Abstract: An ultra-high power fiber laser system includes a multimode combiner which is configured with a plurality of low mode fibers bundled together and tapering toward its downstream end. A clad mode absorber extends along the tapered downstream end and over a portion of the combiner's output fiber. The absorber is configured with adjacent zones which are provided with respective refractive indices. In a forward propagating direction of signal, the upstream zone includes polymeric material with the refractive index higher than that of the cladding of the combiner end fiber. The intermediate zone includes polymeric material configured with a refractive index lower than that of the cladding of the combiner output fiber. The downstream zone is configured with polymeric material having a refractive index lower than that of the cladding of the combiner output fiber and impregnated with a plurality of light diffusers.

Abstract: A clad absorber unit is provided on a passive fiber of a high power fiber laser system and operative to trap and remove modes propagating along the waveguide clad of the fiber. The mode absorber is configured with such an optimal length that the clad light may be removed in a localized manner, substantially uniformly removed over the entire length thereof. The absorber removing clad light in a unformed fashion includes a host material impregnated with diffusers.

Abstract: A clad absorber unit is provided on a passive fiber of a high power fiber laser system and operative to trap and remove modes propagating along the waveguide clad of the fiber. The mode absorber is configured with such an optimal length that the clad light may be removed in a localized manner, substantially uniformly removed over the entire length thereof. The absorber removing clad light in a unformed fashion includes a host material impregnated with diffusers.

Abstract: A high power fiber laser system includes a booster winch is configured as a fiber amplifier extending over free space, pump source and laser head including a reflective element which receives pump light and reflects toward the output end of the booster in a counter signal-propagating direction. The booster is configured with concentric and coextending frustoconically shaped (“MM”) core and cladding around the core. The core includes a mode transition region expanding between small diameter SM input and large diameter MM output core ends and configured so that amplification of high order modes is substantially suppressed as a single mode (“SM”) signal light propagates from the input to output core ends. The laser head receives output ends of respective pump light delivery fibers and signal fiber, respectively. The pump source is structured with a plurality of independent sub pumps arranged around the booster.

Abstract: A high power fiber laser system is configured with a combiner end fiber spliced to a combiner output fiber. The system further includes a light stripper extending along the combiner end and output fibers and configured with sequentially located zones which are provided with respective refractive indices. In a forward propagating direction of light signal, the upstream zone includes polymeric material with the refractive index higher than that of the cladding of the combiner end fiber. This zone is configured to remove the backreflected core guided light bled into the cladding of the combiner through a splice between combiner end and output fibers. The intermediate zone includes polymeric material configured with a refractive index lower than that of the cladding of the combiner output fiber so it can prevent clad guided signal light from decoupling the cladding under the material.

Abstract: An ultra-high power fiber laser system includes a multimode combiner which is configured with a plurality of low mode fibers bundled together and tapering toward its downstream end. The system further includes a clad mode absorber extending along the tapered downstream end of the combiner and extending over a portion of the combiner's output fiber. The absorber is configured with sequentially located zones which are provided with respective refractive indices. In a forward propagating direction of light signal, the upstream zone includes polymeric material with the refractive index higher than that of the cladding of the combiner end fiber. This zone is configured to remove the back reflected core guided light bled into the cladding of the combiner through a splice between combiner end and output fibers.

Abstract: A monolithic fiber has a double bottleneck-shaped core configured with opposite uniformly configured end regions, frustoconical transformer regions which run inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The core is configured as a multimode core or single-mode core and capable of guiding a single transverse mode between the end regions without splice losses.

Abstract: A high power single mode fiber laser system has a monolithic active fiber configured with a double bottleneck-shaped multimode (MM) core which is capable of supporting substantially only a fundamental mode at a given wavelength. The core has opposite uniformly configured end regions, frustoconical transformer regions running inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The MM core is configured with a refractive step-index profile which includes a continuous dip configured to shape an intensity field of the fundamental mode from a Gaussian or dome-shaped field profile to a two-peak-shaped profile and back to the Gaussian filed profile.

Abstract: A monolithic fiber has a double bottleneck-shaped core configured with opposite uniformly configured end regions, frustoconical transformer regions which run inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The core is configured as a multimode core or single-mode core and capable of guiding a single transverse mode between the end regions without splice losses.

Abstract: A high power single mode fiber laser system has a monolithic active fiber configured with a double bottleneck-shaped multimode (MM) core which is capable of supporting substantially only a fundamental mode at a given wavelength. The core has opposite uniformly configured end regions, frustoconical transformer regions running inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The MM core is configured with a refractive step-index profile which includes a continuous dip configured to shape an intensity field of the fundamental mode from a Gaussian or dome-shaped field profile to a two-peak-shaped profile and back to the Gaussian filed profile.

Abstract: The present disclosure relates to a modular fiber laser system operative to controllably guide a beam which is launched from a feeding fiber into a process fiber so that the high-aperture component is coupled and guided in cladding of the process fiber, and a low-aperture component is coupled into the core of the fiber. The laser system further has a reflective element configured with light-reflecting and light-transmitting portions. The high-aperture component at least partially decouples from the cladding into the core so that the core radiates the high-aperture and low-aperture components. The high-aperture component is incident upon the light-reflecting portion and backreflected into the process fiber so that a sensor array, which is located between the feeding and process fibers, detects the reflected light.

