Abstract: The present invention discloses a device and method for controlling a lasing wavelength of a tunable laser, and a wavelength division multiplexed-passive optical network having the same. In a device and method for controlling a lasing wavelength of a tunable laser, and a wavelength division multiplexed-passive optical network having the same, it is possible to improve performance of the wavelength division multiplexed-passive optical network by automatically controlling a lasing wavelength of a tunable laser to be matched with a transmission wavelength of a wavelength division multiplexer/de-multiplexer using optical power or optical beating components obtained by a reflected optical component which is Raleigh backscattered or reflected, and is generated on an optical fiber.

Abstract: Embodiments of the present invention describe systems and methods for delivering ultrashort laser pulses through an optical fiber system with higher order mode fiber output and without pre-chirping. In one embodiment of the present invention, an all-fiber delivery system comprises a mode-locked solid-state or fiber laser for generating laser pulses in the 0.2 ?m to 1.3 ?m wavelength range, a single mode fiber with normal dispersion, and a long-period-grating mode converter, and a higher order mode fiber with anomalous dispersion, wherein the all-fiber delivery system is free of bulk optics, and propagates laser pulses without pulse pre-chirping, and wherein higher order mode output beam from the all-fiber delivery system comprises pulses at less than about 200 femtoseconds.

Abstract: A laser system for generating optical pulses at an operating wavelength of the laser system. The system has an optical resonator comprising first and second reflectors, and a tapered optical fiber disposed between the first and second reflectors. The tapered optical fiber has a core which has a tapered input section which tapers from single mode to multimode at the laser operating wavelength, an inner section of substantially constant diameter capable of supporting multiple modes at the laser operating wavelength. The tapered optical fiber can include a tapered output section wherein the core tapers from a first diameter to a second diameter that is smaller than the first diameter.

Abstract: The invention relates to a double-sheath fiber having a core region (1) and a sheath region, the sheath region having an inner region (2) and an outer region (3), which comprises a refractive index that is lower with respect to that of the inner region (2) and the core region (1), wherein the outer region (3) surrounds the inner region (2). The invention proposes an internal structure (4) of the inner region (2) which effects a spatial overlap of modes of higher order with the core region (1), which is lower than the spatial overlap of a fundamental mode with the core region (1).

Abstract: We have demonstrated a novel Sagnac loop and micro-ring based laser cavity which is simple and reliable, with accurately controlled reflectivity and negligible excess loss. The resonant wavelength of a 2 ?m radius micro-ring is shown to be lithographically controlled to a standard deviation of 3.6 nm. Both C- and O-Band lasers based on Sagnac loop mirror and micro-ring cavity have been demonstrated. The lasers are shown to be able to be modulated at 40 Gb/s.

Abstract: An optical fiber connector for transmitting high optical power, specifically power exceeding 1 kW. The connector includes an optical fiber having one of its ends in direct optical contact with a body made of a transparent material. The body in connection with the optical fiber end has a surface with an area exceeding the contact surface area of the optical fiber. The surface of the transparent body has a substantially conical design in order to provide an efficient flowing geometry around the contact end of the fiber, to increase the surface area for incident power loss radiation and deviate such radiation towards the optical axis of the connector.

Abstract: An exemplary illumination source for an inspection system includes a pulsed seed laser having a wavelength of approximately 1104 nm and a continuous wave, Raman seed laser having a wavelength of approximately 1160 nm. An optical coupler can combine outputs of the pulsed seed laser and the continuous wave, Raman seed laser. Pre-amplification stages can receive an output of the optical coupler. A power amplifier can receive an output of the pre-amplification stages. A sixth harmonic can be generated using the amplified, combined wavelength. Systems for inspecting a specimen such as a reticle, photomask or wafer can include one of the illumination sources described herein.

Abstract: A laser system for semiconductor inspection includes a fiber-based fundamental light source for generating fundamental light that is then converted/mixed by a frequency conversion module to generate UV-DUV laser light. The fundamental light source includes a nonlinear chirp element (e.g., a Bragg grating or an electro-optic modulator) that adds a nonlinear chirp to the seed light laser system prior to amplification by the fiber amplifier(s) (e.g., doped fiber or Raman amplifiers). The nonlinear chirp includes an x2 or higher nonlinearity and is configured to compensates for the Self Phase Modulation (SPM) characteristics of the fiber-based amplifiers such that fundamental light is generated that has a spectral E95 bandwidth within five times that of the seed light. When multiple series-connected amplifiers are used, either a single nonlinear chirp element is provided before the amplifier string, or a chirp elements are included before each amplifier.

