Abstract: It is desirable to provide a semiconductor optical amplifier from which it becomes able to obtain a higher output power. A semiconductor optical amplifier in comprises an active wave guiding layer which comprises a passive core region that is formed of a semiconductor, and active cladding regions that are located at both sides of the passive core region and each of that is comprised of an active layer which is formed of a semiconductor and which has an index of refraction to be lower than that of the passive core region, wherein a light is wave guided with being amplified in the active wave guiding layer. Moreover, it is desirable for the active wave guiding layer to be formed of a compound semiconductor, and to be formed by integrating the passive core region and the active cladding regions to be monolithic on to a substrate that is formed of a compound semiconductor by making use of a process of a butt joint growth.

Abstract: A semiconductor optical amplifier includes a semiconductor substrate; an optical waveguide that includes an active layer formed on the semiconductor substrate; and a wavelength selective reflection film that is formed on an end face where signal light is incident on the optical waveguide the wavelength selective reflection film allows transmission of the signal light, and reflects light of any wavelength other than the signal light.

Abstract: An optical signal amplifying apparatus feeding back surrounding light to perform negative feedback optical amplification of a semiconductor optical amplifier is provided that enables a coupling structure to be simplified and miniaturized between the semiconductor optical amplifier and an optical fiber transmitting the output light from the semiconductor optical amplifier by using a fiber grating device.

Abstract: A method is provided for forming an optical fiber amplifier. The method comprises providing a composite preform having a gain material core that includes one or more acoustic velocity varying dopants to provide a longitudinally varying acoustic velocity profile along the gain material core to suppress Stimulated Brillouin Scattering (SBS) effects by raising the SBS threshold and drawing the composite preform to form the optical fiber amplifier.

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: Apparatus and method for amplifying laser signals using segments of fibers of differing core diameters and/or differing cladding diameters to suppress amplified spontaneous emission and non-linear effects such as four-wave mixing (FWM), self-phase modulation, and stimulated Brillouin and/or Raman scattering (SBS/SRS). In some embodiments, different core sizes have different sideband spacings (spacing between the desired signal and wavelength-shifted lobes). Changing core sizes and providing phase mismatches prevent buildup of non-linear effects. Some embodiments further include a bandpass filter to remove signal other than the desired signal wavelength and/or a time gate to remove signal at times other than during the desired signal pulse. Some embodiments include photonic-crystal structures to define the core for the signal and/or the inner cladding for the pump.

Abstract: [Object] An optical amplifier and a resonator capable of outputting output light having a high intensity are provided.

Abstract: A telecommunications system and constituent two-wire interface module. The two wire interface module includes a logic component configured to communicate over the same pair of wires using different two-wire interface protocols depending on an input signal presented on a configuration input. This configurability allows the two-wire interface module to use the same two wires to communicate with a variety of other two-wire interface modules, even if those two-wire interface modules communicate using different two-wire interface protocols.

Abstract: An optical amplifier with optical gain-control (OGC) has an input (11) for the signals to be amplified and an output (12) for the amplified signals. It comprises in series a first Bragg grating (BG) (15), a variable optical attenuator (VOA) (17), an optical amplification unit with pump (13) and a second Bragg grating (BG) (14). The two gratings define between them a laser cavity with the amplification unit (13) in the middle and the signals to be amplified are placed at the input of the amplification unit (13) with a splitter (16) at the input of the amplification unit. A network with nodes comprising said amplifiers is also described.

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: An amplifying optical electromagnetic wave concentrator includes an amplification focusing device and a receiver. The amplification focusing device focuses an incident optical electromagnetic wave on the receiver. The amplification focusing device is doped with active components and is subjected to an excitation wave that causes the active components to pass to an energy level such that interaction between the incident electromagnetic wave and the active components causes the active components to pass to a lower energy level and causes emission, towards the receiver, of at least one photon having the same wavelength as the incident electromagnetic wave. The focused photon or photons form an amplified wave of the incident electromagnetic wave.

