Stephen A. Slattery

Fiber Bragg grating inscription by high-intensity femtosecond UV laser light: comparison with other existing methods of fabrication

By use of high-intensity (approximately 200 GW/cm2) femtosecond 264-nm laser light and a phase mask technique, Bragg grating inscription in a range of different photosensitive and standard telecom fibers (both H2-free and H2-loaded) was studied. The dependences of the induced refractive index modulation versus the incident fluence as well as the thermal decay curves were compared with similar dependences for gratings fabricated by other existing methods. It was shown that with high-intensity UV laser irradiation, two-quantum photoreactions occur in the irradiated fiber core, that result in a significant photosensitivity enhancement of the investigated fibers in comparison with conventional low-intensity 248-nm exposure (by 6-128 times, depending on fiber type and irradiation intensity).

Two-photon photochemical long-period grating fabrication in pure-fused-silica photonic crystal fiber

We report what is to our knowledge the first photochemical fabrication of a long-period grating in a pure-fused-silica photonic crystal fiber. The inscription technique is based on a two-photon absorption mechanism and does not require a specially designed photonic crystal fiber with a photosensitive Ge-doped core. The characteristic fluence value for the inscription is an order of magnitude less than that for a standard telecom fiber irradiated under similar conditions with the same grating parameters.

Absence of UV-induced stress in Bragg gratings recorded by high-intensity 264 nm laser pulses in a hydrogenated standard telecom fiber

We report on photochemical two-photon Bragg grating preparation in hydrogenated fiber without any UV-induced stress in the core or cladding, leaving only the color-center model responsible for refractive index changes for UV femtosecond irradiation. Without hydrogen loading strong stress changes are observed in the core and in the cladding indicating glass compaction. The irradiation does not change the inelastic strains, in contrast to H(2)-loading.

Ultraviolet poling of pure fused silica by high-intensity femtosecond radiation

We demonstrate UV poling of a pure fused silica sample by applying to it an electric field of 200 kV/cm and irradiating it with high-intensity (∼40GW∕cm2) femtosecond (220 fs) laser pulses at 264 nm.

Polarization properties of long-period gratings prepared by high-intensity femtosecond 352-nm pulses

We inscribed long-period gratings in a hydrogenated single-mode fiber (SMF-28) by high-intensity femtosecond near-ultraviolet pulses via a three-photon absorption mechanism. Due to energy deposition in the fiber cladding, such gratings are similar to those fabricated by CO/sub 2/ laser induced heating, mechanical pressure, or electric arc. We found that these gratings exhibit significant polarization properties.

TPA-induced long-period gratings in a photonic crystal fiber: inscription and temperature sensing properties

We report on the photochemical recording of long-period fiber gratings (LPFGs) in a photonic crystal fiber made of pure fused silica. Such inscription is based on two-photon absorption (TPA) of high-intensity (~300GW/cm) 264 nm 220 fs pulses and brings about LPFGs of high strength and narrow peak width. The characteristic fluence value for the inscription is 1 order of magnitude less than that for a standard telecom fiber irradiated under similar conditions. The temperature sensitivity of TPA-induced LPFGs is ~300 pm/ °C and overcomes that of LPFGs inscribed by other nonphotochemical methods by 2 orders of magnitude.

Strong long-period fiber gratings recorded at 352 nm

We describe long-period grating inscription in hydrogenated telecom fibers by use of high-intensity femtosecond 352 nm laser pulses. We show that this technique allows us to fabricate high-quality 30 dB gratings of 300 microm period and 2 cm length by use of a three-photon absorption mechanism.

Anisotropic Fiber Bragg Gratings Inscribed by High-Intensity Femtosecond-UV Pulses: Manufacturing Technology and Strain Characterization for Sensing Applications

We report the small-range strain characterization of anisotropic fiber Bragg gratings (FBGs) written by high-intensity femtosecond UV pulses. The FBGs are characterized with applied strain of 0-300 muepsiv using a high-speed Czerny-Turner spectrometer. The strain response slope is comparable to typical FBGs.

Investigation of long-period fiber gratings recorded by high-intensity femtosecond UV laser pulses

Using high-intensity (100-500 GW/cm2) 264 nm laser radiation, we fabricated long-period fiber gratings in telecom and photosensitive fibers, studied their temperature sensing properties and demonstrated the effect of thermal recovery of a LPFG resonance peak.

Polarization properties of long-period gratings prepared by high-intensity femtosecond 352nm pulses

We inscribed long-period gratings in a hydrogenated SMF-28 fiber by high-intensity femtosecond near-UV pulses via a three-photon absorption mechanism. Due to energy deposition in the fiber cladding, such gratings are similar to those fabricated by C02 laser induced heating, mechanical pressure or electric arc. We found that these gratings exhibit significant polarization properties.