Effects of radio-frequency powers on the properties of carbon coatings on optical fibers prepared by plasma enhanced chemical vapor deposition

The effect of radio-frequency powers on the properties of carbon coatings on optical fibers prepared by plasma enhanced chemical vapor deposition is investigated. The radio-frequency powers are selected at 150, 200, 250, 300, and 350 W. Results indicate that if the radio-frequency power increases from 150 to 350 W, the deposition rate of carbon coatings and carbon grain size increase. As the radio-frequency power changes from 150 to 200 W, the water contact angle of carbon coatings increases due to the increase of sp3-CHx bonding. Alternatively, as the radio-frequency power increases from 200 to 350 W, the water contact angle of carbon coatings gradually reduces which is resulted from the increase of surface roughness. As the radio-frequency power is 200 W, the carbon coating has the highest water-repellency and the excellent ability to sustain the low-temperature loading, so it is the best for production of the hermetic optical fiber coating.