Abstract: Systems and methods are disclosed for amplifying optical signals in the 850 nm window. In one embodiment, an amplifier system includes a span of Thulium-doped fiber (TDF) and two pump systems. The TDF span receives and transports optical signals in the 850 nm window. A first pump system pumps the TDF span at a wavelength in the range of 1390 nm to 1430 nm, and a second pump system pumps the TDF span at a wavelength in the range of 670 nm to 720 nm. The pumping generates gain in the optical signals in the 850 nm window. In another embodiment, the amplifier system includes a single pump system. The pump system pumps the TDF span at a wavelength in the range of 1390 nm to 1430 nm to generate gain in the 850 nm window.

Abstract: A high power integrated fiber laser system includes cascaded amplifiers that utilize low numerical aperture fiber amplifiers. The system is rugged and lightweight.

Abstract: Disclosed is an optical fiber that includes a central core that is suitable for transmitting and amplifying an optical signal and an inner optical cladding that is suitable for confining the optical signal transmitted within the central core. The central core is formed from a core matrix that contains silica-based nanoparticles doped with at least one rare earth element. The disclosed optical fiber can be used with limited optical losses even in an environment with strong ionizing radiation.

Abstract: Disclosed is an amplifying optical fiber that includes a central core that is suitable for transmitting and amplifying an optical signal and a surrounding optical cladding that is suitable for confining the optical signal transmitted in the central core. The central core is formed from a main matrix that contains nanoparticles doped with at least one rare earth element. The weight concentration of the rare earth dopants in the nanoparticles is typically between about 1 and 20 percent, and the nanoparticle concentration in the central core's main matrix is between about 0.05 percent and 1 percent by volume. The disclosed optical fiber incorporates rare earth ions at high concentrations yet avoids the phenomenon of photodarkening at high transmission power.

Abstract: An optical fiber includes: a first core portion doped with rare earth ions; a second core portion having a lower refractive index than that of the first core portion, provided along an outer circumference of the first core portion, and doped with the rare earth ions; and a clad portion having a lower refractive index than that of the second core portion and provided along an outer circumference of the second core portion, and is configured such that a concentration of the rare earth ions added to the second core portion is higher than that to the first core portion. With this configuration, it is possible to suppress an amount of FWM crosstalk in an optical amplification by decreasing the length of a fiber while alleviating efficiency deterioration due to concentration quenching.

Abstract: Optical apparatus (110, 500, 600, 800, 1000) for providing light having a selected linear polarization having a polarization ratio, the apparatus (110, 500, 600, 800, 1000) comprising a length of optical fiber (120, 504, 604, 804, 1001) comprising a rare earth for providing light having a first wavelength responsive to receiving pump light having a second wavelength that is different than said first wavelength, wherein if the length of optical fiber (120, 504, 604, 804, 1004) were placed in a first position between the length of fiber (120, 504, 604, 804, 1004) is substantially linearly oriented (20) the fiber (120, 504, 604, 804, 1004) could propagate at the first wavelength a fundamental mode and a plurality of higher order modes and the apparatus (110, 500, 600, 800, 1000) could provide light having a first polarization ratio for the selected linear polarization and an M2 parameter, and wherein the length of fiber (120, 504, 604, 804, 1004) is positioned in a second position that increases the bend loss of

Abstract: A laser-system comprises master-oscillator/power-amplifier (51) whereby the master-oscillator comprises a pulsed diode (3) and a pumped active optical fiber power-amplifier (9). Substantially all guides of laser light (5, 9, 31, 29, 33, 25, 35, 39, 45) are optical fibers. The pulsed diode (3) is not temperature stabilized. To reduce nevertheless amplified spontaneous emission generated in the optical fiber amplifier (9), a narrow band-pass filter unit (29) is used. Filter unit (29) has a central wavelength with a temperature dependence which is matched to the temperature dependent wavelength shift of the pulsed diode (3).

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: An optical fiber comprising a core region embedded within a cladding. The core region of the optical fiber further comprises multiple sections, each doped with rare earth ions. The sections of the core region may be doped with different rare-earth ions or with different doping concentrations. The sections of the core region may also be made from different types of glass hosts. The optical fiber may further include multiple core regions embedded within the cladding, each core region having multiple sections doped with rare earth ions.

