X-ray preconditioning for enhancing refractive index contrast in femtosecond laser photoinscription of embedded waveguides in pure silica

Royon, Maxime; Marin, Emmanuel; Girard, Sylvain; Boukenter, Aziz; Ouerdane, Y.; Stoian, Razvan

doi:10.1364/ome.9.000065

Cited by 13 publications

(14 citation statements)

References 27 publications

(27 reference statements)

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“…Moreover we also observed, in the Raman spectra acquired for the waveguide written with at 343 nm laser and pulse energy of 0.2 µJ, the laser-induced band at 896 cm −1 : this band was observed in other samples under different classes of irradiations [27,28]. Following the Ref.…”

Section: Pl and Raman Measurementssupporting

confidence: 64%

“…Indeed, using different experimental conditions, it is possible to obtain ∆n comparable or higher, eg. by using 800 nm femtosecond laser pulses [28]. The explanation of this efficiency could be linked to the different energies of the absorbed photons: the multiphoton ionization, that is the main process for the plasma generation, requires ∼3 photons at 343 nm and ∼8 at 1030 nm, making the non-linear absorption much efficient in the UV domain, as already observed in [31].…”

Section: Optical Propertiesmentioning

confidence: 88%

“…For instance, the waveguides inscribed with the near-IR laser reach the Type II before to attain ∆n comparable with those of waveguides inscribed at 343 nm. This is not a general rule, since different experimental conditions could provide similar ∆n using 800 nm femtosecond pulses [28]. In conclusion, to estimate the contribution of the defects to the ∆n with respect the densification, we have submitted our written waveguides to two thermal treatments: the first temperature, 500°C, was chosen to anneal almost all the NBOHCs, while the second one, at 750°C, was selected to anneal almost all the laser-induced absorbing defects.…”

Section: Discussionmentioning

confidence: 99%

“…Measurements are based on the estimation of the NA, injecting light directly into the waveguides, acquiring the far field mode waist at different distances. In this way, by the relation NA = √ 2n∆n it is possible to estimate the induced refractive index change [28]. The obtained value should be interpreted as an average index change over the whole VIS-NIR range and along the cross section of the inscribed waveguides, without any pretense of being an exact value of ∆n, but only an estimation.…”

Section: Optical Propertiesmentioning

confidence: 99%

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Near-IR- and UV-femtosecond laser waveguide inscription in silica glasses

Michele¹,

Royon²,

Marin³

et al. 2019

Opt. Mater. Express

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The influence of laser parameters on silica based waveguide inscription is investigated by using femtosecond laser pulses at 1030 nm (near-IR) and at 343 nm (UV). Negative phase contrast microscopy technique is used to measure the refractive index contrast for different photo-inscribed waveguides and shows the effects of both laser wavelength and scanning speed. In particular, UV photons have a higher efficiency in the waveguide production process as also confirmed by the lower optical losses at 1550 nm in these waveguides. These measurements are combined with micro-Raman and photoluminescence techniques, highlighting that laser exposure induces both structural modification of the silica and point defects generation. The contribution of induced defects to the total refractive index change is singled out by applying two different thermal treatments on the waveguide. The first, up to 500°C, is able to remove the most of the induced non-bridging-oxygen-hole-centers (NBOHCs) while the second up to 750°C erases almost all absorbing induced defects, highlighting the strong contribution of additional defects, not yet identified.

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Section: Pl and Raman Measurementssupporting

confidence: 64%

Section: Optical Propertiesmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

See 2 more Smart Citations

Near-IR- and UV-femtosecond laser waveguide inscription in silica glasses

Michele¹,

Royon²,

Marin³

et al. 2019

Opt. Mater. Express

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“…Type I fs-FBGs mostly are based on a glass fictive temperature T f increase [56] when the duration of the heat pulse corresponding to the light energy is greater than the glass relaxation time η(T)/G(T) (shear viscosity / shear modulus) with a partial contribution (typically 20%) of point defects [57]. However Type I fs-FBGs can be completely erased by annealing at temperatures exceeding 800°C.…”

