An integrated, high-performance amplifier subsystem is based on an optimized design of a multimode erbium-doped fiber amplifier (MM-EDFA) and a wavelength- and mode-selective pump coupler (PC). The length and ring doping profile of the MM-EDF and the pump-mode powers can be optimized to obtain low mode-dependent gain (MDG), low noise figure (NF) and high power-conversion efficiency (PCE). The pump coupler can be designed with high pump-mode efficiency and low signal-mode loss by appropriate selection of the pump mode group and the index exponent of an intermediate graded-index (GI) coupling fiber.

According to an embodiment, a crystalline color-conversion device includes an electrically driven first light emitter, for example a blue or ultraviolet LED, for emitting light having a first energy in response to an electrical signal. An inorganic solid single-crystal direct-bandgap second light emitter having a bandgap of a second energy less than the first energy is provided in association with the first light emitter. The second light emitter is electrically isolated from, located in optical association with, and physically connected to the first light emitter so that in response to the electrical signal the first light emitter emits first light that is absorbed by the second light emitter and the second light emitter emits second light having a lower energy than the first energy.

According to an embodiment, a crystalline color-conversion device includes an electrically driven first light emitter, for example a blue or ultraviolet LED, for emitting light having a first energy in response to an electrical signal. An inorganic solid single-crystal direct-bandgap second light emitter having a bandgap of a second energy less than the first energy is provided in association with the first light emitter. The second light emitter is electrically isolated from, located in optical association with, and physically connected to the first light emitter so that in response to the electrical signal the first light emitter emits first light that is absorbed by the second light emitter and the second light emitter emits second light having a lower energy than the first energy.

A solar-pumped laser device includes: a light-guiding plate configured such that a fluorescence substance absorbing solar light and emitting fluorescence including a predetermined wavelength is dispersed in the light-guiding plate so as to bring the fluorescence to exit a predetermined surface; and an optical fiber disposed close to the predetermined surface, the optical fiber including: a core part in which a medium excitable by the fluorescence so as to emit a laser is dispersed; and a clad part that is formed by a material through which the fluorescence passes, is disposed around the core part, and has a smaller refractive index than a refractive index of the core part, wherein a light emitted by the medium is totally reflected by one end surface of the optical fiber, and is brought to pass through the other end surface of the optical fiber.

A solar-pumped laser device includes: a light-guiding plate configured such that a fluorescence substance absorbing solar light and emitting fluorescence including a predetermined wavelength is dispersed in the light-guiding plate so as to bring the fluorescence to exit a predetermined surface; and an optical fiber disposed close to the predetermined surface, the optical fiber including: a core part in which a medium excitable by the fluorescence so as to emit a laser is dispersed; and a clad part that is formed by a material through which the fluorescence passes, is disposed around the core part, and has a smaller refractive index than a refractive index of the core part, wherein a light emitted by the medium is totally reflected by one end surface of the optical fiber, and is brought to pass through the other end surface of the optical fiber.

A Raman laser device including: a Raman lasing medium adapted to undergo Raman lasing; and at least one pumping beam, for pumping a Stokes seed beam by stimulated Raman scattering whilst it traverses the Raman lasing medium.

A Raman laser device including: a Raman lasing medium adapted to undergo Raman lasing; and at least one pumping beam, for pumping a Stokes seed beam by stimulated Raman scattering whilst it traverses the Raman lasing medium.

Provided is a solar-pumped fiber laser device that includes: a first layer of a light guiding material or a fluorescent material having a circular or an elliptical planar contour with an even thickness; and an optical fiber wound around a peripheral thickness edge of the first layer, wherein the optical fiber is irradiated with light formed of solar light having entered a flat surface of the planar contour of the first layer, the solar light being scattered by the light guiding material, or with fluorescence generated by applying the solar light having entered the flat surface of the planar contour of the first layer to the fluorescent material.

Provided is a solar-pumped fiber laser device that includes: a first layer of a light guiding material or a fluorescent material having a circular or an elliptical planar contour with an even thickness; and an optical fiber wound around a peripheral thickness edge of the first layer, wherein the optical fiber is irradiated with light formed of solar light having entered a flat surface of the planar contour of the first layer, the solar light being scattered by the light guiding material, or with fluorescence generated by applying the solar light having entered the flat surface of the planar contour of the first layer to the fluorescent material.

A controllable laser amplifier apparatus includes a gain medium and a seed laser emitter configured to generate a seed laser beam, the seed laser emitter directed toward the gain medium. The apparatus has at least two pump laser emitters configured to generate respective pump laser beams, wherein the pump laser emitters are adjustable such that respective intensities of the pump laser beams are adjustable relative to one another and/or relative to the seed laser pump, wherein the pump laser emitters are arranged such that at least one of the pump laser beams is laterally offset relative to the seed laser beam, and wherein the pump laser beams are configured to effect a gain profile in the gain medium. An output laser beam from the gain medium is a function of at least the gain profile and the seed laser beam.