Thermal control is provided for external light sources for silicon photonics based pluggable modules. In one embodiment, an apparatus comprises a first circuit board; a light source disposed upon the first circuit board; a silicon photonics modulator; a connector comprising a first portion and a second portion, wherein: the first and second portions are physically matable and separable; mating the first and second portions of the connector optically couples the first and second portions, the first portion is disposed upon the first circuit board, and is optically coupled to an output of the light source, and the second portion is optically coupled to an input of the silicon photonics modulator; and a thermal controller to control a temperature of the light source. Some embodiments disable the light source when the connector is separated.