Optoelectronic packaging for fiber optic devices

Since the emergence and deployment of the first fiber optic networks in the late 1970s, the manufacture of active and passive components has given rise to a variety of packaging strategies.

As in microelectronics, packaging has the triple function of protecting the component, dissipating heat and interconnecting with the external environment. The particularity of optoelectronics lies in the management of optical inputs and outputs, which adds to package design the problem of coupling optical power into optical fibers, and the stability of this coupling as a function of the environment (temperature, humidity, vibration, etc.). These constraints gave rise to a number of original strategies which, in the 1990s, led to quasi-standard designs (Butterfly, coaxial, etc.).

Governed by the classical laws of electromagnetics, optical coupling is addressed by a limited number of designs. However, packaging solutions, which for a long time were reserved exclusively for telecom applications and therefore required high levels of reliability, have used relatively costly technologies (e.g. Kovar ^TM ). For example, the cost of packaging (materials and assembly time) accounts for 80% of the final cost of a telecom laser emission module.

The democratization of Local Area Networks (LANs) at company or even subscriber level since the 2000s has paved the way for new cost-effective packaging solutions based on emerging technologies, which will be discussed at the end of this article. These technologies, most of which have their origins in microelectronics, should eventually make it possible to achieve costs similar to those of microelectronics, i.e. around 20% of the cost of a component. This trend is confirmed by the deployment of short-distance optical links (active cables, peripheral connections) and the emergence of integrated optics technologies (on silicon, for example).

In this article, we describe the technologies needed to build optoelectronic modules for fiber gratings, as well as some of the design rules used by designers. We also mention the more recent technological developments required for emerging applications, notably linked to the emergence of integrated optics components. These developments take place within a normative framework briefly described at the beginning of the article...