Abstract: Systems and methods for monitoring signals in an optical fiber amplifier system are provided. The optical amplifier system includes a tapered fiber bundle which couples optical energy into the cladding of an optical amplifier. A signal passing through the optical amplifier is amplified. To monitor the amplified signal, a single fiber of a tapered fiber bundle may be used as a monitor fiber. Alternatively, a monitor or coupler may be integrated into the tapered fiber bundle during manufacturing. The systems and methods disclosed allow for monitoring the amplified signal without increasing the length of the amplified signal's path, thus minimizing the introduction of additional non-linearities.

Abstract: Doped fiber amplifiers (DFA) using rare-earth doping materials with linear and non-linear interactions between the optical signal to be amplified and the pump laser have become a standard element of optical telecommunications systems for multiple applications including for example extending the reach of optical links before opto-electronic conversion is required or support increased fanout. However, in many applications wherein multiple DFAs are employed the electrical power budget wherein the pump laser diode (LD) represents approximately 25% of the module power consumption directly, and closer to approximately 40-50% once the control and drive electronics for the thermoelectric cooler and LD are included. Accordingly, it would be beneficial to reduce the overall power consumption of a DFA by exploiting unused optical pump power such that multiple gain stages, within the same or different DFAs, may be driven from a single pump LD.

Abstract: A method of operating a fiber amplifier characterized by a spectral gain curve includes providing an input signal at a signal wavelength. The signal wavelength lies within an in-band portion of the spectral gain curve extending from a first in-band wavelength to a second in-band wavelength, the in-band portion being characterized by a first amplitude range. The method also includes providing pump radiation at a pump wavelength. The pump wavelength is less than the signal wavelength. The method further includes coupling the pump radiation to the fiber amplifier and amplifying the input signal to generate an output signal. All portions of the spectral gain curve at wavelengths less than the first in-band wavelength and greater than the pump wavelength are characterized by a second amplitude less than or equal to 10 dB greater than the first amplitude range.

Abstract: A reconfigurable optical amplifier is formed of a plurality of optical switches and a plurality of fiber amplifier sections to provide a switchable amplifying network. A variable pump splitter provides pump light from an optical pump source to two or more fiber amplifier sections. The optical switches and variable pump splitters are formed in a planar lightwave circuit, which may further include pump WDM combiners, variable optical attenuators, tap couplers and other optical components, and to which monitoring photodiodes and the fiber amplifier sections are coupled. A same PLC can be used for a wide variety of reconfigurable optical amplifiers.

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: Provided is a compact terahertz-wave generating apparatus that generates terahertz waves at high output and high efficiency. A terahertz-wave generating apparatus includes an electromagnetic-wave resonator including a hollow fiber in which an electromagnetic-wave gain medium is disposed, the electromagnetic-wave gain medium generating terahertz waves when exciting energy is supplied thereto, wherein the terahertz waves are amplified in the electromagnetic-wave resonator and are taken from the electromagnetic-wave resonator, wherein the diameter of the hollow fiber is set at one or more times and ten times or less as large as the inside diameter of the hollow fiber, in which the electromagnetic-wave gain medium is disposed, at which a cutoff frequency in a terahertz-wave propagation mode TE11 is provided.

Abstract: Methods and systems for managing pulse energy scaling are disclosed, including generating electromagnetic radiation; coupling the electromagnetic radiation to a fiber geometrical management system comprising: a tapered fiber comprising: an elliptical or rectangular core centrally positioned within a single or double cladding shell, wherein the core comprises a fiber material and a doped gain medium; an input face wherein the doped core comprises a major axis and a minor axis, wherein the ratio of the major to minor axis at the input face ranges from about 1 to about 100; an output face wherein the doped core comprises a major axis and a minor axis, wherein the ratio of the major to minor axis at the output face ranges from about 1 to about 100; and wherein the major (minor) axis is adiabatically or linearly tapered from the input face to the output face. Other embodiments are described and claimed.

