Some embodiments may include a fiber laser including two or more input fibers and an output fiber to deliver a beam to a workpiece, the fiber laser comprising. The fiber laser may include a combiner having ends and a length, wherein the combiner is arranged to release, from its length, a portion of back-reflected light received from the output fiber at an output end of the ends from the combiner, the combiner including: a capillary tube to enclose part of the two or more input fibers at an input end of the ends of the combiner, the capillary tube having ends and a length located between the ends of the capillary tube; and a cladding light stripper (CLS) defined by part of the length of the capillary tube, wherein the CLS provides the release of the portion of the back-reflected light. Other embodiments may be disclosed and/or claimed.

A fiber laser system based in solitonic passive mode-locking, including a laser diode to emit and deliver an optical signal of a first wavelength; a single-fiber laser cavity including a dichroic mirror, a SESAM and a polarization maintaining highly-doped active fiber, to receive the emitted signal and to emit a pulsed optical signal of a second wavelength, generating laser light in the form of mode-locked ultrashort pulses; a unit coupling the laser diode to the single-fiber laser cavity; and an isolator device protecting the cavity from back reflections. The solitonic mode-locked ultrashort pulses are comprised in a range of 100 fs<10 ps with repetition rates of hundreds MHz to tens of GHz.

A light-emitting device includes an optical fiber, a first light source unit, and a second light source unit. The optical fiber includes a wavelength converting portion. The wavelength converting portion is provided between a light incident portion and a light emerging portion. The wavelength converting portion contains a wavelength converting material. The wavelength converting material is excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light and amplifies the spontaneous emission of light to produce an amplified spontaneous emission of light. The first light source unit makes the excitation light incident on the light incident portion. The second light source unit makes seed light, causing a stimulated emission of light to be produced from the wavelength converting material that has been excited by either the excitation light or the amplified spontaneous emission of light, incident on the light incident portion.

A fiber laser system based in solitonic passive mode-locking, including a laser diode to emit and deliver an optical signal of a first wavelength; a single-fiber laser cavity including a dichroic mirror, a SESAM and a polarization maintaining highly-doped active fiber, to receive the emitted signal and to emit a pulsed optical signal of a second wavelength, generating laser light in the form of mode-locked ultrashort pulses; a unit coupling the laser diode to the single-fiber laser cavity; and an isolator device protecting the cavity from back reflections. The solitonic mode-locked ultrashort pulses are comprised in a range of 100 fs<10 ps with repetition rates of hundreds MHz to tens of GHz.

An optical system allows sharing of optical components and seed and pump light to achieve desired optical amplification in laser light while reducing the number of optical components and complexity of the overall optical system and achieving improved performance in lasers and reduced cost in fabrication and final lasers for large scale production of such lasers. Different optical gain sections can be used to allow for sharing of seed and pump light and sharing of optical components while providing multi-stage optical amplification.

A laser assembly comprising a multi-clad fiber optically coupled to a light source configured to emit optical radiation at a first wavelength and a protective element disposed between the light source and the multi-clad fiber so as to prevent a portion of backward-propagating optical radiation at a second wavelength from coupling into the light source.

Disclosed herein is an all-fiber, easy to use, wavelength tunable, ultrafast laser based on soliton self-frequency-shifting in an Er-doped polarization-maintaining very large mode area (PM VLMA) fiber. The ultrafast laser system may include an all polarization-maintaining (PM) fiber mode-locked seed laser with a pre-amplifier; a Raman laser including a cascaded Raman resonator and an ytterbium (Yb) fiber laser cavity; an amplifier core-pumped by the Raman laser, the amplifier including an erbium (Er) doped polarization maintaining very large mode area (PM Er VLMA) optical fiber and a passive PM VLMA fiber following the PM Er VLMA, the passive PM VLMA for supporting a spectral shift to a longer wavelength.

A tunable external cavity laser with dual gain chips, including: a polarization beam splitter having a beam splitting surface arranged at an angle of 45° with respect to a first direction and a second direction perpendicular to the first direction; a first gain chip arranged in the first direction; a second gain chip arranged in the second direction; a feedback cavity arranged in the first direction, wherein the feedback cavity and the first gain chip are respectively arranged on two opposite sides of the polarization beam splitter, and the feedback cavity includes at least one independent Fabry-Perot etalon, at least one air gap Fabry-Perot cavity and a mirror that are arranged in the first direction. The polarization beam splitter and the two gain chips cooperate to share the feedback cavity, so that a wavelength and a phase may be adjusted, and a larger tuning range may be obtained.

An optical connection structure includes a first spatial multiplex transmission line, a second spatial multiplex transmission line, a first lens arrangement, a second lens arrangement and a first beam diameter conversion portion. The first spatial multiplex transmission line has a plurality of first transmission lines. The second spatial multiplex transmission line has a plurality of second transmission lines. The first lens arrangement is optically coupled with the first spatial multiplex transmission line. The second lens arrangement is optically coupled with the second spatial multiplex transmission line. The first beam diameter conversion portion has a first end face and a second end face and arranged between the first spatial multiplex transmission line and the first lens arrangement. The first beam diameter conversion portion is configured such that an optical diameter at the second end face is larger than an optical diameter at the first end face.

Multi-stage fiber amplifiers can amplify signals from a few Watts to several kilowatts. These amplifiers are limited in power by intensity instabilities resulting from a sequence of nonlinear optical effects. These nonlinear optical effects include stimulated Brillouin scattering (SBS), with produces a high-intensity pulse close to the signal wavelength that propagates backward up the amplifier chain, causing permanent damage to the upstream components. This SBS pulse can be blocked by an optical isolator that blocks backward-propagating light at or near the signal wavelength. At high enough power levels, the SBS pulse can also induce backward-propagating light at wavelengths tens to hundreds of nanometers away from the signal wavelength. This SBS-Pulse Induced Non-linear Spectrum light is outside the isolator's reject band, so it can propagate upstream and de-stabilize the upstream amplifier stages. It can be suppressed using a filter with a broad reject band and a suppression ratio of ≥30 dB, enabling higher power operation.