Ligand-Driven and Full-Color-Tunable Fiber Source: Toward Next-Generation Clinic Fiber-Endoscope Tomography with Cellular Resolution

Abstract

In many biomedical applications, broad full-color emission is important, especially for wavelengths below 450 nm, which are difficult to cover via supercontinuum generation. Single-crystalline-core sapphires with defect-driven emissions have potential roles in the development of next-generation broadband light sources because their defect centers demonstrate multiple emission bands with tailored ligand fields. However, the inability to realize high quantum yields with high crystallinity by conventional methods hinders the applicability of ultra-broadband emissions. Here, we present how an effective one-step fiber-drawing process, followed by a simple and controllable thermal treatment, enables a low-loss, full-color, and crystal fiber-based generation with substantial color variability. The broad spectrum extends from 330 nm, which is over 50 nm further into the UV region than that in previously reported results. The predicted submicrometer spatial resolutions demonstrate that the defect–ligand fields are potentially beneficial for achieving in vivo cellular tomography. It is also noteworthy that the efficiency of the milliwatt-level full-color generation, with an optical-to-optical efficiency of nearly 5%, is the highest among that of the existing active waveguide schemes. In addition, direct evidence from high-resolution transmission electron microscopy together with electron energy loss spectroscopy and crystal-field ligands reveals an excellent crystalline core, atomically defined core/cladding interfacial roughness, and significant enhancements in new laser-induced electronic defect levels. Our work suggests an inexpensive, facile, and highly scalable route toward achieving cellular-resolution tomographic imaging and represents an important step in the development of endoscope-compatible diagnostic devices.

Properties of waveguides filled with anisotropic metamaterials

“…Another good example of a radially structured metamaterial waveguide is a hybrid-glass metamaterial fiber, which was reported for nonlinear effects [70]. This waveguide is fabricated by a laser-based fiber drawing technique [71,72]. To fabricate such a waveguide, sapphire (α − Al 2 O 3 ) was taken as a seed dielectric core and dendrite crystalline γ − Al 2 O 3 was deposited on it.…”

Laser Floating Zone Growth: Overview, Singular Materials, Broad Applications, and Future Perspectives

“…This approach helps laser processing and allows enhancing the structural characteristics of the single-crystal fiber produced. Similarly, in the last 10 years, cladded, single-crystalline fibers, mainly used as amplifiers, have been produced from bulk crystal seeds covered by Sol-Gel or embedded into silica or borosilicate hollow tubes, among other coating approaches [35][36][37][38][39]. Furthermore, some works from Rutgers University (Piscataway, NJ, USA) reported the growth from Pt wires together with the use of seed crystals or presintered ceramics as feed rods [40][41][42].…”

“…[97], demonstrating the suitability of the fibers produced to be successfully employed for high-temperature sensing, as Ye et al, in 2005 [57], also similarly tested later for YAG:Cr 3+ . Likewise, Lai et al in 2016 grew borosilicate-cladded, single-crystalline-core sapphire fibers suitable to be employed in biomedical applications, such as light sources for endoscopy [39]. It must be highlighted that Lai et al, in 2018, also demonstrated a facile and scalable approach for the transformation of a centrosymmetric sapphire (α-Al 2 O 3 ) crystal to a large-scale 3D metamaterial (Si 4+ :γ-Al 2 O 3 ) with sub-wavelength fine structures [104].…”

“…Niobates grown by LFZ since the review byRudolph and Fukuda in 1999 [8]. TiO 2 ) crystals have been continually produced by this technique, improving both production efficiency and material properties, as can be deduced from work published in the last few years[22,23,32,39,42,[96][97][98][99][100][101][102][103][104] (Table3). Indeed, doping of sapphire with Cr 3+ and Er 3+ , or even codoping with Er 3+ /Yb 3+ , was achieved through LHPG by Seat in 2001[96] andSeat and Sharp in 2003 …”

Triple-gene deletion for osteocalcin significantly impairs the alignment of hydroxyapatite crystals and collagen in mice

“…With the development of technology, more methods could be used to assess bone microarchitecture and mineral composition. Conventional X-ray diffraction (XRD) can give direct information about the crystalline quality and size as well as the presence of defects in the crystal ( Lai et al, 2016 ). In terms of evaluating bone mineralization, quantitative backscattered electron imaging (qBEI), quantitative magnetic resonance (QMR), micro-computed tomography (μCT), Fourier-Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy analysis (RS) can be used to quantify the degree of bone mineralization and obtain bone microstructure data with different resolutions ( Donnelly, 2011 ).…”