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: An apparatus includes a multi-core optical fiber and first, second, and third optical couplers. The multi-core optical fiber is rare-earth doped to provide optical amplification in response to optical pumping thereof. The first optical coupler is configured to end-couple a first multi-mode optical fiber to an end of the multi-core optical fiber. The second optical coupler is configured to end-couple a second multi-mode optical fiber to an end of the multi-core optical fiber. The third optical coupler is configured to optically couple a pump light source to the multi-core optical fiber.

Abstract: The invention relates to an optical pumping device comprising: a fibre light source emitting controlled radiation having a very high transverse modal quality, with a wavelength shorter than 1000 nm; at least one element consisting of an amplifying material doped with a rare earth dopant; means for introducing a pumping light into said doped amplifying material element; and means for cooling said amplifying material. Said optical pumping device is characterised in that the pumping light is emitted by the fibre light source with an average power of higher than 2 W and a modal quality characterised by an M2<5 factor.

Abstract: An optical amplifier includes an optical gain fiber into which signal light and pump light are input and at least one relative phase shifter is inserted. Preferably, the relative phase shifter is inserted so that the relative phase in the lengthwise direction of the optical gain fiber falls within a predetermined range containing 0.5 ?. Preferably, the optical gain fiber is a highly non-linear optical fiber having a non-linearity constant of at least 10/W/km. Preferably, the dispersion of the optical gain fiber is within the range from ?1 ps/nm/km to 1 ps/nm/km in an amplification band. Preferably, the absolute value of the dispersion slope of the optical gain fiber at a zero dispersion wavelength is no greater than 0.05 ps/nm2/km.

Abstract: Various embodiments include large cores fibers that can propagate few modes or a single mode while introducing loss to higher order modes. Some of these fibers are holey fibers that comprising cladding features such as air-holes. Additional embodiments described herein include holey rods. The rods and fibers may be used in many optical systems including optical amplification systems, lasers, short pulse generators, Q-switched lasers, etc. and may be used for example for micromachining.

Abstract: High power parallel fiber arrays for the amplification of high peak power pulses are described. Fiber arrays based on individual fiber amplifiers as well as fiber arrays based on multi-core fibers can be implemented. The optical phase between the individual fiber amplifier elements of the fiber array is measured and controlled using a variety of phase detection and compensation techniques. High power fiber array amplifiers can be used for EUV and X-ray generation as well as pumping of parametric amplifiers.

Abstract: According to some embodiments a few moded optical fiber includes a glass core structured to provide light amplification at an amplification wavelength and a cladding surrounding the core. According to some embodiments the core of the few moded optical fiber includes a portion that has an average concentration of rare earth dopant which is lower by at least 30%, and preferably by at least 50%, than the average concentration of the rare earth dopant at another portion of the core that is situated further from the core center.

Abstract: A laser device includes: an optical fiber amplifier that amplifies and emits a signal light; a control unit that controls pumping power for pumping the optical fiber amplifier; and a signal light detector that detects signal light being propagated to the optical fiber amplifier or an ASE photodetector that detects light that is emitted from the optical fiber amplifier and that has wavelength for which the gain is higher than for the signal light, wherein the control unit suppresses the pumping power for pumping the optical fiber amplifier, when the intensity of the signal light detected by the signal light detector becomes less than or equal to a predetermined signal reference value, or when the intensity of the spontaneously emitted light detected by the ASE photodetector becomes greater than or equal to a predetermined ASE reference value.

Abstract: Embodiments generally relate to an optical waveguide component configured for operation with amplitude modulated optical signals at a line rate. The optical waveguide component includes a first optical waveguide segment having a first port and a second port; and a plurality of second optical waveguides each forming a closed loop. Each of the second optical waveguides is electromagnetically coupled to the first optical waveguide exactly once, and each of the closed loops has a round trip time. A product of the line rate and each of the round-trip times is equal to or greater than unity.