Abstract: The present invention relates to an optical module which is capable of amplifying light to be amplified to high power and which has a structure for effectively reducing influences of damage to other optical parts, and heat generation. The optical module includes a fiber unit constituted by an optical coupler, an amplification optical fiber, and an absorption optical fiber. Each of the amplification optical fiber and the absorption optical fiber has a core, a first cladding, a second cladding, and a third cladding. Further, each of the fibers allows the light to be amplified to propagate in a single mode in each of the cores, and allows pumping light to propagate in a multimode in the core, the first cladding, and the second cladding. The core of the amplification optical fiber is doped with an amplification dopant for amplifying the light to be amplified. The second cladding of the absorption optical fiber is doped with an absorption dopant for absorbing the pumping light.

Abstract: A MO-PA type optical amplifier is provided which includes an oscillator and an amplifier including a fiber for optical amplification, including: a reflected-light wavelength conversion fiber which is provided on an optical path between the oscillator and the amplifier and which converts a wavelength of reflected-light traveling toward the oscillator due to Stimulated Raman Scattering; and a filter which is provided on the optical path between the oscillator and the amplifier and which eliminates the wavelength-converted light.

Abstract: A parametric process is provided for producing visible light at a second wavelength including pumping an optical fiber (4) with input light (1) at a first wavelength of less than one micron, which is longer than the second wavelength, and wherein the optical fiber (4) has zero group velocity dispersion at a third wavelength in the visible or near infrared region and longer than the first wavelength. An optical amplifier that uses the parametric process for producing light at second wavelength is also provided. The optical fiber (4) may be a photonic crystal fiber. The parametric process is tuneable by adjusting the frequency of the zero group velocity dispersion, the frequency of the first wavelength or the birefringence of the optical fiber (4).

Abstract: A narrow-linewidth micropulse LIDAR transmitter based on a low-SBS single clad, small-mode-area optical fiber. High narrow-linewidth peak powers are achieved through the use of an erbium doped fiber with an acoustic waveguide. Over 6 ?J per pulse (100 ns pulse width) is achieved before a weak form of stimulated Brillouin scattering appears. This laser has the potential to scale to very high power in a low-SBS dual clad fiber.

Abstract: A rare-earth doped core multi-clad fiber includes a core that includes a rare-earth element and a plurality of cladding layers that surround the core. An outermost cladding of the plurality of cladding layers is made of a polymer cladding, the plurality of cladding layers have a polygonal inner cladding, and a shape of a boundary between a second cladding from the outside and the outermost cladding does not have two-fold rotational symmetry. As a result, it is possible to provide a rare-earth doped core multi-clad fiber for an optical amplifier and a fiber laser that has low skew and is inexpensive.

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 laser oscillator includes a ring resonator. The ring resonator includes an optical circulator having first, second, third, and fourth ports and a first optical amplification fiber connected to the optical circulator. Light incident on the first port is exited from the second port, and light incident on the second port is exited from the third port. The fourth port provides an exciting light and injects the exciting light into the ring resonator through the first port. The first optical amplification fiber amplifies light exited from the third port with the exciting light provided by the fourth port. The laser oscillator also includes an optical member connected to the optical circulator. The optical member reflects at least a part of the light exited from the second port and injects the same into the second port again.

Abstract: An electronic circuit for controlling a laser system consisting of a pulse source and high power fiber amplifier is disclosed. The circuit is used to control the gain of the high power fiber amplifier system so that the amplified output pulses have predetermined pulse energy as the pulse width and repetition rate of the oscillator are varied. This includes keeping the pulse energy constant when the pulse train is turned on. The circuitry is also used to control the temperature of the high power fiber amplifier pump diode such that the wavelength of the pump diode is held at the optimum absorption wavelength of the fiber amplifier as the diode current is varied. The circuitry also provides a means of protecting the high power fiber amplifier from damage due to a loss of signal from the pulse source or from a pulse-source signal of insufficient injection energy.

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: An optical fiber arrangement has at least two optical fiber sections, each optical fiber section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fiber arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fiber. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fiber and a first multiplexer connected to the input fiber. Each amplifier is configured such that at least one of the amplifying optical fibers is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: Provided is a fiber ring laser capable of obtaining a back-up laser light and standard light having a wavelength continuously tuned in a single mode with equal spacing of 12.5 GHz, 25 GHz, 50 GHz or 100 GHz recommended by ITU-T Recommendation G. 692 & G. 694.1 in a C-band and an L-band using a fiber tunable etalon filter, an air gap etalon filter and a saturable absorber in an optical fiber laser resonator having a serial ring shape using a C-band optical amplifier and an L-band optical amplifier. The fiber ring laser can generate laser light having a wavelength tuned by more than 70 nm, excellent output power flatness and a source spontaneous emission ratio of more than 70 dB in 361 channels with equal spacing of 25 GHz by applying a bias voltage to a voltage-operated piezoelectric element of a tunable etalon filter. A single longitudinal mode operation of the fiber ring laser can be obtained by using a saturable absorber serving as a narrow-bandwidth filter.

