Monomode Optical Waveguide Connectors

Abstract

The problems to be discussed all fall into the category of guided-wave optical coupling between separate guiding structures. Various types of structure need to be connected: single mode circular optical fibres, laser diode chips, thin-film (‘integrated’) optical waveguides, photodetectors. Certain combinations are clearly of greater importance than others, and in particular minimum losses are required of fibre-fibre connections to be used in long-distance high-capacity fibre communication links, in which a number of connections per link must be made. In other situations criteria of success may well be different; thus in a similar link the important factor at the laser diode fibre connection may well be the power reflected back into the laser junction by the fibre input face, which can nave an adverse effect on the operation of the laser. Because only one such connection is incorporated in each fibre link, the associated connection loss is of secondary importance. Reflections may also be undesirable in some of the measurement applications of guided-wave optics, particularly those depending on the interference between two phase-modulated signals, such as in the fibre gyroscope.