Optical assemblies for high performance and reliability in telecom and datacom applications have traditionally been implemented in hermetically sealed components. This is to protect the normally sensitive laser and photodiode devices from environmental conditions. The Telcordia GR-468 has long been the standard by which such hermetic devices have been tested against, for things such as high temperature storage, humidity, thermal cycling, etc. Recently, there has been increased interest in reducing the packaging cost of optics, as the number of high speed 10G/40G/100G datalink deployments grows at a rapid pace.
Cosemi has uniquely engineered the actual semiconductor device coatings (passivation, etc.) on our photodiodes to enable the die themselves to act as the hermetic seal against the typical GR-468 type of environments. Extensive environmental testing, including the standard 85C, 85% humidity exposure for over 500 hours, has been applied to these new photodiodes – with great success. We have trademarked this type of protective coating on the photodiode devices as Die Level Hermeticity (DLH) TechnologyTM.