A light concentrator includes a luminescent concentrator and a gain medium. The luminescent concentrator includes a semiconductor material and the semiconductor material absorbs first photons. The first photons have energy greater than or equal to a threshold energy, and the semiconductor material emits second photons through a spontaneous emission process where the second photons have less energy than the first photons. The gain medium is optically coupled to the luminescent concentrator to receive the second photons. The gain medium absorbs the second photons, and in response to absorbing the second photons, the gain medium emits third photons through a stimulated emission process. The third photons have less energy than the second photons.

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 planar waveguide amplifier includes a planar waveguide including a flat plate-like core; a first cladding provided on a first principal face of the core; and a second cladding provided on a second principal face of the core, and signal light and pumping light travel into the planar waveguide so that the signal light and the pumping light propagate inside the core in such a manner that optical paths of the signal light and the pumping light overlap each other, and in a zig-zag manner, and the core is an amplification medium containing a rare-earth element serving as an active ion of a three-level system, and absorbs the signal light on the basis of a reduction in intensity of the pumping light.

Included are: a first dielectric multilayer film (15) for transmitting a wavelength band including a wavelength of signal light (2) and reflecting first excitation light (4), the first dielectric multilayer film (15) being disposed on one of two end surfaces of a core (11), a first inner cladding (12), a first outer cladding (13), and a second outer cladding (14); and a second dielectric multilayer film (12) for transmitting a wavelength band including the wavelength of the signal light (2) and reflecting the first excitation light (4), the second dielectric multilayer film (12) being disposed on the other one of the two end surfaces.

Disclosed is a terahertz laser device based on phonon vibration excitation, including a resonant cavity composed of a hollow waveguide made of a composite film and optical lenses at both ends of the waveguide, where M represents nano-metal particles. A zinc oxide mesomorphic microsphere is used herein as a source, symmetric stretching vibration of nanosheets on the zinc oxide microsphere is excited and induced by a laser and is transmitted through elastic and electric coupling among the nanosheets, and a terahertz wave with a frequency of 0.36 THz is radiated by means of phonon vibration; moreover, the zinc oxide mesomorphic microspheres and the nano-metal particles are mixed evenly to produce a strong local electric field a few nanometers nearby a surface of the metal particle by taking advantage of a surface-enhanced Raman effect of the nano-metal particles, a nanocantilever of the ZnO mesomorphic microsphere is greatly changed in polarizability with ample contact of the nano-metal particles and the ZnO mesomorphic microspheres, and thus the terahertz radiation power thereof is enhanced.

Included are: a first dielectric multilayer film (15) for transmitting a wavelength band including a wavelength of signal light (2) and reflecting first excitation light (4), the first dielectric multilayer film (15) being disposed on one of two end surfaces of a core (11), a first inner cladding (12), a first outer cladding (13), and a second outer cladding (14); and a second dielectric multilayer film (12) for transmitting a wavelength band including the wavelength of the signal light (2) and reflecting the first excitation light (4), the second dielectric multilayer film (12) being disposed on the other one of the two end surfaces.

A method of emitting photons at a desired wavelength, including: providing a material having a first region of high absorption of radiation at a first set of wavelength of radiation, contiguous with a second region of low absorption of radiation at a shorter set of wavelengths, and a third region of high emission at a further shorter set of wavelengths; applying energy to the material at the first region, such that most of an effective black body radiation of said material at a temperature of the material would fall within the second region and be configured to transfer energy to said third region and not overlap with the first region; and emitting energy from the material at the third region, powered by said applying energy.

A method of emitting photons at a desired wavelength, including: providing a material having a first region of high absorption of radiation at a first set of wavelength of radiation, contiguous with a second region of low absorption of radiation at a shorter set of wavelengths, and a third region of high emission at a further shorter set of wavelengths; applying energy to the material at the first region, such that most of an effective black body radiation of said material at a temperature of the material would fall within the second region and be configured to transfer energy to said third region and not overlap with the first region; and emitting energy from the material at the third region, powered by said applying energy.

A manufacturing technique of ultra-wideband high gain optical fibers and devices is disclosed, including: (1) manufacturing a gain fiber, which is a composite structural optical fiber, having a core composed of a plurality of sets of sector structures distributed symmetrically or a plurality of concentric ring structures. The core is composed of at least two kinds of rare-earth-ion-doped glass, and luminescence centers are located in different sector or ring structure regions; and (2) constructing a fiber laser: using the gain fiber, selectively exciting rare earth ions in different regions in the core by controlling a shape of pump light spot, and combining with fiber grating pairs to realize a tunable laser output. The present disclosure can manufacture gain fibers with high-gain and ultra-wideband characteristics by combining the design of the fiber structure and the control of the light field of the pump light.

A device may include an active material, a primary optical system, and a pump optical system. The primary optical system forms a primary folded optical path through the active material for a primary optical beam. The pump optical system forms a pump folded optical path through the active material for pump light. The pump folded optical path overlaps with the primary folded optical path in the active material. The pump light propagating along the pump folded optical path pumps the active material to amplify the primary optical beam propagating through the active material along the primary folded optical path.