Non‐hermetic Encapsulation and Assembly Techniques for Optoelectronic Applications

The drive towards low unit cost in optoelectronic packaging is assisted by avoiding the need for hermeticity and by the use of simple assembly techniques. Silicone gels can solve this problem, provided the reliability meets the application requirements. Extensive lifetest data for semiconductor lasers and PIN photodiodes coated in silicone gels are reported in this paper. Results to date show great promise and promote confidence in the use of these materials for the environmental protection of optoelectronic devices. Apart from silicone gels, light cured resin materials can also offer benefits towards lower cost assembly processes. Tests are reported of the degradation in optical transmission of these resins and also bulk degradation under differing environmental conditions. The use of these polymer materials can play an integral part in low‐cost optoelectronic packaging developments, two specific designs of which — a silicon laser optical bench and a ceramic ferrule co‐axial structure — will be described. Both of these packages take advantage of a passive fibre/device alignment allowed by the use of an expanded beam laser design.