Abstract: A laser fiber has a distal end having a laser fiber face. A tip addition is attached to or formed onto the fiber face. The material of the tip addition one of fragments or melts when laser energy from a suitable laser device is passed through the laser fiber and through the tip addition.

Abstract: Frequency standards based on mode-locked fiber lasers, fiber amplifiers and fiber-based ultra-broad bandwidth light sources, and applications of the same.

Abstract: A high power fiber laser system emitting a substantially diffraction limited beam with a Gaussian intensity profile includes a single mode (“SM”) neodymium fiber pump source outputting a SM pump light; a seed laser operative to emit a SM signal light at a wavelength greater than that of the pump light; a SM DWM receiving and multiplexing the SM pump and signal lights. The disclosed system further includes a booster fiber amplifier which is configured with a frustoconically-shaped ytterbium (“Yb”) doped core receiving the pump and signal lights and configured with a small diameter input end which supports only a SM and a large diameter output end which is capable of supporting the SM and high order modes (:HOM”). The booster further has a cladding surrounding and coextending with the core, the core being configured for having intensity profiles of respective SMs of pump and signal lights overlap one another so that an overlap integral substantially equals to one (1) along an entire length of the core.

Abstract: An optical active fiber is configured with an asymmetrically-shaped core having at least one long axis and a shortest axis which extends transversely to the long axis. The outmost cladding of the active fiber is configured with a marking indicating the orientation of the short axis. The marking allows for bending the fiber so that the shortest axis extends along and lies in the plane of the bend thereby minimizing distortion of a mode which is guided by the asymmetrically-shaped core as light propagates along the bend.

Abstract: Embodiments relate to an all fiber passively Q-switched laser. The laser includes a large core doped gain fiber having a first end. The large core doped gain fiber has a first core diameter. The laser includes a doped single mode fiber (saturable absorber) having a second core diameter that is smaller than the first core diameter. The laser includes a mode transformer positioned between a second end of the large core doped gain fiber and a first end of the single mode fiber. The mode transformer has a core diameter that transitions from the first core diameter to the second core diameter and filters out light modes not supported by the doped single mode fiber. The laser includes a laser cavity formed between a first reflector positioned adjacent the large core doped gain fiber and a second reflector positioned adjacent the doped single mode fiber.

Abstract: Implementations and examples of fiber lasers based on fiber laser cavity designs that produce self-similar pulses (“similaritons”) to achieve a pulse spectral bandwidth greater than a gain spectral bandwidth based on a spectral broadening fiber segment and a spectral filter to ensure the proper similariton conditions.

Abstract: A fiber-based supercontinuum system including: a pump laser; a ZBLAN or other fluoride-based microstructured glass fiber; and control electronics; wherein the control electronics control the pump laser to generate laser pulses into the ZBLAN or other fluoride-based microstructured glass fiber. The fabrication of a ZBLAN photonic crystal fiber with sub-micron features and large air-filling fraction and the use of the fiber to generate a stable supercontinuum (200 to 2500 nm) from 140 fs, 1 nJ pulses at 1042 nm are disclosed.

Abstract: Optical pulse source comprising optical pump laser for generating optical pump pulses at repetition rate Rf; a nonlinear optical element comprising an optical fiber for generating supercontinuum pulses; a gating device provided operable to selectively control the launch of pump pulses into the optical fiber at a reduced, lower repetition rate Rr=Rf/N in order to generate supercontinuum pulses at different user selectable repetition rates lower than the pump pulse repetition rate; first and second optical amplifiers; wavelength tunable optical bandpass filter; wherein the optical fiber can generate supercontinuum pulses having a supercontinuum spanning from below 450 nm to greater than 2000 nm; and wherein said optical pulse source comprises an all-fiber source wherein said optical pump laser comprises a fiber oscillator, said gating device comprises a fiber coupled optical modulator, and the optical pump pulses are launched into the optical fiber without the use of free space optics.

