An active LMA optical fiber for mitigating Transverse Mode Instability effects is provided. The core of the fiber includes a center core region having one or more rare-earth center dopants and one or more center co-dopants, and a peripheral core region free of rare-earth dopants and having one or more peripheral dopants. The radial refractive-index profile of the core is generally continuous across a boundary between the center core region and the peripheral core region. The selection and the concentrations and distributions of the rare-earth center dopants, the center co-dopants and the peripheral dopants are such that the temperature coefficient is lower in the peripheral core region than in the center core region.

Methods for synthesizing fibers having nanoparticles therein are provided, as well as preforms and fibers incorporating nanoparticles. The nanoparticles may include one or more rare earth ions selected based on fluorescence at eye-safer wavelengths, surrounded by a low-phonon energy host. Nanoparticles that are not doped with rare earth ions may also be included as a co-dopant to help increase solubility of nanoparticles doped with rare earth ions in the silica matrix. The nanoparticles may be incorporated into a preform, which is then drawn to form fiber. The fibers may beneficially be incorporated into lasers and amplifiers that operate at eye safer wavelengths. Lasers and amplifiers incorporating the fibers may also beneficially exhibit reduced Stimulated Brillouin Scattering.

Provided is a method for producing a crystal fiber which can suppress the occurrence of stress birefringence even while distributing a light emission center so as to concentrate on a cross-sectional middle portion. The method for producing a crystal fiber comprises the steps of: using, as a preform, the crystal fiber comprising a light emission center that volatilizes from a melted portion upon the melting of a crystal, and heating a portion or a plurality of portions of the side of the preform, whereby the portion or the plurality of portions of the preform are melted such that only a given amount of the inside of the portion or the plurality of portions of the preform is not melted, to form the melted portion; and sequentially transferring the melted portion in the longitudinal direction of the preform, and cooling the melted portion, whereby the melted portion is continuously recrystallized to form a recrystallized region.

A laser tool apparatus includes a tool body; a fiber optic cable disposed in the tool body, the fiber optic cable including a laser head that emits a laser beam; a reshape optic disposed coaxially downstream of the fiber optic, the reshape optic reshaping the laser beam emitted from the laser head; and a flexible cable attached to the reshape optic. The flexible cable flexibly orients the laser beam at a desired angle within a borehole.

An optical signal transmitter configured to emit wavelength-distinct optical signals along distinct directions to provide a field scanning effect without requiring moving parts to effectuate the scanning. In one implementation, the optical signal transmitter includes a laser source for generating an optical signal including a set of distinct wavelengths, an optical amplifier configured to amplify the optical signal, a wavelength splitter configured to generate a set of optical signals consisting of distinct wavelengths, respectively, and a set of emission ports for emitting the set of optical signals in different directions. In another implementation, the wavelength splitting occurs at the set of emission ports. In yet another implementation, two stages of wavelength splitting are provided. The optical signal transmitter may be implemented in a LIDAR system for ascertaining information concerning objects-of-interests.

The inventive Device is comprising a laser rangefinder for determining the distance along a laser axis between the device and a target object. The laser rangefinder is comprising a pumping laser and a thulium and/or holmium doped fiber laser with a thulium and/or holmium doped fiber section and two Bragg gratings arranged on both sides of the thulium and/or holmium doped fiber section of the thulium and/or holmium doped fiber laser wherein the thulium and/or holmium doped fiber laser is pumped by the pumping laser and configured to emit laser light with a wavelength in the range of 1900 nm to 2150 nm. The inventive device has an improved applicability.

An amplification fiber which can generate a laser beam in a visible region even when a silica glass is used as a base material of a core of the amplification fiber is realized. An amplification fiber according to an embodiment of the present disclosure includes a core configured to generate a laser beam from an excitation beam in a visible region, and a cladding surrounding the core. The core is composed of a core material including Dy, one or more elements selected from Al, Ge, and P, and a silica glass.

A method and apparatus for a silicon photonics chip and a rare-earth-ion-doped waveguide amplifier chip, wherein the rare-earth ion-doped waveguide amplifier is proximate to and optically coupled to the silicon photonics chip.

An EDFA may include an input photodiode configured to generate a control signal based on an input signal. The EDFA may include a blind stage configured to generate an amplified signal based on the control signal and the input signal. The EDFA may include a non-blind stage configured to generate an output signal based on the amplified signal within the blind stage, the control signal, and a feedback signal. The EDFA may include a filter configured to generate a filtered signal based on the output signal. The EDFA may include an output photodiode configured to generate the feedback signal based on the filtered signal. The EDFA may include an alarm device. A signal within the non-blind stage may be generated based on the feedback signal and the control signal. The alarm device may be configured to generate an alarm signal when the signal exceeds a threshold value.

Mid-infrared-transparent optical fiber products with enhanced resistance to OH diffusion are disclosed, which may be used fiber laser oscillator and amplifiers systems. In one embodiment, an optical fiber product may include optical fiber configured for propagation of mid-infrared radiation toward a light-radiating endface of or coupled to the optical fiber, and a diffusion barrier disposed on the light-radiating endface and configured for allowing the mid-infrared radiation emanating from the light-radiating endface to pass therethrough and for preventing OH diffusion therethrough toward the light-radiating endface. In another embodiment, an optical fiber product may include an optical fiber for propagation of mid-infrared radiation and an endcap coupled to the optical fiber for receiving therefrom the mid-infrared radiation and radiating out the mid-infrared radiation, the endcap being made of an endcap material that has no or a low amount of fluoride and that is less permeable to OH diffusion than the fiber-optic material.