Spatially resolved cross-sectional refractive index profile of fs laser–written waveguides using a genetic algorithm

Drouin, Antoine; Lorre, Pierre; Boisvert, Jean-Sébastien; Loranger, Sébastien; Iezzi, Victor Lambin; Kashyap, Raman

doi:10.1364/oe.27.002488

Cited by 11 publications

(3 citation statements)

References 26 publications

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“…This microscopy interferometric systems measure the relative phase change from the surrounding and, providing knowledge about 2D cross section profile of the inscription, could determine the RI change profile by using the following Eq. ( 1 ) 23 . where, Δφ is the measured phase change, λ the wavelength of measurement, which is 633 nm for that system and h is the height of the structure.…”

Section: Methodsmentioning

confidence: 99%

Fs laser written volume Raman–Nath grating for integrated spectrometer on smartphone

Boisvert,

Loranger,

Kashyap

2023

Sci Rep

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In this work we demonstrate the integration of a spectrometer directly into smartphone screen by femtosecond laser inscription of a weak Raman–Nath volume grating either into the Corning Gorilla glass screen layer or in the tempered aluminosilicate glass protector screen placed in front of the phone camera. Outside the thermal accumulation regime, a new writing regime yielding positive refractive index change was found for both glasses which is fluence dependent. The upper-bound threshold for this thermal-accumulation-less writing regime was found for both glasses and were, respectively at a repetition rate less than 150 kHz and 101 kHz for fluence of 8.7 × 106 J/m2 and 1.4 × 107 J/m2. A weak volume Raman–Nath grating of dimension 0.5 by 3 mm and 3 μm pitch was placed in front of a Samsung Galaxy S21 FE cellphone to record the spectrum using the 2nd diffraction order. This spectrometer covers the visible band from 401 to 700 nm with a 0.4 nm/pixel detector resolution and 3 nm optical resolution. It was used to determine the concentration detection limit of Rhodamine 6G in water which was found to be 0.5 mg/L. This proof of concept paves the way to in-the-field absorption spectroscopy for quick information gathering.

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Section: Methodsmentioning

confidence: 99%

Fs laser written volume Raman–Nath grating for integrated spectrometer on smartphone

Boisvert,

Loranger,

Kashyap

2023

Sci Rep

Self Cite

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“…Using this setup, we were able to extract the phase change between the unexposed materials and the exposed area and calculate the maximum phase change. Provided the height of the affected area is known from the waveguide’s dimensions 11 , (which is obtained by simple end-face cross-section imaging of the waveguide, as shown in Fig. 1 c,d, the refractive index change can be calculated simply using Eq.…”

Section: Methodsmentioning

confidence: 99%

Photosensitization agents for fs laser writing in PDMS

Boisvert

Hlil

Loranger

et al. 2022

Sci Rep

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This study aims at identifying compounds incorporated into Polydimethylsiloxane (PDMS) which produce large refractive index change under fs laser exposition, potentially leading to optimal writing of waveguides or photonic devices in such a soft host. Germanium derivative, titania and zirconite derivatives, benzophenone (Bp), irgacure-184/500/1173 and 2959 are investigated. We show a mapping of the RI index change relative to the writing speed (1 to 40 mm/s), the repetition rate (606 to 101 kHz) and the number of passes (1 to 8) from which we establish quantitative parameters to allow the comparison between samples. We show that the organic materials, especially irgacure-184 and benzophenone yield a significantly higher maximum refractive index change in the order of 10−2. We also show that the strongest photosensitivity is achieved with a mixture of organic/organo-metallic material of Bp + Ge. We report a synergetic effect on photosensitivity of this novel mixture.

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“…One potential problem usually during the fabrication process is the volatilization of the dopant (e.g., Ge or P) from the innermost layers during the collapsing stage, which will result in the RI dip at the center of the fiber cores. This dip has been observed not only in the passive fibers for low-power applications [28][29][30][31] but also in the active fibers for high-power applications [32][33][34][35]. To mitigate this phenomenon, some approaches such as etching the innermost layers [36], modifying the doping concentration [37], and controlling the temperature [38] have been proposed and verified in recent years.…”

Section: Introductionmentioning

confidence: 99%

Impact of the central refractive index dip of fibers on high-power applications

Chen

Ren

et al. 2023

Front. Phys.

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Central refractive index dip is a common phenomenon in the fibers fabricated by the modified chemical vapor deposition (MCVD) technology, which is the main fabrication technique for high-power laser fibers. In this paper, we present a numerical analysis of the dip effect on high-power-related parameters for the first time, to the best of our knowledge. Three aspects including mode field parameter, beam quality, and bending performance are studied under different dip parameters and bending radii. It is found that the dip is possible to increase the effective mode area and the bending loss, which offers a flexible way to suppress the non-linear effects and filter the higher-order modes by optimizing the dip parameters. Besides, different from the mode area and bending loss, beam quality exhibits an interesting trend when the dip radius increases. The results could facilitate a comprehensive understanding of the dip fiber properties, which also offer guidance to evaluate and design the fiber with central refractive index dip for high-power applications.

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Spatially resolved cross-sectional refractive index profile of fs laser–written waveguides using a genetic algorithm

Cited by 11 publications

References 26 publications

Fs laser written volume Raman–Nath grating for integrated spectrometer on smartphone

Fs laser written volume Raman–Nath grating for integrated spectrometer on smartphone

Photosensitization agents for fs laser writing in PDMS

Impact of the central refractive index dip of fibers on high-power applications

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