An all-fiber laser oscillator comprises a laser cavity, an amplification fiber, a plurality of diode lasers, and at least one side-pump signal-and-pump combiner (combiner). The combiner comprises a double-clad fiber (DCF) and four or more multimode fibers (MMFs). DCF comprises a first taper portion, whereas each of MMFs comprises a second taper portion fused around DCF. MMFs are configured to carry a portion of combined optical energy (COE) and to couple to DCF. The first taper portion can partially compensate a beam divergence created by the second taper portion, thereby increasing a coupling efficiency of COE coupled from MMFs to DCF with improved thermal performance. In a coupling portion, a refractive index difference between MMFs and DCF is configured to form a backward coupling barrier to suppress an optical energy in DCF from coupling into MMFs, thereby protecting the plurality of diode lasers from damage.

An object of the present disclosure is to implement a clad-excitation rare-earth-added optical fiber amplifier with a high light-to-light conversion efficiency. The present disclosure is an optical fiber amplifier having, in a longitudinal direction of a rare-earth-added optical fiber, a light collection structure that collets an excitation light, which propagates through a clad portion, into a core portion.

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.

A single mode fiber pulsed oscillator includes an all normal dispersion ring cavity provided with a mode-locking fiber loop component and a giant chirp generating fiber component. The mode-locking fiber loop component is configured with a hybrid of NOLM and NALM configurations which is operative to induce a first phase acquisition of a spectrally narrow pulse due to SPM. The giant chirp generating fiber loop component is configured to induce the additional phase acquisition to the pulse broadened in the mode-locking fiber component so as to generate a pulse with a giant chirp. The fiber loop components each include a fiber amplifier and a coil of fiber. The amplifiers each are configured with an active fiber provided with a core which supports multiple transverse mode in a range of wavelength except for the desired wavelength at which the core is configured to support a single fundamental mode.

A laser system according to an embodiment of the present invention includes an oscillation unit to generate a laser output, a connection unit to connect the oscillation unit with an optical fiber loop, an amplifying unit to amplify the laser output on the optical fiber loop, a conversion unit disposed on the optical fiber loop to convert pulsed wave laser output into continuous wave laser output, and an output unit disposed between the connection unit and the conversion unit to split a part of the laser output toward the conversion unit. The system for generating a high output pulsed wave laser and converting the pulsed wave laser into a continuous wave laser may be implemented in a simple structure and small size with high stability and high reproducibility. In addition, a high output laser may be obtained. Also, since conversion from the pulsed wave into the continuous wave is easy, both of the high output pulsed wave and the high output continuous wave may be obtained as necessary.

A multi-core optical amplifying fiber device includes a plurality of multi-core optical amplifying fibers including a plurality of core portions doped with amplification medium and a cladding portion formed at outer peripheries of the plurality of core portions; and a connection portion connecting the core portions of the plurality of multi-core optical amplifying fibers to one another. The connection portion connects the core portions to restrain deviation, between every connected core portions, of amplification gain for a total length of the core portions connected one another.

A 3-dimensional (3-D) inscripted wavelength division multiplexer (WDM) coupler for optical amplifiers is provided. The 3-D WDM coupler includes a substrate. The 3-D WDM coupler further includes a 3-dimensional pump waveguide direct laser inscripted into the substrate. The 3-D WDM coupler also includes a optical pump laser coupled into the 3-dimensional pump waveguide. The 3-D WDM coupler further includes a multicore fiber coupled into cores in the direct laser inscripted substrate.

A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Peak power handling capability of fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive pulse stretching in the presence of self-phase modulation and gain results in the formation of high-power parabolic pulses. To ensure a wide tunability of the whole system, Raman-shifting of the compact sources of ultrashort pulses in conjunction with frequency-conversion in nonlinear optical crystals can be implemented, or an Anti-Stokes fiber in conjunction with fiber amplifiers and Raman-shifters are used. Positive dispersion optical amplifiers are used to improve transmission characteristics. An optical communication system utilizes a Raman amplifier fiber pumped by a train of Raman-shifted, wavelength-tunable pump pulses, to thereby amplify an optical signal which counterpropagates within the Raman amplifier fiber with respect to the pump pulses.

As kilowatt class fiber laser and amplifier systems become more in demand, there are ongoing efforts to improve optical fiber laser and amplifier designs to maximize efficiency and further increase the capacity of these high-energy optical fiber lasers and amplifiers. The present disclosure provides a fiber laser or amplifier system configured to efficiently and conveniently generate and couple high numerical aperture and high-energy pump light into a fiber laser or amplifier system.

In an optical fiber device having a configuration in which an optical fiber is joined to a side surface of another optical fiber, a joint portion is suppressed from reaching a high temperature. The optical fiber device includes a first fluoride fiber, a second fluoride fiber, and a heat dissipation member. The first fluoride fiber guides light. The second fluoride fiber has a first end on or from which light is incident or output and a second end at which an end surface of the second fluoride fiber is obliquely joined to a side surface of the first fluoride fiber.