Abstract: An amplification optical fiber includes a core and a clad which covers the core. The core propagates light having a predetermined wavelength in at least an LP01 mode, an LP02 mode, and LP03 mode and, in the core, when the LP01 mode, the LP02 mode, and the LP03 mode are standardized by a power, in at least a part of a region where an intensity of at least one of the LP02 mode and the LP03 mode is stronger than an intensity of the LP01 mode, an active element which stimulates and emits light having a predetermined wavelength is added with a higher concentration than that in at least a part of a region where the intensity of the LP01 mode is stronger than the intensities of the LP02 mode and the LP03 mode.

Abstract: An optical coupler for coupling optical-pump power into a multimode fiber configured to transport an optical space-division-multiplexed (SDM) signal, the coupling being performed in a manner that enables amplification of the SDM signal in the multimode fiber via a stimulated-emission process or a stimulated Raman-scattering process. The optical coupler can be a part of an optical transmitter configured for co-directional pumping, an optical receiver configured for contra-directional pumping, or a relay station disposed within an optical communication link and configured for either type of pumping. The optical coupler can advantageously be used, e.g., to offset the different degrees of attenuation to which the SDM-signal components corresponding to different guided modes of the multimode fiber are subjected to therein.

Abstract: An optical component includes a multicore optical fiber and an I/O optical fiber. The multicore optical fiber has longitudinally extending cores within a common cladding. The cores are arranged on a circumference of a circle centered at a fiber axis in an end face of the multicore optical fiber. Both end faces of the multicore optical fiber are connected to each other such that the cores of the multicore optical fiber are optically connected to each other. Both end faces of the multicore optical fiber are adapted to rotate relative to each other about the fiber axis.

Abstract: A high-power optical fibre laser includes: an oscillator (1); a pumping laser (5) able to emit a high-power pumping optical radiation beam; and a signal-amplifying optical fibre (3) able to receive the optical source signal and the high-power pumping optical radiation beam so as to generate a high-power laser beam. The pumping laser includes a plurality of pumping multimode laser diodes (7a-7f) and a laser cavity, the laser cavity including a double-clad fibre (4) including: a neodymium-doped monomode waveguide; a fibre Bragg grating (9) forming one end of the laser cavity; and a fibre reflector (11) forming the other end of the laser cavity, the monomodefibre laser being able to generate a laser radiation beam when it is optically pumped by a pumping radiation beam originating from the plurality of pumping laser diodes in order for the laser cavity to emit a high-power pumping laser radiation beam.

Abstract: A laser system includes a seed laser operable to output a seed laser signal along an optical path and a phase modulator disposed along the optical path and operable to receive the seed laser signal. The laser system also includes a phase modulator driver coupled to the phase modulator. A drive signal from the phase modulator driver is operable to produce, as an output from the phase modulator, an unmodulated seed laser signal when the drive signal is associated with a first state and a modulated seed laser signal when the drive signal is associated with a second state. The laser system further includes a fiber amplifier disposed along the optical path and operable to receive the output of the phase modulator. A spectral bandwidth of an output of the fiber amplifier associated with the second state is less than a spectral bandwidth of the output of the fiber amplifier associated with the first state.

Abstract: Modular set is formed by optical module interconnected with control module of electronic system. Optical module is formed by at least two pairs of laser diodes connected in series and including Peltier cooler and thermistor, which are connected to inputs of polarizing fiber combiners, and depolarized outputs of these polarizing fiber combiners are connected to inputs of a wavelengths combiner. Module of the electronic system is formed by a control microprocessor interconnected with direct current power supply source, with PID regulators of laser diodes temperature, a display indicating temperature of individual laser diodes and current flowing through them, and a control panel.

Abstract: A tunable external cavity laser for use as a pump laser in an optical amplifier such as a Raman amplifier or erbium doped fibre amplifier comprising a semiconductor gain device (12) operable to provide light amplification, a diffraction grating (18) for selecting the wavelength of operation of the laser and a MEMs actuator for changing the selected wavelength. A plurality of gain devices can be coupled together to improve the bandwidth or gain of the optical amplifier.

Abstract: Various embodiments described herein include rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes. Such optical fibers and rods may be employed in fiber lasers and amplifiers. The index of refraction of the glass may be substantially uniform and may be close to that of silica in some embodiments. Possible advantages to such features include reduction of formation of additional waveguides within the core, which becomes increasingly a problem with larger core sizes.

