Abstract: Disclosed are multi-stage optical amplifiers that propagate higher-order mode (HOM) signals. One embodiment, among others, comprises a first segment of optical fiber in which a first HOM signal propagates, a second segment of optical fiber in which a second HOM signal propagates, and a mode converter that converts the first HOM signal into the second HOM signal.

Abstract: An optical transmission fiber is formed to include a relatively low-index, relatively thin outer cladding layer disposed underneath the protective polymer outer coating. Stray light propagating along an inner cladding layer(s) within the fiber will be refracted into the thin outer cladding (by proper selection of refractive index values). The thin dimension of the outer cladding layer allows for the stray light to “leak” into the outer coating in a controlled, gradual manner so as to minimize heating of the coating associated with the presence of stray light. The inventive fiber may also be bent to assist in the movement of stray light into the coating.

Abstract: In a LMA optical fiber the index of the core region is graded (i.e., as viewed in a radial cross-section) and has a grading depth of ?ng, as measured from a central maximum at or near the axis to a lower level that is not greater than the central maximum and not less than the index of the cladding region. When the fiber is to be bent at a bend radius, the grading depth, the radius of the core region, and the difference between the central maximum index and the cladding region index are configured to reduce bend distortion. They may also advantageously be configured to maximize the effective mode-field area of the fundamental mode, suppress higher order modes, and reduce bend loss. In a preferred embodiment, the core region includes a centralized gain region, which in turn includes a dark region that is no more than 30% of the area of the gain region. Also described is a method of making such LMA fibers.

Abstract: An apparatus and method for cleaving an optical fiber. The method includes supporting a connector in a fixed axial position along an axis of an optical fiber extending from an end of the connector, and placing an axial tension along the axis of the optical fiber. A fiber engaging member is moved along an arcuate path such that a sharpened blade tip of the fiber engaging member cuts across a cut location of the optical fiber. The axial tension induces crack propagation through the thickness of the optical fiber at the cut location.

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 mode conversion technique to convert higher-order-mode into a nearly fundamental Gaussian shape by using a beam expander is developed and is particularly useful in high-power lasers and amplifiers. By using a beam expander between a transmitted fiber and a conventional mode conversion system, the strict lateral tolerance requirement can be overcome with high conversion efficiency.

Abstract: Disclosed are multi-stage optical amplifiers that propagate higher-order mode (HOM) signals. One embodiment, among others, comprises a first segment of optical fiber in which a first HOM signal propagates, a second segment of optical fiber in which a second HOM signal propagates, and a mode converter that converts the first HOM signal into the second HOM signal.

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: 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: When transmitting in higher-order modes (HOMs), the chances of dielectric breakdown in the bulk glass can be reduced by judicious selection of the mode of transmission. Since energy distributions in the HOM profile change with the mode order, one can calculate the peak intensity for any given HOM. Correspondingly, one can calculate whether any portion of the transmitted pulse will exceed the breakdown threshold for the optical fiber through which the HOM signal is being transmitted. Should the calculated energy exceed the dielectric breakdown threshold, another HOM with a lower peak intensity can be selected for signal transmission. Disclosed are systems and methods for selecting an appropriate HOM to reduce the likelihood of dielectric breakdown.

Abstract: A stretcher fiber includes a core region, inner trench region, ring region, outer trench region, and outer cladding region. The core region has a radius r1, a refractive index n1, and a positive effective refractive index ?n1 with respect to an outer cladding region having an outer radius r0 and a refractive index no, where ?n0 is equal to n1?n0. The inner trench region surrounds the core region and has an outer radius r2, a refractive index n2 less than n0, and a negative effective refractive index ?n2 equal to n2?n0. The ring region surrounds the trench region and has an outer radius r3, a refractive index n3 greater than n0, and a positive effective refractive index ?n3 equal to n3?n0. The outer trench region surrounds the ring region and has an outer radius r4, a refractive index n4 less than n0, and a negative effective refractive index ?n4 equal to n4?n0. The outer cladding region surrounds the outer trench region.

