High thermal conductivity composites for laser diode applications

Currently used laser diodes suffer from poor thermal management. Typically, Cu-W is used as a submount material. It offers a good CTE match with GaAs but its thermal conductivity is very limited (160 W/mK). Two approaches to improving the thermal performance of laser diodes were developed: i) the use of diamond-aluminum composites ii) the use of hybrid C-C/graphite foam composites A novel process was developed to address the interfacial problems in diamond composites. As a result isotropic diamond/Al composites exhibiting 600 W/mK were developed. Carbon-carbon composites offer good thermal performance but suffer from high anisotropy. In order to alleviate this problem hybrid 1-D C-C/graphite foam composites were developed. Graphite foam offers a good spreading angle while the 1-D C-C composite offers very good conduction towards the heat sink.