Abstract: A tunable fiber ring laser with a gain clamped semiconductor optical amplifier is a ring laser source working at room temperature. The laser has an inner cavity disposed inside an outer cavity. A pair of circulators disposed in the inner cavity is configured to assure counter-propagation of light between the inner cavity and the outer cavity. A gain-clamped semiconductor optical amplifier (GC-SOA) is formed by combining a semiconductor optical amplifier (SOA) and a fixed filter in conjunction with the pair of circulators. A Fiber Fabry-Perot Tunable Filter (FFP-TF) is disposed in the outer cavity and connects to the pair of circulators via a polarization controller and a fused coupler.

Abstract: The invention relates to a short pulse laser (1) having a first optical plate (3) on which a seed laser oscillator (4), a pulse picker (5), and a fiber coupling-in optical unit (6) are mounted so as to be mechanically stable in relation to one another, and second optical plate (7), which is separate from the first optical plate (3) and on which a fiber coupling-out optical unit (9) and at least one amplifier stage (8, 30, 31) are mounted so as to be mechanically stable in relation to one another. The fiber coupling-in optical unit (6) of the first optical plate (3) and the fiber coupling-out optical unit (9) of the second optical plate (7) are optically interconnected by a flexible light guiding element (10). The hybrid short pulse laser (1) has a compact design and can be operated at low cost.

Abstract: A CW ytterbium-doped fiber-laser includes a gain-fiber having a reflector proximity-coupled to one end, with the other end left uncoated. A laser resonator is defined by the reflector and the uncoated end of the gain-fiber. Pump-radiation from fast-axis diode-laser bar-stacks emitting at 915 nm and 976 nm is combined and focused into the uncoated end of the gain-fiber for energizing the fiber. Laser radiation resulting from the energizing is delivered from the uncoated end of the gain-fiber and separated from the pump-radiation by a dichroic mirror.

Abstract: A normal-dispersion fiber laser is operated using parameters in which dissipative solitons exist with remarkably large pulse duration and chirp, along with large pulse energy. A low-repetition-rate oscillator that generates pulses with large and linear chirp can thus replace the standard oscillator, stretcher, pulse-picker and preamplifier in a chirped-pulse fiber amplifier.

Abstract: A system and method for adjusting the coherence length of a tunable laser to optimize measurements and reduce artifacts. A tuning element of the laser system modulates, adjusts, or controls parameters associate with the tunable laser, such that the output wavelength of the tunable laser is modulated or adjusted over a wavelength range within a time interval. Modulation of the parameter has the effect of increasing a linewidth of the tunable laser.

Abstract: A double-clad (DC) multicore (MC) Erbium-doped fiber amplifier (EDFA) for dense-wavelength-division multiplexing (DWDM) is disclosed. The DC-MC-EDFA comprises a length of DC-MC Erbium-doped fiber (EDF) that is core-matched spliced to a MC tapered signal-pump fiber combiner (TFC). For some embodiments, the optical signals are coupled into the DC-MC-EDF by the MC-TFC, and the pump energy is also coupled into the DC-MC-EDF by the MC-TFC. For some embodiments, the optical signals are also transmitted out of the DC-MC-EDF through the MC-TFC.

Abstract: A tunable light includes a super continuum light source and a non-linear crystal, the super continuum light source comprising a pump source and a generator fiber, the generator fiber having an input end and an output end, and the super continuum light source and the non-linear crystal being arranged so that at least a part of output light emitted from the output end of the generator fiber is brought into interaction with the non-linear crystal under an angle of incidence ? relative to a surface of the non-linear crystal.

Abstract: The invention relates to a pulsed light source capable of effectively utilizing optical power and selecting the pulse width of output pulsed light. A pulsed light source has a MOPA structure, and comprises a seed light source and an optical fiber amplifier. The seed light source includes a semiconductor laser outputting pulsed light. In the optical fiber amplifier, an optical filter branches pulsed light amplified by a YbDF into a first wavelength component including the peak wavelength and the remaining second wavelength component. An optical switch outputs one of the pulsed light of the first wavelength component and the pulsed light of the second wavelength component which are inputted. Another YbDF amplifies the pulsed light outputted from the optical switch.

Abstract: An excitation unit for a fiber laser having an excitation fiber and forming a two-dimensional or three-dimensional structure in a resonator region of the fiber laser. In cross-section, the excitation fiber has an active fiber core, a pump cladding that surrounds the active core, a quartz glass casing that surrounds the pump cladding, and at least one cover. The resonator region is equipped with a base plate having a plurality of excitation housings, each housing delimiting a gas-tight excitation chamber. The excitation fiber runs through each excitation chamber and is held in holding units. The excitation chambers are formed in an elliptical manner. The excitation housings are provided with a translucent window, and a transversal pump light source is arranged in the region of each translucent window such that a pump light that leaves the pump light source impinges the longitudinal axis of the excitation fiber in a perpendicular manner.

