Characteristics of carbon coatings on optical fibers prepared by radio-frequency plasma enhanced chemical vapor deposition with different H2/C2H2 ratios

• Published in: Thin solid films 2010-10, Vol.518 (24), p.7492-7496
• Main Authors: LIN, Hung-Chien, YU, Jen-Feng, SHIUE, Sham-Tsong, LIN, Hung-Yi
• Format: Article
• Language: English
• Subjects: Bonding; Carbon; Chemical bonds; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Coatings; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Graphite; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical coatings; Optical elements, devices, and systems; Optical fibers; Optics; Physics; Plasma enhanced chemical vapor deposition; Surface and interface electron states; Surface states, band structure, electron density of states; Theory and models of film growth
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.05.030

Characteristics of carbon coatings on optical fibers prepared by radio-frequency plasma enhanced chemical vapor deposition with different H2/C2H2 ratios are investigated. Five kinds of carbon coatings are prepared with H2/C2H2 ratios of 2, 4, 6, 8, and 10. Experimental results show that the deposition rate and surface roughness of carbon coatings decrease as the H2/C2H2 ratio increases. When the H2/C2H2 ratio changes from 2 to 8, the increase of H2/C2H2 ratios detrimentally yields sp3 carbon atoms and sp3-CH3 bonds in the carbon coatings. However, when the H2/C2H2 ratio exceeds 8, the hydrogen retards the growth of the graphite structure. Moreover, the redundant hydrogen radicals favor bonding with the dangling bonds in the coating surface. Therefore, when the H2/C2H2 ratio increases from 8 to 10, the amounts of sp3 carbon atoms and sp3-CH3 bonds in the carbon coatings increase. At an H2/C2H2 ratio of 8, the carbon coating exhibits excellent water-repellency and thermal-loading resistance, and so this ratio is the best for producing a hermetically sealed optical fiber coating.