Abstract Femtosecond laser filaments are formed by surface aberration to open nano‐hole arrays, passing through the silica cladding and guiding core cross‐section of a standard telecommunication fiber. The hollow filament grating presents strong capillarity effect draw nematic liquid crystal (NLC) into homogeneous alignment with cylindrical walls high birefringent response in second‐order Bragg stopband. NLC provides extinction ratio up 20 dB over ≈5 nm band only moderate insertion loss...

Embedding strong photonic stopbands into traditional optical fibre that can directly access and sense the outside environment is challenging, relying on tedious nano-processing steps result in fragile thinned fibre. Ultrashort-pulsed laser filaments have recently provided a non-contact means of opening high-aspect ratio nano-holes inside bulk transparent glasses. This method has been extended here to fibre, resulting high density arrays filamented holes penetrating transversely through...

Fiber Bragg gratings (FBGs) are useful components in fiber optic sensing systems, which can be highly multiplexed and distributed. In recent years, fabrication using ultrafast lasers has made these devices much more versatile robust, but questions concerning their high-temperature performance remain. The wavelength resonance of an FBG is naturally sensitive to various parameters its environment; particular, changes the temperature or strain a tend induce observable shifts wavelength. Thus,...

Femtosecond laser irradiation is applied to a single‐mode optical fiber embed filament array through the silica cladding and guiding core form chirped Bragg gratings. Unlike planar‐shaped refractive index modification, long uniform facilitates efficient scattering into azimuthally narrowed radiation modes, external transverse cladding. Chirping of grating period further provides spectral focusing. The combined azimuthal focusing permits lens‐less recording bright high‐resolution spectra...

1000°C-resistant Bragg gratings (i.e., Type-II gratings) with a 300 nm period are fabricated in non-photosensitized silica-based optical fibers using tightly focused ultraviolet/visible (400 nm) femtosecond pulses and phase mask. Five millimeter-long -10 dB transmission dip -0.1 off-resonance insertion loss demonstrated. Inscription of such is also possible through protective acrylate coatings on the fiber. The wavelength drift changes fiber monitored course isothermal annealing performed at...

Filament arrays were inscribed off-axis in the core of standard single-mode telecommunication fiber, using femtosecond laser pulses. The flexible line-by-line writing formed uniform, parallel filaments, permitting Bragg grating sensing photoelastic response from inside narrow plane. Active monitoring resonance wavelength while driving a lateral fiber tip displacement directly informed on mechanics when coupled with opto-mechanical modelling. Overlaying and orthogonal gratings further...

Aberrated femtosecond laser pulses were applied to telecommunication fiber open nano-filament arrays through the silica cladding and waveguide cross-section. Strong photonic bandgap response from n-shifted, second-order Bragg gratings enabled high resolution refractive index sensing. ©2020 The Author(s)

A super-efficient all-fiber visible spectrometer with sub-nanometer resolution is fabricated using one infrared femtosecond laser pulse and a phase mask. The strong light outcoupling from the fiber due to micropores formed in its core.

Fiber Bragg Grating (FBG) relative humidity (RH) sensors were written in 50 μm diameter fibers through the polyimide coating. Thickening resulted highest sensitivity reported for coated FBG RH sensors.

All-fiber visible spectrometers with a sub-nanometer resolution and record-high light outcoupling (70%) are fabricated using violet (400 nm) near-infrared (800 femtosecond laser pulses the phase mask technique. The based on highly localized uniform Bragg gratings produced by tightly focusing into core of single-mode fibers. unique nanoscale morphology resultant ensures very strong from fiber, while bending fiber provides capability to define an efficient all-fiber spectrometer.

Femtosecond laser light has been shaped with a spatial modulator (SLM) to generate optically thin, aberration-free sheets of uniform intensity for inscription fiber Bragg gratings (FBGs) inside the core SMF-28 telecommunication fiber. The combination flexible beam shaping and sheet-by-sheet writing offers facile means in controlling coupling cladding or radiation modes while facilitating spectral tuning flexibility that is not available interference-based techniques. Spectral responses first...

Femtosecond laser welding was extended to optical silica fiber (SMF-28) by focusing through fused substrates and ferrules form all-glass weld seams. Laser radiation focused into the cladding create a zone, which drove molten glass fill as much 3 𝜇𝑚 gap around contact line crack free pseudo-continuous seams along line. The strong up 30 wide were generated in fiber-to-plate fiber-to-ferrule geometries without inducing photochemical or thermal degradation of Bragg grating (FBG) positioned only...

Miniaturization of astronomical instruments for high-resolution cross-correlation spectroscopy exoplanet analysis may be achieved using existing photonic platforms and technologies. Arrays fibre Bragg gratings (FBGs) inscribed into optical to form a target-tailored instrument spectrum offering flexible modulation during operation. This paper presents example spectra the first such designed spectroscopy, fabricated by point-by-point writing with femtosecond laser in core single-mode...

A chirped-array of filament tracks, formed in single-mode fiber with femtosecond laser pulses, provided radiative emission and lens less focusing to define an all-fiber spectrometer 0.3 nm resolution the visible spectrum.

Femtosecond laser pulses were shaped into uniform intensity sheets for point-by-point writing of micro-volume gratings inside single-mode optical fiber core, opening flexible means tailoring spectral properties Bragg grating devices.

A two-dimensional (2D), point-by-point writing technique of forming filament arrays with femtosecond laser pulses was applied inside single-mode optical fiber to open new opportunities for 2D photonic bandgap engineering and highresolution spectroscopy. small grating period ~300 nm provided first-order diffraction externally the cladding, spectral, blazing, self-focusing properties tailored by varying 1D design. The spectral lens-less, all-fiber spectrometer have been tuned dimension,...

Frequency resolved optical gating is applied to study the temporal structure and spectrum of first anti-Stokes. We observe a double peaked, red-shifted spectrum. Together with phase information, we think there two separated processes in Multi-frequency Raman Generation.

Point-by-point femtosecond laser writing of filaments was used to open high aspect ratio nano-holes transversely through the core a single-mode telecommunication fiber (SMF-28). On infiltration with nematic liquid crystal, small 200 nm diameter holes induced strong capillary alignment facilitate birefringence responses when filament aligned into second-order (~1 micrometer period) Bragg arrays. Geometric arrangement nano-hole arrays provided unique opportunity designing customized all-fiber...

All-Fiber Spectrometers In article number 2000026, Abdullah Rahnama and coworkers have harnessed femtosecond laser writing of high aspect ratio filament tracks to form fiber Bragg gratings in single-mode optical fiber. The geometry favored radiative emission into narrow azimuthal zones outside the cladding by first-order diffraction. A chirped array enabled lens-less focusing, define a compact all-fiber spectrometer with moderately 0.3 nm resolution for light spanning full visible spectrum.