Abstract: The device is proposed which provides mode-locked operation of a fiber laser. The principle of its operation is based on a focusing effect of Kerr lens. At high intensities of the light beam the Kerr element exhibits light focusing properties. The beam focused by the Kerr element enters a fiber core without losses thus providing an effective generation of mode-locked laser. In the preferred embodiment the Kerr element is positioned at one degree relative to a perpendicular to the beam direction.

Abstract: The present application discloses a laser source for emitting laser light onto a work-piece. The laser source includes a generator configured to generate the laser light, and an adjuster configured to adjust an output of the laser light. The adjuster situated between the generator and the work-piece reduces output density of the laser light on the work-piece.

Abstract: An apparatus for generating a pulse train with an adjustable time interval is provided. The apparatus, being an annular optical cavity structure, includes a seed source receiving end, a pump source receiving end, an optical coupler, an optical combiner, a gain fiber, an optical path time regulator and a beam splitter. Thus, the apparatus is capable of generating a pulse train with an adjustable time interval to increase material processing quality and speed.

Abstract: An ultrashort pulse laser processing apparatus for processing a processing target includes: a laser head which includes a seed laser source emitting an ultrashort pulse seed laser, and emits a laser pulse; an optical fiber which guides the laser pulse emitted from the laser head; and an emission end unit which includes a compressor that compresses the laser pulse emitted from the optical fiber to a laser pulse of a predetermined high peak power and emits the laser pulse compressed by the compressor to the target.

Abstract: A light source system for delivery of light including a light source having an output arranged to emit light in an output path, the output path including an unguided section and an at least partially transmissive optical component wherein the optical component provides at least one residual reflection when the system is in use and a detector system is arranged to detect said residual reflection. The detector is in one embodiment arranged to produce at least one feedback response arranged to stabilize the optical output of the light source system. Hereby a feedback may be implemented with little or no reduction of performance.

Abstract: The invention relates to a laser device (1) for amplifying and/or transporting electromagnetic radiation, comprising a radiation source (2) for generating the electromagnetic radiation and an amplifier (4) for amplifying or a medium for transporting the generated electromagnetic radiation. In order to make available a device (1) for amplifying or transporting electromagnetic radiation that provides a very easy to implement possibility for reducing the influence of non-linear effects, the electromagnetic radiation propagating in the amplifier (4) or medium is largely non-linearly polarized.

Abstract: A system and method for producing Stimulated Raman Scattering (SRS) is disclosed. A single optical fiber or Raman oscillator is optically pumped by a pump laser of sufficient power to generate SRS to generate several Stokes shifts of energy. This generates a multi-wavelength output or a single wavelength with several stokes energy shifts from the pump wavelength. A selective, monolithic-coated Raman fiber oscillator laser is utilized to increase the efficiency of frequency shifting by providing frequency-specific feedback at both facets of a free space coupled optical fiber oscillator. Frequencies that lie several bands away from the primary pump frequency may be efficiently achieved in a fiber oscillator by re-circulating the required stokes-shifted frequencies via selective high-reflection coatings. By re-circulating the intra-band stokes frequencies, the required intensities in each respective frequency will be increased, thereby dropping the respective Raman threshold in the optical fiber.

Abstract: In at least one embodiment a laser system includes a fiber laser source, a polarization controller and a wavelength converter. The relative power distribution between a pump wavelength and a signal wavelength is controllable using the polarization controller. An optional phase compensator is used to control polarization state of the output laser beam. In various embodiments the relative power distribution among multiple wavelengths may be controlled over a range of at least about 100:1.

Abstract: Methods and systems for generating ultrafast, high energy, high power fiber laser pulses are disclosed, including generating a sequence of signal laser pulses from a broadband, mode locked, seed fiber laser oscillator; using a pulse stretcher to stretch the signal laser pulses; using a pulse picker to down select the stretched laser pulses; using a wavelength separator to separate the down selected laser pulses into two or more wavelength channels; using two or more delays lines to independently adjust for time differences between the laser pulses of the two or more wavelength channels; using two or more amplifier chains to amplify the delay line adjusted laser pulses; using a wavelength combiner to combine the amplified laser pulses; and using a compressor to compress the combined laser pulses to emit an ultrafast, high energy, high power laser pulse. Other embodiments are described and claimed.