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.

Abstract: A method for control of excess pump power in an optical amplifiers is disclosed. In one particular exemplary embodiment the method comprises a state model for the amplifier gain medium ground energy level inversion and a closed loop control tracking a desired degree of excess pump power.

Abstract: The present invention relates generally to devices for the generation and amplification of electromagnetic energy. The present invention relates more particularly to optical fiber devices, such as lasers and amplifiers, useful for generating and amplifying optical energy.

Abstract: Provided is a double clad fiber device. The double clad fiber device includes a double clad fiber, a pump combiner, at least one first laser diode, and at least one second laser diode. The double clad fiber includes a core and a clad. The pump combiner provides pump light to the core and the clad through one end of the double clad fiber, respectively. The at least one first laser diode provides first pump light to the clad through the pump combiner. The at least one second laser diode provides second pump light to the core through the pump combiner.

Abstract: Fiber-amplifier device the light-path of which is devoid of a free-space element. The system device an all-fiber-optic Faraday rotator and isolator. The device has a multicomponent glass optical fiber having a core having a first doping concentration of 55%-85% (wt./wt.) of a first rare-earth oxide and a the isolator includes at least three magnetic cells with throughout bores hosting an optical fiber, the same magnetic poles of two immediately neighboring cells facing each other. The first rare-earth oxide includes one or more of Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3, and Lu2O3.

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 time-interleaved A/D converter apparatus has a primary signal A/D converter circuit group that is time-interleaved with a combination of N A/D converter circuits, a correction signal generation part operable to receive the input analog signal and a 1/m-sampling signal having a speed that is 1/m of a rate of the sampling signal inputted to the primary signal A/D converter circuit group, to extract a dispersion of a transmission line that is immanent in the input analog signal, and to output the dispersion as a dispersion compensation control signal used for digital signal compensation, and a signal processing part operable to convert the N digital signals into one digital signal based upon the dispersion compensation control signal and to compensate a dispersion included in the converted digital signal.

Abstract: An optical amplification device includes a first optical amplification portion, an intermediate portion and a second optical amplification portion. The first optical amplification portion receives input light including signal light and pump light, generates idler light as wavelength converted light based on wavelengths of the signal light and the pump light, and outputs first output light including signal light, pump light and idler light. The intermediate portion outputs second output light, and includes a demultiplexing portion that demultiplexes the first output light into signal light, pump light and idler light, a multiplexing portion that generates the second output light by multiplexing signal light, pump light and idler light, and a polarization plane adjustment portion that exchanges mutually orthogonal polarization components of idler light. The second optical amplification portion amplifies an intensity of signal light included in the second output light.

Abstract: A planar optical waveguide amplifier includes an active optical waveguide (203) containing rare-earth ions embedded in a passive optical waveguide (202) that guides the pump power.

Abstract: An optical component includes: a glass capillary; an optical fiber for light to be measured which is inserted into the through-hole of the glass capillary; at least one optical fiber for leak light which is inserted into the through-hole of the glass capillary; and an output optical fiber having one end connected to one end of the optical fiber for light to be measured, wherein light emitted from the output optical fiber enters into the optical fiber for light to be measured from the one end side thereof, and a part of light that has been emitted from the output optical fiber that does not enter into the optical fiber for light to be measured, that is, leak light enters into the optical fiber for leak light from the one end side thereof.

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.

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: The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

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 Raman amplifier using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, to output pumping lights having different central wavelengths, an interval between adjacent central wavelengths greater than 6 nm and smaller than 35 nm. An optical repeater is adapted to compensate loss in an optical fibre transmission line by the Raman amplifier. A Raman amplification method wherein the shorter the central wavelength of the pumping light, the higher light power of the pumping light. In the Raman amplifier, a certain pumping 1 wavelength being a first channel, and second to n-th channels are arranged with an interval of about 1 THz toward a longer wavelength side, pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source.

