but produce amplification and oscillation in a fundamental mode. The tapered waveguides generally are provided with an active dopant such as a rare earth element that is pumped with an optical pump source such as one or more semiconductor lasers. The active waveguide taper is selected to taper from a single or few mode section to a multimode section, and seed beam in a fundamental mode is provided to a section of the waveguide taper associated with a smaller optical mode, and an amplified beam exits the waveguide taper at a section associated with a larger optical mode.

Abstract: In various embodiments, an optical element, e.g., an optical fiber, may be configured to compensate for thermal lensing. For example, thermal lensing may be caused by light power dissipation within an optical fiber, which may include a fiber core that guides amplified light along the longitudinal dimension of the fiber core. Thermal lensing from a thermally induced change in material refractive index as a function of position along dimensions perpendicular to the fiber's longitudinal dimension may be at least partially compensated or offset when light is guided by the fiber core by a designed-in effective refractive index profile selected such that the designed-in material refractive index of the fiber core changes as a function of transverse position within the fiber core, or by selection of a favorable cross-sectional core shape in a plane perpendicular to the longitudinal dimension of the fiber core.

Abstract: The invention provides an amplification optical fiber, which can output light with a good beam quality even when a higher-order mode is excited, and an optical fiber amplifier using the amplification optical fiber. An amplification optical fiber 50 has a core 51 and a clad 52 covering the core 51. The core 51 propagates light with a predetermined wavelength in at least an LP01 mode, and an LP02 mode, and an LP03 mode. When the LP01 mode, the LP02 mode, and the LP03 mode are standardized by power, in at least a part of a region where the intensity of the LP01 mode is larger than at least one of the intensities of the LP02 mode and the LP03 mode, the active element is added to the core 51 at a higher concentration than the central portion of the core.

Abstract: An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

Abstract: An optical fiber apparatus is suitable to operate under irradiation, more particularly to mitigating the damage of a rare-earth-doped optical fiber element as part of an optical fiber assembly causes by irradiation. The irradiation mitigation attributes to a photo-annealing apparatus including at least a shorter wavelength photo-annealing spectral content, which is relative to that of a pump light source, for effectively photo-annealing the rare-earth-doped fiber element. Photo-annealing by such shorter wavelength light results in a fast and nearly complete recovery of radiation induced attenuation of the rare-earth-doped optical fiber element in the wavelength range from 900 nm to 1700 nm.

Abstract: A tapered fiber bundle device couples optical power from an optical power source into an output fiber. The tapered fiber bundle device includes a tapered fiber bundle including a set of bundled fibers having a near end and a distal end. The near end of the tapered fiber bundle is configured to collect the optical power from the optical power source. Each fiber k in the set of bundled fibers has a first cross-sectional area Ak(1) at the near end and a second cross-sectional area Ak(2) at the distal end such that Ak(2) is substantially smaller than Ak(1). Each fiber also has a substantially uniform core and a substantially uniform numerical aperture value NAin. A cross-sectional area of the set of bundled fibers at the distal end has a cross-sectional area value Adist substantially equal to Aout.

Abstract: The invention provides an amplification module for an optical printed circuit board, the optical printed circuit board comprising plural polymer waveguide sections from independent waveguides, each of the sections being doped with an amplifying dopant, wherein the plural waveguide sections are routed so as to pass through an amplification zone in which the plural polymer waveguide sections are arranged close or adjacent to one another, the amplification module comprising: a pump source comprising plural light sources arranged to provide independently controllable levels of pump radiation to each of the plural waveguide sections. In an embodiment, the amplification module also includes plural polymer waveguide sections corresponding to the plural polymer waveguides of the printed circuit board on which in use the amplification module is to be arranged, each of the sections being doped with an amplifying dopant.

Abstract: A generation unit generates a polarization multiplexing signal in which two optical signals, each polarization of which is orthogonal to each other, are combined. A detector detects the powers of the two optical signals contained in the polarization multiplexing signal generated by the generation unit. An amplifier amplifies, according to each polarization of the two optical signals contained in the polarization multiplexing signal generated by the generation unit, the powers of the two optical signals. An controller controls a gain of the amplifier with respect to each polarization of the two optical signals so as to reduce difference in the powers of the two optical signals detected by the detector.

