Performance Evaluation Of Single-Mode Couplers

In an earlier paper we reported the development of a fusion technique for fabricating environmentally stable, single-mode couplers. During the past year we have fabricated couplers in a production environment and have studied the reliability of the coupler fabrication process. These couplers were designed to have a nominal coupling ratio of 50%. We found that a significant fraction exhibited excess losses of less than 0.05dB. Further, through the use of an automated test facility, we have investigated the performance of the couplers under varying ambient conditions. The test conditions included changes in temperature, variations in the polarization of the input light and variations in the wavelength of the source. In this paper we report the findings of our studies and discuss the implications with regard to the reliability of the fiber optic coupler. This data will allow the designer of a fiber optic system which utilizes single-mode couplers to predict the stability of that system in various environments.