Abstract: Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: Various embodiments of optical fiber designs and fabrication processes for ultra small core fibers (USCF) are disclosed. In some embodiments, the USCF includes a core that is at least partially surrounded by a region comprising first features. The USCF further includes a second region at least partially surrounding the first region. The second region includes second features. In an embodiment, the first features are smaller than the second features, and the second features have a filling fraction greater than about 90 percent. The first features and/or the second features may include air holes. Embodiments of the USCF may provide dispersion tailoring. Embodiments of the USCF may be used with nonlinear optical devices configured to provide, for example, a frequency comb or a supercontinuum.

Abstract: A pump unit (402) for a Raman amplifier (400) including an optical fibre (401) carrying an optical signal (420) is disclosed. The pump unit includes at least two light sources (411, 412, 431, 432) for emitting light at different wavelengths into the fibre to induce Raman gain of the optical signal passing along the fibre, and a controller (409) for providing pulses to each of the light sources to control when they do and do not emit light. The controller is configured to control the width of the pulses to control the total power of the light emitted into the fibre.

Abstract: Various embodiments described herein include rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes. Such optical fibers and rods may be employed in fiber lasers and amplifiers. The index of refraction of the glass may be substantially uniform and may be close to that of silica in some embodiments. Possible advantages to such features include reduction of formation of additional waveguides within the core, which becomes increasingly a problem with larger core sizes.

Abstract: An optical fiber amplifier (2) includes: a first pumping source (10); a second pumping source (20); an amplification optical fiber (3) in which an active element is doped; a first optical filter (15) coupled to the first pumping source (10) and one end of the amplification optical fiber (30), the first optical filter (15) transmitting a light at a wavelength the same as the wavelength of a first pumping light and reflecting a light at a wavelength the same as the wavelength of a second pumping light; and a second optical filter (25) coupled to the second pumping source (20) and the other end of the amplification optical fiber (3), the second optical filter (25) transmitting a light at a wavelength the same as the wavelength of the second pumping light and reflecting a light at a wavelength the same as the wavelength of the first pumping light.

Abstract: The invention provides an amplification module for an optical printed circuit board, the optical printed circuit board including 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 including: a pump source including 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 single-mode fiber with certain parameters into the core of another fiber with different parameters; in particular single-mode guided light of a shorter wavelength is coupled into the core of a fiber which is a single-mode fiber at a longer wavelength but acts as multimode fiber for the shorter wavelength. Fabrication involves use of a model to determine a length of a pre-taper.

Abstract: The present disclosure provides an approach to more efficiently amplify signals by matching either the gain materials or the pump profile with the signal profile for a higher-order mode (HOM) signal. By doing so, more efficient energy extraction is achieved.

Abstract: A nanoparticle waveguide apparatus, a nanoparticle waveguide photonic system and a method of photonic transmission employ a nearfield-coupled nanoparticle (NCN) waveguide to cooperatively propagate an optical signal. The nanoparticle waveguide apparatus includes a first optical waveguide adjacent to a second optical waveguide, the first optical waveguide comprising an NCN waveguide having a plurality of nanoparticles. The nanoparticle waveguide photonic system further includes a nearfield coupling (NC) modulator. The method includes providing the NCN waveguides and modulating a coupling between one or both of first and second NCN waveguides and adjacent nanoparticles within one or both of the first and second NCN waveguides.

Abstract: According to some embodiments the optical fiber comprises: (i) a glass core doped with greater than 300 ppm of Er2O3 and at least 0.5 wt % of Al2O3, with a radius R1 from about 3 ?m to about 15 ?m, a relative refractive index delta ?1 from about between 0.3% to 2% relative to the glass cladding; an effective area of LP01 mode between 20 ?m2 and 250 ?m2 at 1550 nm, the glass core radius R1 and refractive index are selected such that the core is capable of supporting the propagation and transmission of an optical signal with X number of LP modes at a wavelength of 1550 nm, wherein X is an integer greater than 1 and not greater than 20; and (ii) a glass cladding surrounding and in direct contact with the glass core.