Abstract: A rare-earth doped optical fiber that includes a core and one or more clad layers surrounding the core, in which the core has a rare earth dopant, and a relationship of Equation (1) is satisfied: 0 < ? r 0 r c ? D ? ( r ) · P p 2 ? ( r ) · P s 2 ? ( r ) ? r ? ? ? r ? r 0 r c ? D ? ( r ) · P p 2 ? ( r ) ? r ? ? ? r ? 0.35 ( 1 ) where Pp(r) represents an electric field distribution in an exciting wavelength, Ps(r) represents an electric field distribution in wavelengths of spontaneous emission and/or stimulated emission carried in the core, D(r) (mass %) represents a rare-earth dopant distribution, ro represents a core center, and rc represents a core radius.

Abstract: Method and apparatus for detecting an opening in a transmission fiber connecting a discrete gain unit to a pump unit of a Remote Optically Pumped Amplifier (ROPA) system. The method comprises measuring an optical power entering the pump unit from the transmission fiber, the optical power being in a selected wavelength range, and establishing that the optical power lacks an ASE noise power component generated by the gain unit. The lack of this component indicates the presence of a break or opening in the transmission fiber, and triggers corrective action whereby pump lasers within the pump unit are shut down or have their power reduced to a safe level.

Abstract: An optical apparatus (100), an optical system (200) and a method (300) of light amplification by stimulated emission employ an endohedral metallofullerene (120, 220) as an active material coupled to an optical waveguide (110, 210). The endohedral metallofullerene (120, 220) is optically coupled to an optical field of the optical waveguide (110, 210). The coupled optical field produces a stimulated emission in the endohedral metallofullerene (120, 220). The optical system (200) further includes an optical source (230) that generates optical power (232) to pump a stimulated emission. The method (300) further includes optically pumping (330) the coupled endohedral metallofullerene by introducing an optical pump into the optical waveguide.

Abstract: Cross-distribution of the output pump power from optical pump units amongst multiple amplifier gain stages even in a single direction of an optical link in an optical communications system. For example, an optical pump unit may output optical pump power that is shared amongst a discrete optical amplification unit and a distributed optical amplification unit (such as a forward and/or backward Raman amplifier). Such sharing has the potential to increase reliability and/or efficiency of the optical communications system.

Abstract: A light output control apparatus, includes: an excitation light source that outputs excitation light; an excitation light guiding unit that guides the excitation light to an optical amplifying medium for transmitting a signal light; and a loss causing unit that includes an optical transmission medium located between the excitation light source and the excitation light guiding unit, and changes a radius of curvature of the optical transmission medium.

Abstract: A light amplifier includes a single crystal semiconductor substrate with a rare earth oxide, light amplifying gain medium deposited on the substrate and formed into a light waveguide, and a pump laser. A lattice matching virtual substrate integrates the pump laser to the gain medium with a first opposed surface crystal lattice matched to the gain medium and second opposed surface crystal lattice matched to the pump laser. The pump laser is positioned with a light output surface coupled to a light input surface of the gain medium so as to introduce pump energy into the light waveguide. The light amplifier has a very small footprint and allows the integration of control and monitoring electronics.

Abstract: The present invention discloses a fiber amplifier, a fabricating method thereof, and a fiber communication system. The fiber amplifier includes at least a pump laser, at least a gain medium and at least an integrated optical component. The integrated optical component includes multiple optical input/output ports, and the optical input/output ports are connected to the pump laser or gain medium directly or indirectly. The present invention may better address problems of unstable performance and difficulty in reducing the size of components in the prior art where fiber amplifiers are formed by a number of discrete components with many fiber fusion splices. In addition, the present invention may reduce the production complexity and costs of fiber amplifiers, and improve the productivity of fiber amplifiers.

Abstract: The invention relates to a multistage fiber amplifier having a first amplifying fiber, at least one further amplifying fiber connected in series with the first amplifying fiber, a pump source, a first pump signal fed to the first amplifying fiber, and a further pump signal fed to the further amplifying fiber. The multistage fiber amplifier is distinguished by the fact that a further pump signal is fed to a further amplifying fiber via a power-dependent attenuation element. The attenuation element is formed in such a way that, as the pump power increases, small further pump signals are attenuated to a greater extent than large further pump signals. The power-dependent attenuation of the further pump signal that is fed to the further amplifying fiber and therefore the increased pump signal that is fed to the first amplifying fiber result in improvements in the noise figure of the multistage amplifier.

