The formation of two grating types in SMF-28 fiber by focusing 125 fs, 0.5-2 mJ pulses through a phase mask onto sample is studied. first type, specified as type I-IR, occurs below the damage threshold medium. scaling behavior I-IR gratings with field intensity and annealing properties suggests that their related to nonlinear absorption processes, possibly resulting color center formation. second denoted II-IR, coincidentally white light generation within fiber. These II-IR are stable at...

High-quality retroreflecting fiber Bragg gratings were written in standard Ge-doped telecom (Corning SMF-28) after a few minutes exposure with pulsed 800-nm, 120-fs laser radiation by use of deep-etch silica zero-order nulled phase mask optimized for 800 nm. Induced index modulations 1.9 x 10(-3) achieved peak power intensities 1.2 10(13) W/cm2 without any sensitization. The are stable and did not erase 2 weeks at 300 degrees C. primary mechanism induced change results from structural...

We report for the first time inscription of retro-reflective Bragg gratings in multimode crystalline sapphire fiber. The were fabricated using 800-nm femtosecond laser radiation and a phase mask. grating behavior was investigated up to 1500/spl deg/C with no detectable reduction reflectivity or hysteresis resonance. Measurements change effective index fiber as function temperature are reported performance sensor is evaluated.

Femtosecond laser pulses at 800 nm and 120 fs were used to fabricate high-quality retroreflecting fiber Bragg gratings in standard Ge-doped telecom (Corning SMF-28) all-silica-core Fluorine doped cladding single-mode using a deep-etch silica zero-order nulled phase mask. Induced index modulations of 1.9/spl times/10/sup -3/ achieved with peak power intensities 2.9/spl 12/ W/cm/sup 2/ without any sensitization such as hydrogen loading. The have annealing characteristics similar type II damage...

Using an ultrafast Ti:sapphire 800 nm laser and a phase mask, fibre Bragg gratings (FBGs) with high thermal stability were fabricated in Ge-doped SMF-28 for sensor applications subjected to long annealing tests at 1000 °C. FBGs that maintained more than 99.95% reflectivity after several hundred hours this temperature are demonstrated. The perform well cycling experiments up °C, hysteresis the wavelength response was not detected. At of 1050 permanent drift central is observed which...

We present fiber Bragg grating pressure sensors in air-hole microstructured fibers for high-temperature operation above 800°C. An ultrafast laser was used to inscribe Type II two-hole optical fibers. The resonance wavelength shift and peak splits were studied as a function of external hydrostatic from 15 psito2000 psi. sensor shows stable reproducible demonstrate multiplexible technology environment using single single-fiber feedthrough.

A novel highly sensitive ultrasound sensor based on a random fiber laser is proposed and demonstrated for the first time, to best of our knowledge. The constructed with erbium-doped gain. grating provides random-distributed feedback acts as an sensing head. can operate in single-mode lasing scenario, which offers linear pure temporal responses broadband ultrasonic acoustic emission from 20 kHz 0.8 MHz. multiple-interfering reflection spectrum large number steep peak areas over broad spectral...

Since its demonstration in 2003, Bragg grating inscription with high-power femtosecond pulse duration infrared sources and phase masks has proven to be an effective far more versatile approach fabrication than the conventional ultraviolet laser technique. The ultrafast IR laser-based process allows for creation of structures glassy crystalline material waveguides that are not typically UV-photosensitive, thereby creating new applications gratings. In this paper we will review studies have...

Plane-by-plane fabrication of fiber Bragg gratings in optical fibers using a short-pulse femtosecond IR laser is proposed and demonstrated.By incorporating cylindrical lens the setup, plane index modification can be directly inscribed core by single pulse.The planes are produced free-standing without an oil immersion objective.This plane-by-plane method simplifies direct grating inscription process allows for complicated structures.