Abstract: A high power single mode fiber laser system is configured with an active fiber including coextending multimode core (MM) and cladding around the MM core. The MM core is doped with one or more ions selected from rare earth and transitional metals and has a bottleneck cross in accordance with one aspect of the disclosure. The bottleneck cross-section includes a relatively small uniformly dimensioned input end region, a frustoconical region and a relatively large uniformly dimensioned amplifying region. The refractive step index of the MM core is configured with a central dip shaped and dimensioned along the input region so as not to disturb a Gaussian field profile of fundamental mode, gradually transform the Gaussian field profile into the ring profile of the fundamental mode and support the latter along the amplifying region.

Abstract: The present disclosure relates to a modular fiber laser system operative to controllably guide a beam which is launched from a feeding fiber into a process fiber so that the high-aperture component is coupled and guided in cladding of the process fiber, and a low-aperture component is coupled into the core of the fiber. The laser system further has a reflective element configured with light-reflecting and light-transmitting portions. The high-aperture component at least partially decouples from the cladding into the core so that the core radiates the high-aperture and low-aperture components. The high-aperture component is incident upon the light-reflecting portion and backreflected into the process fiber so that a sensor array, which is located between the feeding and process fibers, detects the reflected light.

Abstract: A monolithic fiber is configured with a double bottleneck-shaped multimode (MM) core capable of supporting substantially only a fundamental mode at a given wavelength and having opposite end regions, frustoconically shaped transformer regions, which run inwards from the respective end regions, and a central uniformly dimensioned region, which bridges the transformer regions. The MM core has a refractive step-index profile which is configured with a centrally positioned dip having a variable width along the length of the fiber. The width of the dip is relatively small at the end regions of the MM core so as to support only the fundamental mode with a Gaussian profile. As the dip becomes larger along the input transformer region, it gradually shapes the Gaussian profile into the ring profile of the fundamental mode, which is guided along the central region of the MM core.

Abstract: A powerful fiber laser system is configured with at least one filtering element capable of preventing a backreflected Raman component of the main signal from propagating along the upstream stretch of the system. The filtering element includes a slanted fiber grating, one or more cladding formations disposed in a cladding of fiber and having a refractive index greater than that one of the cladding, but lower than a refractive index of the core, and/or a combination of two spaced apart single mode fibers and a low mode fiber spliced to the opposing ends of the respective SM fibers.

Abstract: A high power single mode fiber laser system is configured with an active fiber including coextending multimode core (MM) and cladding around the MM core. The MM core is doped with one or more ions selected from rare earth and transitional metals and has a bottleneck cross in accordance with one aspect of the disclosure. The bottleneck cross-section includes a relatively small uniformly dimensioned input end region, a frustoconical region and a relatively large uniformly dimensioned amplifying region. The refractive step index of the MM core is configured with a central dip shaped and dimensioned along the input region so as not to disturb a Gaussian field profile of fundamental mode, gradually transform the Gaussian field profile into the ring profile of the fundamental mode and support the latter along the amplifying region.

Abstract: A monolithic fiber is configured with a double bottleneck-shaped multimode (MM) core capable of supporting substantially only a fundamental mode at a given wavelength and having opposite end regions, frustoconically shaped transformer regions, which run inwards from the respective end regions, and a central uniformly dimensioned region, which bridges the transformer regions. The MM core has a refractive step-index profile which is configured with a centrally positioned dip having a variable width along the length of the fiber. The width of the dip is relatively small at the end regions of the MM core so as to support only the fundamental mode with a Gaussian profile. As the dip becomes larger along the input transformer region, it gradually shapes the Gaussian profile into the ring profile of the fundamental mode, which is guided along the central region of the MM core.

Abstract: A dynamic compensator for a fiber optic cable having a jacket which is centered along a longitudinal axis, an elongated buffer tube surrounded by the jacket, and an elongated fiber surrounded by the buffer tube and dimensioned to move radially inwards and outwards within the buffer tube. The dynamic compensator includes a cable holder configured to receive and loop a portion of the fiber optic cable so that when the jacket elongates, the fiber extending along the loop is displaced radially inwards so as to release stresses upon end portions of the fiber, and when the jacket shrinks, the fiber is displaced radially outward to increase stresses upon the end portions of the fiber.

Abstract: A dynamic compensator for a fiber optic cable having a jacket which is centered along a longitudinal axis, an elongated buffer tube surrounded by the jacket, and an elongated fiber surrounded by the buffer tube and dimensioned to move radially inwards and outwards within the buffer tube. The dynamic compensator includes a cable holder configured to receive and loop a portion of the fiber optic cable so that when the jacket elongates, the fiber extending along the loop is displaced radially inwards so as to release stresses upon end portions of the fiber, and when the jacket shrinks, the fiber is displaced radially outward to increase stresses upon the end portions of the fiber.

Abstract: A powerful fiber laser system is configured with at least one large-area multi-clad rare-earth doped fiber, which is configured with a MM core capable of propagating a single mode laser emission at a first wavelength, and with at least one pumping assembly capable of generating an optical pump output at a wavelength shorter than the first wavelength of the rare-earth doped fiber. The pumping assembly has a plurality SM fiber lasers coupled to a SM-MM combiner which is operative to lunch the pump output into the cladding of the rare-earth doped fiber so that the powerful fiber laser system is operative to deliver a power of up to 20 kW.