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: A fiber laser apparatus includes an optical amplification fiber with a multi-core structure composed of a first waveguide that pumping light enters and that transmits the pumping light; a second waveguide composed of a core containing a laser medium and for generating laser, and a clad for transmitting pumping light; and a third waveguide containing the first waveguide and the second waveguide. The optical amplification fiber is wound while the curvature radius is being changed to provide a small-size, high-power fiber laser apparatus.

Abstract: A master oscillator power-amplifier stages includes multiple stages of fiber-amplification with a final power amplifier stage in the form of a multi-pass amplifier. With a thin-disk gain medium in one example the thin-disk amplifier includes a common optical arrangement for providing multiple incidences of radiation to be amplified and multiple incidences of a pump-radiation beam on the thin-disk gain medium.

Abstract: The invention relates to a light source apparatus having a structure for effectively suppressing a negative effect due to a nonlinear effect generated in propagation of an amplifying light, and realizing a stable operation. In the light source apparatus, light amplified in an optical amplifier fiber is emitted to the outside of the apparatus through an optical output fiber whose one end is connected to an output connecter. At this time, a part of Raman scattered light, generated in the optical output fiber, propagates toward an pumping light source through the optical amplifier fiber from the optical output fiber. An optical component having an insertion loss spectrum that attenuates the Raman scattered light but allows pumping light or light to be amplified to transmit therethrough, is provided on a propagation path of the Raman scattered light, due to the light component, the intensity of the Roman scattered light reaching the pumping light source is effectively reduced.

Abstract: A twin fiber laser arrangement is configured with active and passive fibers supporting respective signal and pump lights and a reflective coating surrounding the fibers along a section of the arrangement. The passive fiber has regions covered by respective protective layer and coating-free regions alternating with the layer covered regions, wherein the reflective coating is configured to overlap the protective layer which shields the end of the reflective coating from high power pump light.

Abstract: An optical amplifier includes an optical fiber which includes a core in which the signal light is propagated and with which a rare-earth element is doped; a laser that is optically coupled to an end of the optical fiber, providing the optical fiber with an excitation light; and a filter which is formed in the optical fiber and removes a light within a wavelength range, from the core, among lights propagated in the core, wherein the filter comprises a first filter that is arranged at a stage of the optical fiber and removes a first light in a first wavelength range, and a second filter that is arranged at a subsequent stage of the optical fiber and removes a second light in a second wavelength range, wherein a wavelength of the second light is longer than a wavelength of the first light.

Abstract: A new broadband source having a discrete set of spectral emission lines having high peak power in each line is provided by placing a gain medium in a reflective cavity comprising reflective front and back surfaces. A cavity feedback factor less than unity is achieved by providing reflectivity of one surface substantially lower than the reflectivity of the other surface such that spontaneous emission in the gain medium is linearly amplified just below the lasing threshold. In an alternative arrangement, a movable external back surface placed at a prescribed distance from the gain medium provides a means to achieve a free spectral range and finesse of the emission lines to match a pitch of a detector array in a SD-OCT system. By simultaneously providing high power to each detector element of the array, sensitivity and imaging speed of SD-OCT system are significantly improved.

Abstract: An object of the present invention is to provide an optical fiber amplifier capable of suppressing oscillation of ASE. The optical fiber amplifier includes a second amplifier fiber 30 doped with a rare earth element; a second pumping source 26 that supplies pump light to the second amplifier fiber 30; a storage unit 40 for storing a relationship between oscillation threshold pump power and temperature of the second amplifier fiber 30, the oscillation threshold pump power being power of the pump light which causes oscillation of ASE in a different wavelength range from a signal wavelength range produced by the second amplifier fiber 30; and a temperature controller 38 for controlling the temperature of the second amplifier fiber 30 so that the oscillation threshold pump power is higher than the power of the pump light outputted by the second pumping source 26, by referring to the relationship stored in the storage unit 40.

Abstract: The invention relates to a method and a device for illuminating or irradiating an object, a sample (8), or the like, for the purpose of imaging or analysis, particularly for use in a laser microscope (1), preferably in a confocal microscope having a laser light source (2) emitting the illuminating light, the laser light being coupled directly or by means of a glass fiber into an illumination light path (4), characterized in that the laser light source (2) is switched on rapidly upon a trigger signal directly prior to the actual need, for example, directly prior to imaging.

