[OPTICAL REVIEW Vol. 6, No. 1 (1999) 77-81]
Direct Monitoring of Thickness and Refractive Index of Optical Thin Film Deposited on Fiber End-face
Yoshio SUZUKI,1 Shinji NAGAOKA1 and *Yuji UENISHI2
1NTT Opto-electronics Laboratories, 2NTT Affiliated Business Headquarters, 3-9-11, Midori-cho, Musashino, Tokyo 180-8585 Japan
(Received August 17, 1998; Accepted November 4, 1998)
We propose a system for depositing thin films on waveguides which enables low-temperature deposition and precise control of the refractive index and film thickness. It is composed of a conventional ion-beam sputtering (IBS) system and a new system for directly monitoring film characteristics during deposition. We controlled refractive indices over a wide range from 1.52 to 1.97 by moving the sputtering targets (SiO2 and Si3N4) in the IBS system. The refractive index or film thickness was in-situ monitored by observing the optical power reflected from the end-face of a monitoring fiber set in the deposition chamber. Antireflection coating films were successfully deposited on a fiber end-face and a laser diode chip facet with low reflectivity from 0.05 to 0.07%. This deposition system is attractive for constructing highly functional optical devices for future photonic networks.
Key words : ion-beam sputtering, antireflection coating, direct monitoring, optical thin film, dual targets