A fiber laser amplifier system including a first dual-clad delivery fiber receiving a signal beam and a pump beam, a doped amplifying fiber coupled to the first delivery fiber and receiving the signal beam and the pump beam, and amplifying the signal beam using the pump beam, and a second dual-clad delivery fiber coupled to the amplifying fiber and receiving the amplified signal beam and the pump beam. The system also includes an endcap having an input facet and an output facet. The input facet is coupled to the second delivery fiber and receives the amplified signal beam and the pump beam, and the output facet is configured to pass the amplified signal beam and reflect the pump beam back onto the second delivery fiber to be directed back to the doped amplifying fiber.

A fiber laser system includes: an array of gain fibers configured to transmit signal light; and an array of tapered end caps configured to receive the signal light and output the signal light, wherein each gain fiber in the array of gain fibers is spliced to a respective tapered end cap of the array of tapered end caps. A counter-pumping light source is configured to output counter-pumping light. A dichroic mirror is configured to receive the counter-pumping light and the signal light from the array of tapered end caps. The dichroic mirror is further configured to either allow the counter-pumping light received by the dichroic mirror to pass through the dichroic mirror and reflect the signal light received by the dichroic mirror or allow the signal light received by the dichroic mirror to pass through the dichroic mirror and reflect the counter-pumping light received by the dichroic mirror.

A single mode fiber pulsed oscillator includes an all normal dispersion ring cavity provided with a mode-locking fiber loop component and a giant chirp generating fiber component. The mode-locking fiber loop component is configured with a hybrid of NOLM and NALM configurations which is operative to induce a first phase acquisition of a spectrally narrow pulse due to SPM. The giant chirp generating fiber loop component is configured to induce the additional phase acquisition to the pulse broadened in the mode-locking fiber component so as to generate a pulse with a giant chirp. The fiber loop components each include a fiber amplifier and a coil of fiber. The amplifiers each are configured with an active fiber provided with a core which supports multiple transverse mode in a range of wavelength except for the desired wavelength at which the core is configured to support a single fundamental mode.

Provided is an optical coupler configured to cause an NA of light, which exits a taper fiber, to be smaller as compared with a conventional optical coupler. A taper fiber has a high refractive index part which is provided inside a core of the taper fiber and which has a refractive index smaller than a refractive index n.sub.core of the core. An exit end surface of each GI fiber is bonded to an entrance end surface of the taper fiber so that at least a part of the exit end surface of the each GI fiber overlaps with a section of the high refractive index part. A relative refractive index difference of the taper fiber is smaller than 0.076%.

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 and a tapered output section which tapers from a first diameter to a second diameter that is smaller than the first diameter.

Tapered core fibers are produced using tapered core rods that can be etched or ground so that a fiber cladding has a constant diameter. The tapered core can be an actively doped core, or a passive core. One or more sleeving tubes can be collapsed onto a tapered core rod and exterior portions of the collapsed sleeving tubes can be ground to provide a constant cladding diameter in a fiber drawn from the preform.

A fiber support assembly includes: a first glass tube, wherein the first glass tube is at tached to a microlens or lenslet of a microlens or lenslet array; a second glass tube at least partially disposed within the first glass tube; and a gain fiber disposed within the second glass tube, wherein the gain fiber has a first tapered end cap, and wherein the gain fiber with the first tapered end cap is aligned to the microlens or lenslet attached to the first glass tube. The fiber support assembly may further include: a pump fiber disposed within the second glass tube, wherein the pump fiber has a second tapered end cap; and a reflector configured to receive counter-pumping light from the pump fiber and direct the counter-pumping light to the first tapered end cap of the gain fiber.

A fiber optic assembly includes: a gain fiber configured to output signal light; a first taper configured to expand the signal light output by the gain fiber; and a reversing prism configured to receive counter-pumping light and output the counter-pumping light into the first taper. The first taper is further configured to direct the counter-pumping light towards the gain fiber.

A capillary combiner housing for an optical fiber combiner has an inner combiner casing supporting optical fibers. The capillary combiner housing includes a non-metallic body defining a lumen between an input side and an output side, the lumen sized to receive the inner combiner casing, the non-metallic body having a coefficient of thermal expansion substantially matching that of the inner combiner casing. Also included is a first aperture in the input side, the first aperture having a first inside diameter sized to receive multiple input optical fibers, and a second aperture in the output side, the second aperture having a second inside diameter sized to receive an output fiber.

A mounting surface defines a branching channel, the branching channel having a main channel and one or more sub-channels branching off the main channel. An optic fiber is affixed to the mounting surface, the optic fiber including a cladding layer and an interior surrounded by the cladding layer, wherein part of the optic fiber is suspended over the main channel. A clad light stripper includes one or more discontinuities in an outer surface of the cladding layer of a suspended section of the optic fiber, the one or more outer surface discontinuities to release a portion of the process light. The one or more subchannels include a first sub-channel having an ingress located to capture released light from an individual one of the one or more discontinuities and trap at least a portion thereof.