Abstract: An optical transmission and amplification system includes a multichannel transmission span with a length of a multicore transmission fiber having a plurality of individual transmission cores. A first tapered multicore coupler provides connectivity between the plurality of transmission cores of the multicore fiber and a respective plurality of individual transmission leads. A fiber amplifier is provided having a plurality of individual cores including at least one pump core and a plurality of amplifier core. A second tapered multicore coupler provides connectivity between the amplifier cores of the fiber amplifier and a respective plurality of amplifier leads, and between the at least one pump core and a respective pump lead.

Abstract: A device for amplifying optical signals propagating in optical fibers comprising a double cladding fiber amplifier having multiple gain stages, a port for coupling pump light into the double cladding fiber amplifier, and a double cladding fiber coupler for splitting the coupled pump light between the gain stages of the double cladding fiber amplifier. Also, a method for amplifying optical signals propagating in optical fibers comprising the steps of providing a double cladding fiber amplifier having multiple gain stages, coupling pump light into the double cladding fiber amplifier, and splitting the coupled pump light between the gain stages of the double cladding fiber amplifier.

Abstract: The present invention relates to a light source apparatus that has a base structure capable of generating SC light and further having a structure that enables the shaping of the spectral waveform of the SC light, power adjustment of the SC light, or adjustment of the frequency of repetition of the pulse train that contains the SC light. For example, a light source apparatus that enables shaping of spectral waveforms comprises a seed light source that emits seed light which is a pulse train or continuous light; an optical fiber that generates SC light from the seed light, and spectrum shaping means for completely or partially changing the spectral waveform of the SC light. The shaping of the spectral waveform changes the maximum power of the seed light by changing the optical coupling efficiency of the seed light source and optical fiber, for example, thereby suitably deforms the spectrum of the SC light.

Abstract: Systems and methods for modulating the output of a difference frequency generator such as an OPO, OPA or OPG include a pump fiber laser having at least one internal, directly modulatible component, wherein the pump fiber laser produces a pump signal, and a difference frequency generator coupled to the pump fiber laser. The difference frequency generator is configured for accepting the pump signal of the pump fiber laser and producing an output signal, wherein parameters of the output signal are determined based on direct modulation of the internal, directly modulatible component of the pump fiber laser.

Abstract: An optical signal processing apparatus includes an input unit to which signal light is input; a wave coupling unit that couples the signal light from the input unit and pump light having a waveform different from that of the signal light; a first nonlinear optical medium that transmits light coupled by the wave coupling unit, the light being the signal light and the pump light; a dispersion medium that transmits the light that has been transmitted through the first nonlinear optical medium; and a second nonlinear optical medium that transmits the light that has been transmitted through the dispersion medium.

Abstract: An optical signal processing device has nonlinear optical medium, first and second power controllers, and polarization controllers. To the nonlinear optical medium, signal light, and first and second pumping lights having wavelengths different from the signal light are input. The first and the second power controllers are provided at the input side of the nonlinear optical medium, and control the powers of the first and the second pumping lights so that a predetermined gain is obtained in the nonlinear optical medium. The polarization controllers are provided at the input side of the nonlinear optical medium, and adjust the first and the second pumping lights so that the polarization states of the first and the second pumping lights are mutually orthogonal.

Abstract: A method and apparatus for mode-matching double-clad fibers. In some embodiments, a first fiber section that has a first core, wherein the first core has a first core diameter connects to a mode-field adaptor, wherein the mode-field adaptor includes a first portion having a central volume that has a substantially constant index-of-refraction radial profile and a diameter larger than the first core diameter, and a second portion that has a graded-index (GRIN) central volume, wherein the GRIN central volume has a central axis and a graded index-of-refraction radial profile having an index that gradually decreases at larger distances from its central axis and a length selected to focus light into the core of a second fiber wherein the second core has a diameter that is larger than the first core diameter, and wherein the second fiber section is double clad. Some embodiments are polarized.

