A side grating based light coupling system comprises an optical fiber, a side grating disposed on one side of the lateral wall of the optical fiber, and a laser array disposed adjacent to the other side of the lateral wall of the optical fiber. The side grating comprises a plurality of grating elements arranged in a non-uniform arrangement. The laser array for generating a laser beam towards and passes through the optical fiber, and the laser beam is converted into at least one laser beam through the plurality grating elements. The diffraction efficiencies of the converted laser beams are different. The converted laser beams propagate inside the optical fiber based on total internal reflection. The plurality of grating elements of the side grating are heterogeneous arrangement without loading the optical collimating lens, and can reduce scattering loss by controlling the asymmetric diffraction efficiency, to improve optical coupling efficiency.

Provided are a high-efficiency parallel-beam laser optical fiber drawing method and optical fiber, the method including the steps of: S1: providing base planes on the side surfaces of both a gain optical fiber preform and a pump optical fiber preform, inwardly processing the base plane of the gain optical fiber preform to make a plurality of ribs protrude, and inwardly providing a plurality of grooves on the base plane of the pump optical fiber preform; S2: embedding the ribs into the grooves, tapering and fixing one end of the combination of the ribs and the grooves to form a parallel-beam laser optical fiber preform; S3: drawing the parallel-beam laser optical fiber preform into parallel-beam laser optical fibers. The process has high repeatability, and the obtained parallel-beam laser achieves peelability of pump optical fibers in a set area, thus facilitating multi-point pump light injection of parallel-beam laser optical fibers.

A device for laterally coupling pump light into a fiber. A fiber runs in a longitudinal direction, having an optically active medium to be pumped and a lateral wall running approximately in the longitudinal direction, and at least one light coupler, at least some part of which runs parallel to the fiber along the lateral wall. The light coupler is an optical waveguide which is optically coupled to the fiber such that pump light propagating in the optical waveguide can be coupled into the fiber via the lateral wall. The efficiency of the pump light coupling is improved by a plurality of windings of the fiber being located alternately with waveguides on a substrate. The pump light can be coupled into all waveguides simultaneously, for example by a prism.

A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity.

The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

A homogeneous pump structure of laser, and a design method for the homogeneous pump structure of laser. The homogeneous pump structure of laser is used in a fiber laser or a fiber laser amplifier, and comprises a gain fiber (21). The gain fiber (21) comprises a pump light input end and a pump light output end. The pump area of the gain fiber (21) gradually decreases from the pump light input end to the pump light output end, so that a change rate between a pump light absorption capacity of each of segments, with equal lengths, of the gain fiber (21) and a pump light absorption capacity of a neighboring segment is smaller than b %, b being an empirical value.

A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity.

Apparatus and method for amplifying laser signals using segments of fibers of differing core diameters and/or differing cladding diameters to suppress amplified spontaneous emission and non-linear effects such as four-wave mixing (FWM), self-phase modulation, and stimulated Brillouin and/or Raman scattering (SBS/SRS). In some embodiments, different core sizes have different sideband spacings (spacing between the desired signal and wavelength-shifted lobes). Changing core sizes and providing phase mismatches prevent buildup of non-linear effects. Some embodiments further include a bandpass filter to remove signal other than the desired signal wavelength and/or a time gate to remove signal at times other than during the desired signal pulse. Some embodiments include photonic-crystal cores for the signal and/or photonic-crystal inner cladding for the pump and/or use reflector connector segments. Some embodiments include an inner glass cladding to confine the signal in the core and an outer glass cladding to confine pump light in the inner cladding.

High power parallel fiber arrays for the amplification of high peak power pulses are described. Fiber arrays based on individual fiber amplifiers as well as fiber arrays based on multi-core fibers can be implemented. The optical phase between the individual fiber amplifier elements of the fiber array is measured and controlled using a variety of phase detection and compensation techniques. High power fiber array amplifiers can be used for EUV and X-ray generation as well as pumping of parametric amplifiers.

A fluorescence guide plate includes first and second surfaces, an edge surface connecting a periphery of the first surface with a periphery of the second surface, and a dichroic mirror laminated on the first surface. Fluorescent material is dispersed at least one of inside a space defined by the first surface, the second surface, and the edge surface, on the first surface, or on the second surface. The fluorescence guide plate has a plate-shaped structure made of a material with a higher refractive index than an outside. The fluorescence guide plate is configured such that, when irradiation light enters from the first surface, the fluorescence emitted from the fluorescent material exits from the edge surface. A reflection wavelength band of a normal incident beam reflected by the dichroic mirror lies in a range of wavelengths longer than a peak wavelength of a fluorescence wavelength band of the fluorescent material.