An object of the present disclosure is to allow gain compensation with a simple configuration without adding a new device to the outside. The present disclosure discloses a rare earth doped fiber including a core doped with a rare earth and a cladding region around the core, wherein one or more cavities are provided inside the core, and at least one of the cavities are provided along a longitudinal direction of the rare earth doped fiber.

A laser medium unit 10 in a laser beam amplification device includes a plurality of laser media 14. A cooling medium flow path F1 is provided around the laser medium unit 10 to cool the laser medium unit 10 from outside. A sealed space between the laser media 14 is filled with gas or liquid, and a laser beam for passing through the sealed space is not interfered by a cooling medium flowing outside. Therefore, a fluctuation of an amplified laser beam is prevented, and a quality such as stability and focusing characteristics of the laser beam is improved.

The concentration of substance in blood is measured non-invasively, with high accuracy and with simple configuration. Laser light 100 generated by a light source 10 is locally irradiated on the body epithelium F of a subject, and the resulting diffused reflected light 200 is detected by a light detector 40. The laser light 100 has a wavelength of 9.26 μm. The laser light 100 is generated by converting and amplifying pulsed excitation light 101 from an excitation light source 11 to a long wavelength. A plate-shaped window 300 that is transparent to mid-infrared light is brought in close contact with the body epithelium F. The glucose concentration in interstitial fluid can be calculated using normalized light intensity calculated from a signal ratio of signals from a monitoring light detector 16 and light detector 40.

Structures described herein may include mechanically bonded interlayers for formation between a first Group III-V semiconductor layer and a second semiconductor layer. The mechanically bonded interlayers provide reduced lattice strain by strain balancing between the Group III-V semiconductor layer and the second semiconductor layer, which may be silicon.

A light-emitting device includes an optical amplifier and gives off output light from optical amplifier by making a plurality of seed light rays, having mutually different wavelengths, incident on optical amplifier. Optical amplifier includes a medium portion containing a wavelength-converting element. Optical amplifier has wavelength-converting element thereof excited by excitation light to produce a plurality of partially coherent light rays, of which wavelengths are respectively the same as the mutually different wavelengths of plurality of seed light rays, thereby giving off, as output light, a multi-wavelength light beam. Excitation light has a shorter wavelength than any of plurality of seed light rays and is incident on the medium portion. Multi-wavelength light beam includes a plurality of light rays amplified. Plurality of light rays amplified have wavelengths, which are respectively the same as mutually different wavelengths of plurality of seed light rays.

An optical amplifier includes one or more rare earth element-doped optical fibers each including one or more cores, two or more excitation light sources per single core of the one or more rare earth element-doped optical fibers, configured to emit excitation light for exciting a rare earth element added to the one or more rare earth element-doped optical fibers according to a driving current, and a synthesizing part configured to synthesize the excitation light emitted from the two or more excitation light sources per single core. Two or more cores are provided in total, and the excitation light emitted from the two or more excitation light sources per single core is synthesized and input with respect to each core.

A laser system includes a laser diode that, upon activation, selectively produces a continuous wave of laser light or uniformly spaced, intermittent pulses of laser light. The system further includes a laser focuser with a plurality of lenses that focus the laser light produces by the laser diode and direct the laser light to an optical resonator. The optical resonator includes a lasing medium that, when intersected by the laser light from the laser diode, produces a beam of laser light with a wavelength that may be used for therapeutic treatment. The system is operable to produce the therapeutic laser light when the laser diode is operating in either the continuous wave mode or the pulsed mode, without moving components of the system relative to one another.

A rare earth-doped optical fiber comprises a fluorosilicate core surrounded by a silica cladding, where the fluorosilicate core comprises an alkaline-earth fluoro-alumino-silicate glass, such as a strontium fluoro-alumino-silicate glass. The rare earth-doped optical fiber may be useful as a high-power fiber laser and/or fiber amplifier. A method of making a rare earth-doped optical fiber comprises: inserting a powder mixture comprising YbF.sub.3, SrF.sub.2, and Al.sub.2O.sub.3 into a silica tube; after inserting the powder mixture, heating the silica tube to a temperature of at least about 2000° C., some or all of the powder mixture undergoing melting; drawing the silica tube to obtain a reduced-diameter fiber; and cooling the reduced-diameter fiber. Thus, a rare earth-doped optical fiber comprising a fluorosilicate core surrounded by a silica cladding is formed.

Chip technology for fabricating ultra-low-noise, high-stability optical devices for use in an optical atomic clock system. The proposed chip technology uses diamond material to form stabilized lasers, frequency references, and passive laser cavity structures. By utilizing the exceptional thermal conductivity of diamond and other optical and dielectric properties, a specific temperature range of operation is proposed that allows significant reduction of the total energy required to generate and maintain an ultra-stable laser. In each configuration, the diamond-based chip is cooled by a cryogenic cooler containing liquid nitrogen.

An optical arrangement for adjusting the wavelength of light, comprising: a first light source arranged to generate a first beam of light at a first wavelength; a second light source arranged to generate seed light at a second wavelength; a first Raman shifting medium arranged to receive the light from the first light source in combination with the seed light from the second light source, and to produce, by stimulated Raman scattering, output light at the second wavelength and having temporal properties determined by those of the first beam of light; a third light source arranged to generate seed light at a third wavelength; and a second Raman shifting medium arranged to receive the output light from the first Raman shifting medium in combination with the seed light from the third light source, and to produce, by stimulated Raman scattering, output light at the third wavelength and having temporal properties determined by those of the output light from the first Raman shifting medium; wherein the third wavelength is greater than the second wavelength, and the second wavelength is greater than the first wavelength; wherein the frequency difference between the first beam of light and the seed light from the second light source is a frequency difference where the first Raman shifting medium exhibits Raman gain; and wherein the frequency difference between the output light from the first Raman shifting medium and the seed light from the third light source is a frequency difference where the second Raman shifting medium exhibits Raman gain. Also provided is a corresponding method of adjusting the wavelength of light.