Multi-wavelength (MW) laser sources with high optical signal-to-noise ratios (OSNR) are of great interest for communications ultrahigh data capacity as well microwave and terahertz photonics. In this paper, we report the first demonstration MW Brillouin random fiber in telecom spectral window around 1.5 μm based on a unique grating (RFG). Random feedback by enhanced distributed Rayleigh scattering from RFG basically enables high-efficiency lasing resonance Stokes wave via stimulated fibers....

This paper reports the testing results of radiation resistant fiber Bragg grating (FBG) in random air-line (RAL) fibers comparison with FBGs other radiation-hardened fibers.FBGs RAL were fabricated by 80 fs ultrafast laser pulse using a phase mask approach.The gratings tests carried out core region 6 MW MIT research reactor (MITR) at steady temperature above 600°C and an average fast neutron (>1 MeV) flux >1.2 × 10 14 n/cm 2 /s.Fifty five-day FBG sensors showed less than 5 dB reduction peak...

Fiber Bragg gratings were fabricated in all-silica core fiber by focusing 125-fs 800-nm pulses with an 80-mm lens through a phase mask 4.28-microm pitch onto sample. When the phase-mask-fiber separation was 5 mm observed structure clearly result of two-beam interference between +/- 1 orders. The elimination remaining 9 orders is consequence walk-off experienced and short duration femtosecond pulse. This effect unique to fabrication sources would not be longer pulse or incoherent UV sources.

The fabrication of refractive microlens arrays by the technique excimer laser ablation doped amorphous Teflon combined with subsequent annealing and melting produced polymer islands is described. microlenses obtained are optically clear from far UV (190 m) to near IR (2000 nm) good optical quality. They vary in size 50 385 µm diameter numerical apertures between 0.2 0.3. Utilization these for material processingby lasers at 193 nm demonstrated, possible applications discussed.

We present, for the first time to our knowledge, a dual strain/temperature sapphire fiber Bragg grating sensor. Temperature and strain coefficients of are evaluated. By recording blackbody radiation level above 650 degrees C, wavelength shifts due temperature can be decoupled from those strain.

A novel multiparameter fiber-optic sensor based on a femtosecond laser micromachined random grating is proposed and demonstrated to realize simultaneous measurement of temperature, axial strain, surrounding refractive index. wavelength-division spectral cross-correlation algorithm adopted extract the phase variation induced shift responding different external disturbances. Sensitivities 10.32 pm/°C, 1.24 pm/με, -1520.6 pm/RIU were achieved for index, respectively. The fiber without mask...

By using the plane-by-plane grating inscription method with an fs-IR laser, random fiber gratings low laser-induced loss were fabricated in SMF-28 for distributed temperature sensing. Compared to conventional having broadband backscattering enhancement, demonstrated has a well defined narrower bandwidth of higher level, and lower loss, which are critical long-haul sensor systems high measurement accuracy. Experimental results showed that by along technique optical frequency-domain...

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,...

The damage and transmission properties of selected commercially available fused silica fibers have been measured as a function excimer laser wavelength. Two-photon absorption color center formation in currently limit the use these at wavelengths 193 nm (ArF) 248 (KrF).

Fiber Bragg gratings were written in pure silica photonic crystal fibers (PCFs) and PCF tapers with 125-fs 800-nm infrared radiation. High reflectivities achieved short exposure times the tapers. Both multimode single-mode grating reflections fiber

Aluminosilicate fibers have very low Brillouin scattering gain coefficients, making them interesting for nonlinear optical applications.We manufactured Bragg gratings in high (30 mol.%) and (4 alumina content fiber using 800 nm femtosecond pulse duration radiation a phase mask.Grating spectral characteristics thermal behavior are presented.Index modulations >10 -3 were generated fundamental pitched gratings, -4 higher-order gratings.Gratings annealed at temperatures up to 900°C.Type II...

Periodic planar nanostructures are found in Type II-IR Bragg gratings produced SMF-28 fiber by side-illuminating it with infrared femtosecond-laser pulses through a phase mask. The aligned perpendicular to the laser polarization, as demonstrated using scanning electron microscopy analysis of cleaved samples. Dark field optical is employed for real-time monitoring structural changes occurring inside during inscription process.