Investigations on electro-optical and thermal performances degradation of high power density GaAs-based laser diode in vacuum environment

Pump laser diodes emitting at 980 nm are typically used in distribution network transmission systems and are now implemented in space missions for intra-satellite communication links and calibration systems. Nevertheless, since the pump source is potentially a critical point for such systems, there is a huge need to assess their reliability in space environment, especially in terms of operation under vacuum conditions. We have then studied the electro-optical behavior of several 980 nm laser diodes and shown that they may degrade more rapidly when submitted to a vacuum environment. Then, spatially resolved temperature variations have been measured by thermoreflectance on the laser diode front facet and have shown a temperature variation increase under vacuum conditions, in particular near the emission region, where a catastrophic optical damage is most likely to occur. This temperature variation increase could then be one of the causes for the more rapid laser diode degradation.