Reliability Considerations in Discrete Optics External Cavity Tunable Laser Assemblies

High coherence telecom systems and more recently data center applications require tunable external cavity lasers with very narrow linewidth and reliability over whole device lifetime. Tunability by using Liquid Crystal on Silicon component is a desirable approach with no moving part, able to grant linewidth lower than 100 KHz and Telcordia qualifiable devices. The use of subassemblies built up in parallel, together with a cheap glue-based fixing technique is attractive due to its orientation towards high volume industrial production. The issue of incomplete glue cross-linking when using curing temperatures lower than liquid crystal clearing temperature is demonstrated through a low-cost experimental approach, and a solution is given, sustained by Avrami-Erofe'ev kinetic model.