<title>1x8 single-mode fused optical fiber couplers</title>

Abstract

We present various fabrication techniques for 1 by 8 single- mode fiber couplers. Single-mode couplers are used for signal distribution in optical networks. Traditionally, for division of eight or more, several couplers are cascaded. This constraints increases the length as well as the production cost of the component. Our work demonstrates that the fusion/stretching process for making couplers can be applied to couplers containing up to eight fibers. Three different techniques have been studied to produce these couplers. Through one technique, uniformity of power was obtained at 1.55 micrometers . Typical losses are less than 1 dB. A theoretical analysis of the structure shows the coupling of eight supermodes. However, if transversal symmetry is respected, only two of these supermodes will interact in the power transfer between the fibers. The control of the interaction of these two supermodes permits a control of the wavelength dependence of the component. These phenomena are analyzed and experimental results are presented. The new 1 by 8 coupler is a compact component of less than 10 cm that integrates itself efficiently within the networks.