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![(a) Refractive index profile, (b) 2.25 μm laser mode and (c) its vertical and horizontal line profiles of the waveguide written in the 45HfF4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}-10ZrF4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}-45BLAN glass. DIC image and writing parameters as in Fig. 4.](publication/363083792/figure/fig5/AS:11431281081497407@1661828173041/a-Refractive-index-profile-b-225-mm-laser-mode-and-c-its-vertical-and-horizontal.png)
(a) Refractive index profile, (b) 2.25 μm laser mode and (c) its vertical and horizontal line profiles of the waveguide written in the 45HfF4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}-10ZrF4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_4$$\end{document}-45BLAN glass. DIC image and writing parameters as in Fig. 4.
Source publication
Zirconium fluoride (ZBLAN) glass, the standard material used in fiber-based mid-infrared photonics, has been re-designed to enable the fabrication of high index-contrast low-loss waveguides via femtosecond laser direct writing. We demonstrate that in contrast to pure ZBLAN, a positive index change of close to 10⁻² can be induced in hybrid zirconium...
Citations
... We have shown that by replacing a certain fraction of zirconium atoms in the glass matrix with hafnium atoms, the inscription of waveguides with a strong positive index change becomes feasible. These waveguides feature a numerical aperture (NA) that is closely matched to that of commercially available ZBLAN fibers, enabling the realization of fiber-pigtailed optical chips for the mid-infrared spectral region [6]. An electron-cloud distortion effects caused by the presence of two glass formers with very different polarizability (zirconium and hafnium) has been identified as the main driver of this observed behavior. ...
... These waveguides can guide and confine light within the photonic crystal structure, allowing for efficient and controlled light propagation. Photonic crystal waveguides are crucial for routing and manipulating light signals in Photonic Integrated Circuits (PICs) [83,84]. ...
Photonic crystals have emerged as a fascinating field of research and development, offering unprecedented control over the propagation and manipulation of light. These artificial structures are engineered to have periodic variations in refractive index, enabling them to control the behavior of photons in a manner analogous to how crystals manipulate electrons. Recent advancements in photonic crystals have focused on expanding their capabilities and exploring new applications. These advancements and trends in photonic crystals demonstrate their potential to revolutionize various technological domains. From integrated photonics to sensing, quantum information processing to solar energy harvesting, photonic crystals offer unprecedented control over light and pave the way for innovative applications and devices.
... The field of silicon photonics is a rapidly developing area of research due to the fact that modern microelectronics are primarily based on silicon, making the development of photonic circuits in semiconductors crucial [1,2]. Although generating three-dimensional photonic circuits in dielectrics is relatively easy with ultra-short laser pulses, this technology cannot be adapted for silicon due to its high refractive index, which weakens the effective focusing strength and reduces the laser impact area [3][4][5][6][7]. Silicon's small band gap (~1.1 eV) and high number of free electrons also limit the use of commercially available lasers [6,7]. ...
In this study, we reconstructed the dynamics of the impact of mid-IR-range (4.6 μm) femtosecond laser pulses on bulk silicon under tight focusing conditions (NA = 0.5). Our experimental results show that under this impact, the deposited energy density (DED) reaches approximately 4 kJ/cm3 (at an energy slightly above the plasma-formation threshold). Initially, the femtosecond pulse energy is absorbed by the laser-induced plasma, with a lifetime of approximately 160–320 fs (depending on the laser pulse energy). The energy transfer from the plasma to the atomic subsystem occurs on a sub-ps timescale, which generates a shock wave and excites coherent phonons on a sub-ps scale. The shift of atoms in the lattice at the front of the shock wave results in a cascade of phase transitions (Si-X => Si-VII => Si-VI => Si-XI => Si-II), leading to a change in the phonon spectra of silicon.
... In terms of femtosecond laser waveguide inscription into fluoride glasses, it has been shown that index changes in the low 10 −3 range 12,13 can be achieved. However, a value of ∆n = 3 × 10 −3 in these glasses corresponds to a numerical aperture (NA) < 0.1 which is not compatible with commercially available mid-infrared fibres which typically feature NAs in the range 0.1 -0. 3. Very recently, we demonstrated that the positive index change in fluoride glasses can be increased to 8 × 10 −3 by modifying the composition of the bulk glass before fs-laser inscrition 14 . In silica glasses, fiber-coupled chips with excellent mode-matching have been demonstrated, yet at shorter wavelengths 15 . ...
... Brillouin frequency shifts (BFS) were measured using a 660 nm single frequency Cobolt Flamenco laser (HÜBNER Photonics) through a confocal microscope (CM1, TableStable Ltd). The details of BFS measurements can be found in reference 14 . ...
The femtosecond laser direct write technique was used to fabricate mid-infrared compatible waveguide couplers into Suprasil ® 3001, a fused silica glass with an OH-content of as low as {less than or equal to}1 parts per million. Smooth positive step- index change multi-scan waveguides were produced with a record-high index contrast of 1 × 10 ⁻² , measured directly using quadriwave lateral shearing interferometry. Waveguides were annealed at 400oC for 15 hours and found to be highly stable with only <5% reduction in positive index change. Brillouin microscopy and cathodoluminescence are introduced as novel tools that complement Raman mapping and electron microscopy for the investigation of the laser-induced structural changes within the glass matrix and it was found that although a uniform step index profile is observed across the entire guiding region, different physical mechanisms underpin the index change in the upper and lower sections of the waveguide cross-section, respectively. Waveguides were optimized for mode-matching with optical fibers for the 3.1 μm wavelength range and evanescent 4-port directional couplers with coupling ratios ranging from 5:95 to 50:50 were designed and fabricated. This demonstration opens the door to the development of fully integrated and temperature-stable hybrid chip/fiber systems for the important mid-infrared spectral range.