Abstract: A bidirectional amplification system and method are disclosed. A single optical line amplifier and isolation loss filters are used to amplify signals in both the east and west directions with sufficient gain along a fiber. In an embodiment, a first signal propagating in a first direction (e.g., east) from a first port and second signal propagating in a second direction (e.g., west) from a second port are received at an optical amplifier module. The first and second signals are combined into a combined signal propagating in one direction. The combined signal is then amplified. The combined signal is then split into amplified first and amplified second signals. The isolation loss of each amplified signal is increased. Then, the amplified first signal propagating in the first direction is output at the second port and the amplified second signal propagating in the second direction is output at the first port.

Abstract: The present invention includes an apparatus and the method to scale the average power from high power ultra-short pulsed lasers, while at the same time addressing the issue of effective beam delivery and ablation, by use of an optical amplification system.

Abstract: A system and method is provided for uniform illumination of a target area. In one embodiment, the system comprises a plurality of mutually incoherent light sources configured to generate respective light beams with different wavelengths, and transmitting optics configured to transmit the light beams with different wavelengths in a non-overlapping wavelength light beam pattern over the target area, such that there are no overlap regions of the target area illuminated by a light beam from the same light source.

Abstract: Disclosed is an optical fiber that includes an inner core having a concentration of at least one laser active material, the inner core being adapted to operate in a single mode manner; and an outer core disposed about the inner core having a concentration of at least one laser active material. The outer core being adapted to operate in a multimode manner, a cladding disposed about the outer core; and an outer cladding is disposed about the cladding adapted to substantially confine pump light within the cladding.

Abstract: To extend the temperature range for a stable operation without mode hopping and obtain a stable laser oscillation, a laser oscillator is provided. The laser oscillator includes: an optical circulator in which light incident on a first port is exited from the second port, light incident on the second port is exited from a third port, and light incident on a fourth port is exited from the first port; a first optical amplification fiber that amplifies the light exited from the third port because of being excited by an exciting light and injects the same into the first port; a reflective optical filter that reflects light with a predetermined wavelength among the light exited from the second port and injects the same into the second port again; and an pump light source that generates an exciting light to excite the first optical amplification 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 electronic device is provided that includes a first component generating heat, a second component to be heated, a heating part configured to heat the second component, and a case containing the first component, the second component, and the heating part. The second component is heated with the heating part and the heat generated by the first component.

Abstract: Fiber light amplifiers adapted for high power application are provided. In embodiments of the invention, the light signal to be amplified is coupled to a cladding mode of an active waveguide region which is cladding doped. The amplified light is coupled to an output fiber have waveguiding properties matching those of the active cladding of the active waveguide region. In other embodiments, two or more amplifying stages are provided coupled by a wavelength selective loss element which couples the Stokes wave co-propagating with the signal to be amplified out of the signal guiding mode prior to the onset of SRS.

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: A processing method for suppressing photodarkening in an Yb-doped optical fiber, comprising: a first step of preparing the Yb-doped optical fiber by doping a core with Yb, and irradiating at least one of a gamma ray, a X-ray, or an electron beam onto the Yb-doped optical fiber with an energy greater than a light to be transmitted through the optical fiber when a laser is being oscillated; a second step of measuring a loss spectrum of an infrared region of the optical fiber after the first step, and selecting an optical fiber with the loss in a specific wavelength falling within a predetermined range; and a third step of treating the optical fiber selected in the second step in an atmosphere containing hydrogen to obtain an Yb-doped optical fiber with suppressed photodarkening.

