An optical fiber for a fiber laser includes a core to which a rare-earth element is added, a first cladding formed around the core; and a second cladding formed around the first cladding, and excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light. An addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser.

A photodarkening-resistant ytterbium-doped quartz optical fiber and a method for preparing such a fiber are provided. Glass of a photodarkening-resistant ytterbium-doped quartz optical fiber core rod includes at least Yb.sub.2O.sub.3, Al.sub.2O.sub.3, P.sub.2O.sub.5, SiO.sub.2. The proportions of Yb.sub.2O.sub.3, Al.sub.2O.sub.3, and P.sub.2O.sub.5 in the entire substance are Yb.sub.2O.sub.3: 0.05-0.3 mol %, Al.sub.2O.sub.3: 1-3 mol %, and P.sub.2O.sub.5: 1-5 mol %, respectively. In the preparation method for the photodarkening-resistant ytterbium-doped quartz optical fiber, a sol-gel method and an improved chemical vapor deposition method are combined. By using the molecular-level doping uniformity and the low preparation loss thereof respectively, ytterbium ions, aluminum ions and phosphorus ions are effectively doped in a quartz matrix, thereby effectively solving the problems in the optical fiber of high loss, photodarkening caused by cluster or the like, and a central refractive index dip.

An energy storage capsule for storing energy in the form of photons. The body of the capsule may surround a sealed vacuum environment in which several layers of reactive material are contained, including an inner reflective coating, a first photovoltaic cell, an optical amplification medium, a second photovoltaic cell, and an outer reflective coating, provided in that order. The body of the capsule may also be reflective, for example polished aluminum. Light may be emitted from an LED wafer which may be integrated with the surface of the optical amplification medium, directed at the several layers of reactive material. Some photons may be reflected by the reflective material, storing them within the capsule, while others may be absorbed by the photovoltaic cells, powering the LEDs to transmit more photons. The thermal environment of the energy storage capsule may be maintained such that the LEDs can operate at over 100% efficiency.

An optical material including: a silica host; and a Praseodymium dopant; wherein the Praseodymium atoms are configured to form nanoclusters in the silica host. In addition, the optical material may include an Ytterbium co-dopant. The nanoclusters include Ge, Te, Ta, Lu and/or F, Cl to minimize multi-phonon quenching. Moreover, the nanoclusters may be encapsulated in a low phonon energy shell to minimize energy transfer to the host matrix.

An energy storage capsule for storing energy in the form of photons. The body of the capsule may surround a sealed vacuum environment in which several layers of reactive material are contained, including an inner reflective coating, a first photovoltaic cell, an optical amplification medium, a second photovoltaic cell, and an outer reflective coating, provided in that order. The body of the capsule may also be reflective, for example polished aluminum. Light may be emitted from an LED wafer which may be integrated with the surface of the optical amplification medium, directed at the several layers of reactive material. Some photons may be reflected by the reflective material, storing them within the capsule, while others may be absorbed by the photovoltaic cells, powering the LEDs to transmit more photons. The thermal environment of the energy storage capsule may be maintained such that the LEDs can operate at over 100% efficiency.

Disclosed herein is a method comprising injecting light of a first wavelength .sub.1 into a wavelength division multiplexer; injecting light of a second wavelength .sub.2 into the wavelength division multiplexer; combining the light of the first wavelength .sub.1 and the light of the second wavelength .sub.2 in the wavelength division multiplexer to produce light of a third wavelength .sub.3; and reflecting the light of the third wavelength .sub.3 in a dual-Brillouin peak optical fiber that is in communication with the wavelength divisional multiplexer; wherein the dual-Brillouin peak optical fiber has at least two Brillouin peaks, such that an amplitude A.sub.1 of at least one of said Brillouin peaks is within 50% to 150% of an amplitude A.sub.2 of another Brillouin peak 0.5A.sub.2A.sub.11.5A.sub.2; wherein the dual-Brillouin peak optical fiber generates a Brillouin dynamic grating that reflects an improved back-reflected Brillouin signal of the combined light.

An optical fiber for a fiber laser includes a core to which a rare-earth element is added, a first cladding formed around the core; and a second cladding formed around the first cladding, and excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light. An addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser.

An energy storage capsule for storing energy in the form of photons. The body of the capsule may surround a sealed vacuum environment in which several layers of reactive material are contained, including an inner reflective coating, a first photovoltaic cell, an optical amplification medium, a second photovoltaic cell, and an outer reflective coating, provided in that order. The body of the capsule may also be reflective, for example polished aluminum. Light may be emitted from an LED wafer which may be integrated with the surface of the optical amplification medium, directed at the several layers of reactive material. Some photons may be reflected by the reflective material, storing them within the capsule, while others may be absorbed by the photovoltaic cells, powering the LEDs to transmit more photons. The thermal environment of the energy storage capsule may be maintained such that the LEDs can operate at over 100% efficiency.

An energy storage capsule for storing energy in the form of photons. The body of the capsule may surround a sealed vacuum environment in which several layers of reactive material are contained, including an inner reflective coating, a first photovoltaic cell, an optical amplification medium, a second photovoltaic cell, and an outer reflective coating, provided in that order. The body of the capsule may also be reflective, for example polished aluminum. Light may be emitted from an LED wafer which may be integrated with the surface of the optical amplification medium, directed at the several layers of reactive material. Some photons may be reflected by the reflective material, storing them within the capsule, while others may be absorbed by the photovoltaic cells, powering the LEDs to transmit more photons. The thermal environment of the energy storage capsule may be maintained such that the LEDs can operate at over 100% efficiency.

An energy storage capsule for storing energy in the form of photons. The body of the capsule may surround a sealed vacuum environment in which several layers of reactive material are contained, including an inner reflective coating, a first photovoltaic cell, an optical amplification medium, a second photovoltaic cell, and an outer reflective coating, provided in that order. The body of the capsule may also be reflective, for example polished aluminum. Light may be emitted from an LED wafer which may be integrated with the surface of the optical amplification medium, directed at the several layers of reactive material. Some photons may be reflected by the reflective material, storing them within the capsule, while others may be absorbed by the photovoltaic cells, powering the LEDs to transmit more photons. The thermal environment of the energy storage capsule may be maintained such that the LEDs can operate at over 100% efficiency.