Abstract: Techniques are disclosed for improving pump absorption and efficiency for fiber lasers and amplifiers, for instance. In some embodiments, the techniques are implemented by applying a partially reflective coating on a fiber end-face to double-pass any unabsorbed or otherwise excess pump light in the cladding of a fiber. While being reflective to pump wavelengths, the coating can be non-reflective at the lasing wavelength, so as to avoid unwanted feedback into the system. The benefits of this approach include that excess pump power can be effectively utilized to add more power to the laser output. In addition, the double-pass technique allows for the use of a shorter fiber length, which in turn allows for more compact system designs, saves on material costs, and facilitates manufacturability.

Abstract: A laser device includes a seed laser, a polarizer, a pseudorandom bit sequence (PRBS) pattern generator, and a phase modulator. The polarizer may be optically coupled to receive an output of the seed laser and may generate a polarization filtered output. The PRBS pattern generator may be configured to generate a PRBS pattern. The phase modulator may be configured to apply a PRBS modulation scheme to the polarization filtered output based on the PRBS pattern. The PRBS pattern may be generated to have a length above a first threshold for avoiding an occurrence of backward propagation being in phase with forward propagation in an active fiber receiving an output of the phase modulator when the pattern repeats and below a second threshold for phase mismatch in the active fiber.

Abstract: Techniques and architecture are disclosed for controlling the temperature of a fiber laser system. In some embodiments, a single thermoelectric cooler (TEC) may be utilized to control the temperature of multiple system components. In some embodiments, a TEC may be physically/thermally coupled to a laser diode, which in turn may be physically/thermally coupled with a mounting plate to which one or more fiber grating holders are physically/thermally coupled, and an optical fiber that is operatively coupled with the laser diode may be physically/thermally coupled with the one or more fiber grating holders. In some embodiments, this may provide a thermal pathway/coupling between the optical fiber (e.g., its fiber grating(s)), and the TEC. In some embodiments, this may reduce/minimize the quantity of temperature control components, reduce system size/complexity, increase system dependability, and/or increase system performance/efficiency.

Abstract: Coherent and compact supercontinuum light sources for the mid IR spectral regime are disclosed and exemplary applications thereof. The supercontinuum generation is based on the use of highly nonlinear fibers or waveguides. In at least one embodiment the coherence of the supercontinuum sources is increased using low noise mode locked short pulse sources. Compact supercontinuum light sources can be constructed with the use of passively mode locked fiber or diode lasers. Wavelength tunable sources can be constructed using appropriate optical filters or frequency conversion sections. Highly coherent supercontinuum sources further facilitate coherent detection schemes and can improve the signal/noise ratio in lock in detection schemes.

Abstract: A fibre laser having an optical cavity that has an optical fibre and a curved mirror for imaging light leaving the fibre back into the fibre. The optical fibre has a round trip dispersion loss of less than 200000 fs2. The round trip length of the optical fibre is less than 2.3 m.

Abstract: A laser system for semiconductor inspection includes a fiber-based fundamental light source for generating fundamental light that is then converted/mixed by a frequency conversion module to generate UV-DUV laser light. The fundamental light source includes a nonlinear chirp element (e.g., a Bragg grating or an electro-optic modulator) that adds a nonlinear chirp to the seed light laser system prior to amplification by the fiber amplifier(s) (e.g., doped fiber or Raman amplifiers). The nonlinear chirp includes an x2 or higher nonlinearity and is configured to compensate for the Self Phase Modulation (SPM) characteristics of the fiber-based amplifiers such that fundamental light is generated that has a spectral E95 bandwidth within five times that of the seed light. When multiple series-connected amplifiers are used, either a single nonlinear chirp element is provided before the amplifier string, or chirp elements are included before each amplifier.

Abstract: A laser system includes an injection laser source having an output and operable to provide a laser output characterized by a first wavelength, a first linewidth, an output power. The laser system also includes a tunable pulsed source characterized by a gain bandwidth. The tunable pulsed source is operable to provide an output signal having an average power. The output signal includes a plurality of optical pulses. Each of the plurality of optical pulses is characterized by a second wavelength, a second linewidth, and a peak power. The laser system further includes an optical combiner having a first port coupled to the output of the injection laser source, a second port coupled to the tunable pulsed source, and a third port.