Abstract: The invention relates to a variable embodiment of a grating waveguide structure, based on a planar thin-film waveguide with a first optically transparent layer (a) on a second optically transparent layer (b) having a lower refractive index than layer (a), and a grating structure (c) modulated in layer (a), wherein the intensity of an excitation light irradiated at the resonance angle for incoupling into layer (a) is enhanced by at least a factor of 100 on layer (a) and within layer (a), at least in the region of the grating structure (c), in comparison with the intensity of said excitation light on a substrate surface without incoupling of the excitation light. The invention also relates to an optical system with an excitation light source and an embodiment of a grating waveguide structure according to the invention, and to a method for enhancing an excitation light intensity, and to the use thereof in bioanalytical detection processes, in non-linear optics or in telecommunications or communications industry.

Abstract: A guiding nonlinearity cell. The novel nonlinearity cell includes a nonlinear medium and a waveguide adapted to guide input electromagnetic energy through the nonlinear medium. In an illustrative embodiment, the cell includes a thin layer of a liquid or solid nonlinear medium disposed between two parallel plates adapted to guide energy through the length of the medium by total internal reflection. The plates can be made from a material having a refractive index less than a refractive index of the medium to provide total internal reflection within the liquid, or they can be made from a material matching the refractive index of the medium such that outer walls of the plates provide total internal reflection, allowing energy to leak into the plates.

Abstract: The invention relates to an optical pulse amplifier comprising a first optical fiber amplifier adapted to receive an input pulse, a splitter connected to said first optical fiber, said splitter having a plurality of outputs; a plurality of optical fiber amplifiers, each optical fiber amplifier being connected to one of said plurality of outputs, said plurality of optical fiber amplifiers generating a plurality of output pulse signals. The optical pulse amplifier of the invention has the advantage that it can produce high peak and high average power.

Abstract: A wavelength conversion device that obtains, from an input light, a wavelength-converted light with a wavelength shift by a wavelength shift amount of ?? is disclosed. The device comprises first and second wavelength converters. The first wavelength convertor shifts a central wavelength of a first wavelength-converted light by a first wavelength shift amount of ??1 relative to a central wavelength of an input light. The second wavelength convertor shifts a central wavelength of a second wavelength-converted light by a second wavelength shift amount of ??2 relative to a central wavelength of the first wavelength-converted light. The first wavelength shift amount of ??1 and the second wavelength shift amount of ??2 satisfy ??1+??2=??.

Abstract: A photonic bandgap fiber includes a core of a solid material; a first cladding provided around the core; a low-refractive-index region provided in a part of a core vicinity portion of the first cladding and whose average refractive index is lower than that of the core; and a periodic structure region that is arranged in another part of the core vicinity portion of the first cladding which is made of a great many high-refractive-index portions whose refractive index is higher than that of the first cladding arranged in a periodic structure. According to the invention, it is possible to provide a photonic bandgap fiber which, when arranged in a double-clad structure, enables pump light to efficiently pump signal light.

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: Methods and systems for compensation of Self-Phase Modulation 35 in fiber-based amplifier systems 20.

Abstract: A chirped pulse amplifier (CPA) system having a mode-locked laser and a high-speed pulse selector, wherein the pulse selector modulates output pulses based upon an applied modulation voltage. A pulse selector may be an integrated electro-optic modulator, for example a LiNbO3 modulator, or an electro-absorption modulator. Difficulties related to free-space alignment and operational stability of some prior designs are reduced or eliminated. Fiber coupling generally simplifies beam delivery and alignment. Some embodiments include an erbium fiber (or erbium-ytterbium) based CPA system operating at a wavelength of approximately 1550 nanometers. Similar performance can be obtained at other wavelengths, for example a 1.06 .micrometer Yb-doped fiber system. Moreover, high amplification and peak intensity at the output may be achieved while avoiding non-linear effects in the pulse selector, thereby providing for high intensity picosecond or femtosecond operation.

Abstract: A high power fiber amplifier including a double clad fiber including a protective outer jacket (41), an outer clad (44), an inner clad (42, 35) and a doped core (43, 34, 32), and a source of pump power coupled to the inner clad through coupling optics (22) and at least one of a side-fiber coupling section and an end-fiber coupling section, wherein the inner clad includes a large diameter core portion (34), operative as a high power amplification stage, capable of absorbing the majority of the pump power, and a small diameter core portion (32), operative as a low power amplification stage, wherein both core portions, pumped through the inner clad (35), are serially connected through an optical interface point (37).