Section: Femtosecond Fbgs (Type II and Iii Fbgs)mentioning

confidence: 99%

Overview of high temperature fibre Bragg gratings and potential improvement using highly doped aluminosilicate glass optical fibres

et al. 2019

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In this paper, various types of high temperature fibre Bragg gratings (FBGs) are reviewed, including recent results and advancements in the field. The main motivation of this review is to highlight the potential of fabricating thermally stable refractive index contrasts using femtosecond (fs) nearinfrared radiation in fibres fabricated with non-conventional techniques, such as the molten core method. As a demonstration of this, an yttrium aluminosilicate (YAS) core and pure silica cladding glass optical fibre is fabricated and investigated after being irradiated by an fs laser within the Type II regime. The familiar formation of nanogratings inside both core and cladding regions are identified and studied using birefringence measurements and scanning electron microscopy. The thermal stability of the Type II modifications is then investigated through isochronal annealing experiments (up to T=1100°C; time steps, Δt=30 min). For the YAS core composition, the measured birefringence does not decrease when tested up to 1000°C, while for the SiO 2 cladding under the same conditions, its value decreased by ∼30%. These results suggest that inscription of such 'Type II fs-IR' modifications in YAS fibres could be employed to make FBGs with high thermal stability. This opens the door toward the fabrication of a new range of 'FBG host fibres' suitable for ultra-high temperature operation. ORCID iDsMaxime Cavillon https:/ /orcid.org/0000-0003-1341-6294 Peter Dragic https:/ /orcid.org/0000-0002-4413-9130 Figure 5. Normalized retardance (averaged over the 0.1 to 1.0 μJ pulse energy range) as a function of temperature for YAG-derived fibre at the core center (YAS) and in the cladding (SiO 2 ), for both // and ⊥ configurations. The measurements were performed at room temperature.

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3D Laser Engineering of Molten Core Optical Fibers: Toward a New Generation of Harsh Environment Sensing Devices

Wang

Cavillon

Ballato

et al. 2022

Advanced Optical Materials

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kW fiber lasers, long-term optical data storage such as Microsoft's "project silica", [1] etc.) and optical sensing (structural health monitoring of engines, deep drilling). [2] In most applications operating in a HT environment, refractory crystalline oxide materials such as alumina (Al 2 O 3 ) or zirconia (ZrO 2 ) are candidates of choice, due to their high melting points and good resistance to oxidation and abrasion. Furthermore, directionally solidified eutectic ceramics (e.g., unidirectionally solidified Al 2 O 3 /oxide eutectic composite made of perovskite or garnet phase) also can improve thermal stability, [3] as demonstrated for instance in aircraft gas turbines and thermal power generation systems (e.g., operation for 1000 h at 1700 °C).However, other HT applications, such as long-lived data storage for the zettabyte era [1] or optical sensors (down-hole oil/gas exploration, monitoring of structure health, temperature regulation of engines, etc.) require using glass materials that can be functionalized and shaped into chips, disks, planar waveguides or optical fibers. Both the materials and geometric designs need be considered due to practical demands, such as compactness and lightness, flexibility, high-transparency, fast and complex manufacturing shaping, chemical/radioactive/ electromagnetic resistance, and low cost. For these reasons, Aluminosilicate glasses offer wide-ranging potential as enabling materials for a new generation of optical devices operating in harsh environments.In this work, a nonconventional manufacturing process, the molten core method, is employed to fabricate and study sapphire (Al 2 O 3 ) and YAG (yttrium aluminum garnet) derived all-glass silicate optical fibers in which a femtosecond (fs) laser is used to imprint oriented nanostructures inside the fiber cores. Both writing kinetics and thermal stability of the laser-modified regions are investigated over a wide temperature range (20-1200 °C). The laser-imprinted modifications in these high alumina-content fibers exhibit improved thermal stability with respect to commercial pure silica and GeO 2doped silica analogs. Furthermore, optical devices in the form of Rayleigh backscattering and fiber Bragg grating sensors are fabricated to demonstrate the high-temperature sensitivity and stability of these nonconventional fibers. This functionalization of aluminosilicate fibers by fs-laser direct writing opens the door to a new generation of optical devices suitable for high-temperature operation.

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X-ray preconditioning for enhancing refractive index contrast in femtosecond laser photoinscription of embedded waveguides in pure silica

Cited by 13 publications

References 27 publications

Near-IR- and UV-femtosecond laser waveguide inscription in silica glasses

Near-IR- and UV-femtosecond laser waveguide inscription in silica glasses

Overview of high temperature fibre Bragg gratings and potential improvement using highly doped aluminosilicate glass optical fibres

3D Laser Engineering of Molten Core Optical Fibers: Toward a New Generation of Harsh Environment Sensing Devices

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