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: 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: A high power fiber laser is configured with a multimode active fiber and input and output single mode passive fibers butt-spliced to respective opposite ends of the active fiber. If the input passive and active fibers do not have substantially matched diameters, a SM radiation coupled into the active fiber may excite fundamental and high order modes which, while interfering with one another, create a non-uniform distribution of refractive index in each of forward and backward light propagation directions along the resonator of the laser. The variable longitudinal perturbation components of the refractive index in respective forward and backward directions along an optical path in the active fiber are distributed in accordance with respective cosine functions.

Abstract: A high power fiber laser is configured with a multimode active fiber and input and output single mode passive fibers butt-spliced to respective opposite ends of the active fiber. If the input passive and active fibers do not have substantially matched diameters, a SM radiation coupled into the active fiber may excite fundamental and high order modes which, while interfering with one another, create a non-uniform distribution of refractive index in each of forward and backward light propagation directions along the resonator of the laser. The variable longitudinal perturbation components of the refractive index in respective forward and backward directions along an optical path in the active fiber are distributed in accordance with respective cosine functions.

Abstract: Optical fiber apparatus having a wavelength of operation, that comprises an optical fiber including a core comprising an active material for providing light having the operating wavelength responsive to the optical apparatus receiving pump optical energy having a pump wavelength; a cladding disposed about the core; at least one region spaced from the core; and wherein the optical fiber is configured and arranged such that at the wavelength of operation the optical fiber can propagate a plurality of modes and wherein the optical fiber comprises a fundamental mode that is primarily a mode of the core and at least one higher order mode (HOM) that is a mixed mode of a selected mode of the core and of a selected mode of the at least one region.

Abstract: Optical apparatus, comprising an optical fiber having a wavelength of operation, the optical fiber comprising an inner core, the inner core supporting a fundamental mode and at least first and second higher order modes (HOMs) at the wavelength of operation; a first ring-shaped core region spaced from and disposed about the inner core; a second ring-shaped core region spaced from and disposed about the ring-shaped core region; and wherein the optical fiber is configured and arranged such that the first HOM optically interacts with the first ring-shaped core region and the second HOM optically interacts with the second ring-shaped core region.

Abstract: An optical fiber apparatus having a wavelength of operation comprises an optical fiber comprising a core; a pump cladding disposed about the core for receiving pump optical energy having a pump wavelength; and a second cladding disposed about for tending to confine pump optical energy to the pump cladding. The core can comprise a rare earth material for providing optical energy having the wavelength of operation responsive to the optical fiber receiving the pump optical energy, and the fiber can further comprise at least one ring core spaced from the core, the ring core defined by inner and outer diameters and comprising the cross sectional area therebetween. The ring core can comprise an absorbing material for absorbing optical energy having the wavelength of operation.

Abstract: Optical apparatus, comprising an optical fiber having a wavelength of operation, the optical fiber comprising an inner core, the inner core supporting a fundamental mode and at least first and second higher order modes (HOMs) at the wavelength of operation; a first ring-shaped core region spaced from and disposed about the inner core; a second ring-shaped core region spaced from and disposed about the ring-shaped core region; and wherein the optical fiber is configured and arranged such that the first HOM optically interacts with the first ring-shaped core region and the second HOM optically interacts with the second ring-shaped core region.

Abstract: An optical fiber apparatus having a wavelength of operatic comprises an optical fiber comprising a core; a pump cladding disposed about the core for receiving pump optical energy having a pump wavelength; and a second cladding disposed about for tending to confine pump optical energy to the pump cladding. The core can comprise a rare earth material for providing optical energy having the wavelength of operation responsive to the optical fiber receiving the pump optical energy, and the fiber can further comprise at least one ring core spaced from the core, the ring core defined by inner and outer diameters and comprising the cross sectional area therebetween. The ring core can comprise an absorbing material for absorbing optical energy having the wavelength of operation.

Abstract: Optical fiber apparatus having a wavelength of operation, that comprises an optical fiber including a core comprising an active material for providing light having the operating wavelength responsive to the optical apparatus receiving pump optical energy having a pump wavelength; a cladding disposed about the core; at least one region spaced from the core; and wherein the optical fiber is configured and arranged such that at the wavelength of operation the optical fiber can propagate a plurality of modes and wherein the optical fiber comprises a fundamental mode that is primarily a mode of the core and at least one higher order mode (HOM) that is a mixed mode of a selected mode of the core and of a selected mode of the at least one region.

Abstract: A laser system includes a multimode fiber (MMF) having a permanent perturbation region which is provided at the predetermined distance from the upstream end of the MMF. The perturbation region is configured so that propagating fundamental and at least one high-order mode (HOM) originated upstream from the perturbation region are split into multiple HOMs which are substantially in counterphase. Hence, the HOMs destructively interfere with and substantially cancel one another.

Abstract: A laser system includes a multimode fiber (MMF) having a permanent perturbation region which is provided at the predetermined distance from the upstream end of the MMF. The perturbation region is configured so that propagating fundamental and at least one high-order mode (HOM) originated upstream from the perturbation region are split into multiple HOMs which are substantially in counterphase. Hence, the HOMs destructively interfere with and substantially cancel one another.

Abstract: A laser system includes a multimode fiber (MMF) receiving a single-mode input beam and a mechanical oscillator coupled to the MMF. The oscillator is operative to modulate a phase of interference wave by periodically extending the fiber total length at such a frequency that a cross-coupling coefficient between fundamental and at least one high-order modes is substantially minimized.