Optogenetics is a breakthrough neurostimulation technology which enables precise optical control over the function of neurons that have been genetically engineered to feature light sensitive opsin proteins. The light source is typically placed externally and light is guided in via optical fibres. This has advantageous but comes at the disadvantage of needing a permanent hole in the blood brain barrier so efforts to fully implant the light source, with wireless communication and power are needed. Here we present a multi-parametric finite element analysis of the heat distribution generated by typical microLED for optical implants, encapsulated by a biocompatible polymers.