Carbon coatings on silica glass optical fibers studied by reflectance Fourier-transform infrared spectroscopy and focused ion beam scanning electron microscopy

Sensing carbon allotropes in protective coatings on optical fibers with far‐ and near‐field Raman spectroscopy and microscopy

“…Two types of samples were manufactured: (a) pristine fibers drawn with carbon coating only and (b) fibers drawn with carbon coatings and overcoated with a dual acrylate coating. The carbon-coating thickness was evaluated from the resistance measurements, assuming the resistivity value of 17.6 × 10 −6 Ω ⋅ m. [13] Consistency of the measurements was supported via FTIR reflection spectroscopy, using an approach developed previously. [27] For the pristine fibers, the carbon-coating thicknesses were 1.4, 4.0, 6.2, 9.8, 33.5, and 67.2 nm.…”

“…[10] A large arsenal of the methods such as scanning probe microscopy (SPM), vibrational (Raman and IR) spectroscopy, X-ray diffraction, and scanning electron microscopy provides an access to the intrinsic characteristics of the carbon coatings, for example, the graphitization degree, roughness, and platelet sizes. [11][12][13][14] Most popular tools are both atomic force microscopy (AFM) and Raman spectroscopy, which provide information on the roughness and the chemical structure of carbonaceous coatings. [15,16] In the latter case, a ratio of two intense peaks G and D, assigned to the graphite mode (with symmetry E 2g ) at 1,590 cm −1 and the disorder-induced graphite mode (with symmetry A 1g ) at 1360 cm −1 , respectively, is used as a quantitative indicator of presence of crystalline and amorphous fractions in the resulting carbon layer.…”

“…It is well known that carbon coatings are mostly composed of graphite‐like crystals and interstitial amorphous carbon . A large arsenal of the methods such as scanning probe microscopy (SPM), vibrational (Raman and IR) spectroscopy, X‐ray diffraction, and scanning electron microscopy provides an access to the intrinsic characteristics of the carbon coatings, for example, the graphitization degree, roughness, and platelet sizes . Most popular tools are both atomic force microscopy (AFM) and Raman spectroscopy, which provide information on the roughness and the chemical structure of carbonaceous coatings .…”

Hermetic Carbon Coatings for Electro-Thermal All-Fiber Phase Modulators

“…This thickness was estimated from transmission electron microscopy measurements. The coating had an electrical resistance in the range from 6.3 kΩ/cm to 3.7 kΩ/cm in the highest conductivity sample, the variation arising primarily from resistivity change from fiber to fiber [8]. The deposition of the thin carbon layer on the fiber cladding surface was performed by chemical vapor deposition from a hydrocarbon gas during the fiber drawing procedure at 1850ºC.…”

“…where 𝑃 is the power being dissipated by the heated body, 𝑆 is the area of its external surface, and the factor ℎ accounts for the efficiency of the convective process. This parameter usually ranges from 2 to 25 W/(m 2 K) for free convection in gases [8].…”