Abstract: In some embodiments, the present invention provides an apparatus, method and use for improving and merging two existing techniques (core pumping and cladding pumping) to enable high-power fiber-laser systems having excellent beam quality while using large-core (LMA) step-index gain fibers at very high optical power, wherein the core pumping includes mixing a laser seed optical signal (having a signal wavelength) with optical core-pump light (having a core-pump wavelength that is near the signal wavelength) in a manner that matches the modes of the seed optical signal and the pump light. The combined core light is mode matched to the LMA gain fiber. The core-pump light is substantially all absorbed within a short distance from the entry end of the gain fiber and provides a strong pre-amplified signal for later cladding-pumped amplification. In some embodiments, the signal wavelength and the core-pump wavelength are within a single multiplet of a rare-earth dopant.

Abstract: The optical transmission system modulates backward Raman pump light provided to an optical transmission line on one link side of an uplink and downlink, to thereby transmit a pilot signal for confirming a connection state of the optical transmission line to a node on an upstream side. When the pilot signal is received by the node on the upstream side, the backward Raman pump light provided to the optical transmission link on the opposite link side is modulated to thereby send back a response signal to an own node. Then by confirming receipt of the response signal at the own node, the backward Raman pump light provided to the optical transmission line on the one link side is changed over from a low output state to a high output state.

Abstract: An amplification optical fiber with an optical component capable of efficiently absorbing pumping light and a fiber laser device including the same are provided. An amplification optical fiber with an optical component in a fiber laser device 1 includes: an amplification optical fiber 30 having a core 31 doped with an active element and a clad 32 through which pumping light for amplifying light to be amplified propagating through the core 31 propagates; and an optical component 50 including at least one optical fiber 53a to 53f having a first end coupled to a portion of the clad 32 and a second end coupled to at least another portion of the clad 32 at one end 35 of the amplification optical fiber 30.

Abstract: A first optical fiber (12) having a first end and a second end is connected to a multimode second optical fiber (14) at the second end. The first optical fiber (12) outputs a substantially single mode optical beam at its second end. The multimode second optical fiber (14) converts light in the optical beam of single mode from the first optical fiber to light of multiple modes, and provides an output beam that has less diffractive spreading than that of a Gaussian beam.

Abstract: A Raman amplifier provided with a pump source outputting a pumping light; a rare-earth doped fiber inputting the pumping light and outputting an excitation light; and a guiding unit guiding the excitation light to an optical fiber to a direction opposite to which a signal light propagates in the optical fiber. Also a Raman amplifier provided with a plurality of pump sources outputting a plurality of pumping lights; a plurality of rare-earth doped fibers inputting the each of the plurality of pumping lights and outputting a plurality of excitation lights; a guiding unit guiding the plurality of excitation lights to an optical fiber to a direction opposite to which a signal light propagates in the optical fiber.

Abstract: The invention relates to a high power amplifier waveguide for amplifying an optical signal wherein photo darkening due to high optical flux is reduced considerably. This is achieved by providing a cladding pumped amplifier waveguide wherein the optical mode overlap to the active material of the waveguide is low and/or wherein the active material is distributed over a large cross sectional region of the waveguide.

Abstract: The fiber laser apparatus comprises an amplifying section for amplifying seed light by cladding-pumping, and has a structure for further using a residual component of pumping light for cladding-pumping in order to heat the object. A guiding optical fiber is provided between an amplifying optical fiber of the amplifying section and an output optical system converging the single-mode amplified seed light on the object, the guiding optical fiber serving to increase the degree of freedom in arranging the output optical system. The guiding optical fiber has a structure enabling the single-mode propagation of the amplified seed light outputted from the amplifying optical fiber and multimode propagation of the residual pumping light. Because the object is irradiated with the converged amplified seed light, while being heated with the residual pumping light outputted from the output optical system, even an object with a complex shape can be subjected to efficient laser processing.

Abstract: An optical amplifier for pulsed laser with short or ultra-short and energetic pulses includes an optical pumping source for generating a pump wave, an elongate amplifying medium including an input interface for receiving an optical signal to be amplified, the medium being able to amplify the optical signal propagating along the amplifying medium and to extract an amplified signal and an optical system for coupling the pump wave in the amplifying medium so as to pump the amplifying medium longitudinally. The amplifying medium has a minimum transverse dimension ?3 and the optical system focuses the pump wave inside the gain medium, the focused pump wave having a transverse dimension ?6 which is smaller than the dimension ?3 of the medium and a smaller numerical aperture than the numerical aperture of the medium, so that the pump wave propagates freely over a part of the amplifying medium and then in a confined manner over a part of the amplifying medium.