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 fiber laser having at least one pair of reflectors coupled to an optical fiber, the at least one pair of reflectors defining an optical cavity between the at least one pair of reflectors and being configured to reflect light within the optical cavity. At least one light pump is coupled to the optical fiber and configured to provide pump light into the optical cavity, and at least one medium is positioned within the optical cavity and configured to generate signal light from the pump light in the optical cavity. Further, at least one grating positioned within the optical cavity and configured to couple the signal light out of the optical cavity.

Abstract: A technique is described for generating a cylindrically polarized beam, e.g., a radially or azimuthally polarized beam. An input optical fiber is provided that supports signal propagation in a fundamental LP01 mode. A mode converter device converts the fundamental LP01 mode into a higher-order LP11 mode output that includes a linear combination of modes, including cylindrically polarized TM01 and TE01 modes and mixed HE21 (even) and HE21 (odd) modes. The LP11 mode output propagates through a connected phase-engineered fiber having a refractive index profile that includes a steep refractive index step proximate to a peak amplitude of a mode intensity profile of the LP11 mode, such that at least one cylindrically polarized mode has an effective refractive index that is sufficiently separated from those of the mixed modes to allow for coupling to the at least one cylindrically polarized mode with minimal cross-coupling.

Abstract: In a method and system for providing dispersion compensation in an optical system, there is coupled into the optical system at least one pathway into which there is connected a tunable chirped fiber Bragg grating, each such grating providing a respective tunable amount of dispersion. At least one respective DGD element is connected into the respective pathway for each such grating. The set of all such respective DGD elements in a given pathway introduces a bias differential group delay DGD(bias) having an absolute value that, for at least one tuning value of the grating, is substantially equal to differential group delay introduced by the grating.

Abstract: A method of producing an optical amplifying assembly includes providing an amplifying fiber and selecting a first portion and a second portion of the amplifying fiber such that a bend of substantially the same radius and length would cause greater distortion impairments in the first portion than in the second portion. The method further includes coiling the second portion and arranging the first portion to mitigate the impairments due to bend distortion.

Abstract: An electromagnetic device, including: a microfiber or other optical waveguide configured to guide an electromagnetic field output by an electromagnetic field source, the microfiber or other optical waveguide having a diameter that is less than or on an order of a wavelength of the electromagnetic field output by the electromagnetic field source; and a first optical material in contact with the microfiber or other optical waveguide, wherein at least a contact region of the microfiber or other optical waveguide and the first optical material is immersed in a liquid or cured dielectric that has an index of refraction less than the index of refraction of the microfiber or other optical waveguide.

Abstract: Disclosed are optical fiber devices incorporating optical fibers with total dispersion greater than material dispersion, and with preferred dispersion values less than +50 ps/nm-km. The desired dispersion values are obtained when light resides substantially in a single higher order mode (HOM) of the fiber, typically the LP02 mode. The optical fibers also preferably have substantial separation between the effective indices of the HOM and any other mode.

Abstract: A technique is described for creating a localized modulation of an optical fiber's refractive index profile. A segment of optical fiber is loaded into a heating unit having a resistive heating element with a localized heating zone. A selected portion of the fiber segment is positioned within the heating zone, and the heating unit is used to create a refractive index modulation the selected fiber portion. The localized modulation is repeated along the length of the fiber segment to write a fiber grating. Also described is a resistive heating system for performing the described technique.

Abstract: The specification describes an optical fiber device wherein a LOM is converted to an HOM prior to entering the gain section. The gain section is a few mode fiber that supports the HOM. The output from the gain section, i.e. the HOM, may be utilized as is, or converted back to the LOM. With suitable design of the few mode fiber in the gain section of the device, the effective area, Aeff, may be greater than 1600 ?m2. The large mode separation in the gain section reduces mode coupling, allowing greater design freedom and reducing the bend sensitivity of the optical fiber.