Supermode lasing and light amplification in multicore bismuth-doped fiber.

Multicore fibers are promising structures with specific light propagation properties, which can be managed to benefit several applications in optical communications, fiber lasers and amplifiers, high-resolution imaging, and fiber-based sensors. The current use of multicore fibers in laser technology is mainly focused on in-phase coherent beam combining in far-field regions (out-cavity) using bulk optical elements. However, this approach is challenging in terms of the power scalability of all-fiber lasers (intra-cavity), particularly with using low-gain media, where it is needed to provide mode-coupling (supermode propagation) stability along relatively long lengths.

Soluble Fluorinated Cardo Copolyimide as an Effective Additive to Photopolymerizable Compositions Based on Di(meth)acrylates: Application for Highly Thermostable Primary Protective Coating of Silica Optical Fiber.

The development of photocurable compositions is in high demand for the manufacture of functional materials for electronics, optics, medicine, energy, etc. The properties of the final photo-cured material are primarily determined by the initial mixture, which needs to be tuned for each application. In this study we propose to use simple systems based on di(meth)acrylate, polyimide and photoinitiator for the preparation of new photo-curable compositions.

Spectrum collapse in a 7-core Yb-doped fiber laser with an array of fs-inscribed fiber Bragg gratings.

Femtosecond inscription of fiber Bragg gratings (FBGs) in each core of a cladding-pumped seven-core Yb-doped fiber enables efficient (≈70%) 1064-nm lasing in a robust all-fiber scheme with ≈33 W power, nearly the same for uncoupled and coupled cores. However, the output spectrum is quite different: without coupling, seven individual lines corresponding to the in-core FBG reflection spectra sum up into a broad (0.22 nm) total spectrum, whereas the multiline spectrum collapses into a single narrow line at strong coupling.

Advanced distributed feedback lasers based on composite fiber heavily doped with erbium ions.

Specially designed composite heavily Er-doped fiber in combination with unique point-by-point inscription technology by femtosecond pulses at 1,026 nm enables formation of distributed-feedback (DFB) laser with ultra-short cavity length of 5.3 mm whose parameters are comparable and even better than those for conventional Er-doped fiber DFB lasers having much longer cavity. The composite fiber was fabricated by melting rare-earth doped phosphate glass in silica tube.

Durable shape sensor based on FBG array inscribed in polyimide-coated multicore optical fiber.

The paper presents a novel three-dimensional quasi-continuous shape sensor based on an FBG array inscribed by femtosecond laser pulses into a 7-core optical fiber with a polyimide protective coating. The measured bending sensitivity of individual FBGs ranges from 0.046 nm/m to 0.