Abstract: The present invention relates to a Q-switching-induced gain-switched erbium pulse laser system, capable of generating erbium laser pulses within the 2.5 ?m to 3.0 ?m wavelength region, by means of Q-switching operation at 1.6 ?m. At first, an Er3+-doped gain medium is pumped and Q-switched at the wavelength region from 1.58 ?m to 1.62 ?m, so that a Q-switched pulse is formed from the Er3+-doped gain medium. The Q-switched pulse results in an instant positive population inversion between the levels 4I11/2 and 4I13/2 of the Er3+-doped gain medium, followed by a gain-switched laser pulse at the wavelength region from 2.5 ?m to 3.0 ?m.

Abstract: The method generally has the steps of propagating a seed wave in an optical fiber; generating a wave of first order by stimulated Brillouin scattering of the seed wave in the optical fiber, the wave of first order having a frequency spectrally shifted from the seed wave and being backscattered from the seed wave; propagating the seed wave and the wave of first order in a feedback cavity thereby generating a plurality of waves of higher order, each wave of higher order being cascadely generated by the wave of previous order, each wave of higher order being backscattered and having a frequency spectrally shifted from its corresponding wave of previous order and forming a frequency comb with the seed wave and the wave of first order; the frequency comb generating optical pulses; and propagating the generated optical pulses out of the feedback cavity.

Abstract: A high power fiber laser system consisting of multiple fiber amplifier or laser systems amplifying the input signal in parallel is configured with a high power splitter such as to share some of the gain stages. The high power splitting component consists of high power fiber couplers and splitter(s). The splitter is a holographic optical element, a dielectric coated plate, a diffraction grating, or a volume Bragg grating. The resultant fiber laser configuration reduces the total number of amplifying stages including optical isolators and active fiber assemblies for the system and thus reduces the total volume and weight.

Abstract: An apparatus, method and associated fiber-laser architectures for high-power pulsed operation and pumping wavelength-conversion devices. Some embodiments generate blue laser light by frequency quadrupling infrared (IR) light from Tm-doped gain fiber using non-linear wavelength conversion. Some embodiments use a fiber MOPA configuration to amplify a seed signal from a semiconductor laser or ring fiber laser. Some embodiments use the frequency-quadrupled blue light for underwater communications, imaging, and/or object and anomaly detection. Some embodiments amplitude modulate the IR seed signal to encode communication data sent to or from a submarine once the modulated light has its wavelength quartered.

Abstract: The invention is an apparatus and method for free space pumping of active double-clad fiber based lasers and amplifiers. The apparatus comprises a laser emitting a signal laser beam; an active double-clad fiber having a core defining an optical axis of the apparatus and a pump cladding defining a cone of numerical aperture; an optical arrangement directing the signal laser beam along the optical axis through the core of the active double-clad fiber; at least one pump source emitting a pump beam; at least one delivery means coupling the pump beam to the pump cladding of the active double-clad fiber; and an optical arrangement coupling the amplified signal laser beam exiting the active double-clad fiber out of the apparatus.

Abstract: Holey fibers provide optical propagation. In various embodiments, a large core holey fiber comprises a cladding region formed by large holes arranged in few layers. The number of layers or rows of holes about the large core can be used to coarse tune the leakage losses of the fundamental and higher modes of a signal, thereby allowing the non-fundamental modes to be substantially eliminated by leakage over a given length of fiber. Fine tuning of leakage losses can be performed by adjusting the hole dimension and/or spacing to yield a desired operation with a desired leakage loss of the fundamental mode. Resulting holey fibers have a large hole dimension and spacing, and thus a large core, when compared to traditional fibers and conventional fibers that propagate a single mode. Other loss mechanisms, such as bend loss and modal spacing can be utilized for selected modes of operation of holey fibers.

Abstract: A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity.

Abstract: An optical fiber which includes a core region embedded within a cladding. The core region of the optical fiber further comprises multiple sections, each doped with rare earth ions.

Abstract: The invention provides fiber-optic light sources such as cladding-pumped master oscillator—power amplifier (MOPA) systems which use double-clad optical fibers (DCF). The inner cladding of the first DCF used in the master oscillator section has a circular cross-section in order to enable the formation of low loss optical splices in the integrated MOPA structure. The inner cladding of the second DCF in the output amplifier section has a shaped non-circular cross-section in order to enhance the absorption of the pump light in the doped core of the second DCF.