Dual Regimes of Ion Migration in High Repetition Rate Femtosecond Laser Inscribed Waveguides

Fernandez, Toney Teddy; Sotillo, Belén; Hoyo, Jesús del; Vallés, Juan A.; Vázquez, Rebeca Martínez; Fernández, Paloma; Solı́s, J.

doi:10.1109/lpt.2015.2407378

Cited by 27 publications

(24 citation statements)

References 21 publications

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“…Figure and side inset), is enriched in La and depleted in K while the region below, dark contrasted in the SEM images, is depleted in La and shows a strong enrichment in K. The Z‐contrast of the SEM images is thus clearly consistent with the La‐K local distribution in the laser written structures. The compositional profiles also confirm that above a certain threshold, the La‐enrichment increases with the energy of the laser writing pulse, showing a relative increase of 22 and 28%, respectively, for the indicated pulse energies. These values would correspond to a refractive index contrast of, Δ n , ≈1.1 × 10 −2 and ≈1.4 × 10 −2 , respectively, for both waveguides at 670 nm according to the previously indicated estimate.…”

Section: Resultssupporting

confidence: 58%

Imaging Ellipsometry Determination of the Refractive Index Contrast and Dispersion of Channel Waveguides Inscribed by fs‐Laser Induced Ion‐Migration

Zarate

González²,

Funke³

et al. 2018

Physica Status Solidi (a)

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The measurement of the refractive index of optical waveguides is a difficult task that involves different methods, among which those based on the refracted near field determination (RNF) are likely the ones providing the best resolution. Still, most such methods lack spectral resolution, which impedes accessing the index dispersion of the waveguide, an essential parameter for many applications. In this work, the refractive index of channel waveguides produced by fs‐laser induced ion‐migration in a P2O5‐La2O3‐K2O‐based glass is measured by imaging ellipsometry. Along with EDX compositional maps and guiding performance, the dispersion and refractive index maps of several waveguides are measured. The results confirm that, in this glass, waveguides are formed due to an enrichment in La in the topmost part of the laser‐excited region which is accompanied by the cross migration of K toward the region underneath. Interestingly, the index contrast of the waveguides shows a wavelength‐independent behavior for wavelengths above ≈600 nm. This indicates that in the compositional range analyzed, La3+ ions linearly contribute to the glass polarizability due to the relatively large mass of La3+ ions and the relatively small size of the isolated La‐polyhedra accommodated in the phosphate glass network.

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Section: Resultssupporting

confidence: 58%

Imaging Ellipsometry Determination of the Refractive Index Contrast and Dispersion of Channel Waveguides Inscribed by fs‐Laser Induced Ion‐Migration

Zarate

González²,

Funke³

et al. 2018

Physica Status Solidi (a)

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“…Indeed, the ultimate reason making different species migrate in opposite directions is far from being understood. Above a certain threshold, in the case of phosphates [7,8,16] and borates [17] that are modified with alkali and rare earth (RE) oxides, the glass former ions remain relatively stable in their positions, while alkali and RE move in opposite directions. In the case of silicates, the general trend is to observe the glass former ions to move to the hottest region of the interaction region, while modifiers move outwards to the colder one [6,13].…”

Section: Introductionmentioning

confidence: 99%

Role of the La/K Compositional Ratio in the Properties of Waveguides Written by Fs-Laser Induced Element Redistribution in Phosphate-Based Glasses

Zarate¹,

Muñoz

Sotillo

et al. 2020

Materials

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The local modification of the composition of glasses by high repetition femtosecond laser irradiation is an attractive method for producing photonic devices. Recently, the successful production of waveguides with a refractive index contrast (Δn) above 10−2 by fs-laser writing has been demonstrated in phosphate glasses containing La2O3 and K2O modifiers. This large index contrast has been related to a local enrichment in lanthanum in the light guiding region accompanied by a depletion in potassium. In this work, we have studied the influence of the initial glass composition on the performance of waveguides that are produced by fs-laser induced element redistribution (FLIER) in phosphate-based samples with different La and K concentrations. We have analyzed the contribution to the electronic polarizability of the different glass constituents based on refractive index measurements of the untreated samples, and used it to estimate the expected index contrast caused by the experimentally measured local compositional changes in laser written guiding structures. These estimated values have been compared to experimental ones that are derived from near field images of the guided modes with an excellent agreement. Therefore, we have developed a method to estimate before-hand the expected index contrast in fs-laser written waveguides via FLIER for a given glass composition. The obtained results stress the importance of considering the contribution to the polarizability of all the moving species when computing the expected refractive index changes that are caused by FLIER processes.

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“…Strong changes in the aspect ratio of the waveguide structure were found when trying to increase the fluence either by increasing the average power or by reducing the speed or repetition rate. Such abrupt changes in the aspect ratio have been shown to be successfully controllable by spatial slit shaping enabling the control of the V-number of the waveguide quite efficiently [5,11].…”

Section: Resultsmentioning

confidence: 99%

Optical channel waveguides written by high repetition rate femtosecond laser irradiation in Li–Zn fluoroborate glass

Thomas

Fernandez

Solı́s

et al. 2018

J Opt

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Low loss, optical channel waveguides have been successfully produced by high repetition rate, femtosecond laser inscription in a Li-Zn fluoroborate glass (64.9B 2 O 3 + 25Li 2 O + 10ZnF 2 + 0.1Er 2 O 3 ). High quality waveguides were produced at 500 kHz, 1 MHz and 2 MHz laser repetition rates, showing a refractive index contrast in the range of 3-6×10 -3 depending on various fluences. Dependence of experimental parameters such as average laser power, pulse repetition rate and writing speed on the properties of fabricated waveguides has been discussed. The comparison of optical and compositional characterization techniques evidences an enrichment of B and Zn in the guiding region, while F migrates to the heat diffused region of the written structure.

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Dual Regimes of Ion Migration in High Repetition Rate Femtosecond Laser Inscribed Waveguides

Cited by 27 publications

References 21 publications

Imaging Ellipsometry Determination of the Refractive Index Contrast and Dispersion of Channel Waveguides Inscribed by fs‐Laser Induced Ion‐Migration

Imaging Ellipsometry Determination of the Refractive Index Contrast and Dispersion of Channel Waveguides Inscribed by fs‐Laser Induced Ion‐Migration

Role of the La/K Compositional Ratio in the Properties of Waveguides Written by Fs-Laser Induced Element Redistribution in Phosphate-Based Glasses

Optical channel waveguides written by high repetition rate femtosecond laser irradiation in Li–Zn fluoroborate glass

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