Preliminary results on high-total-dose testing of semiconductor photonic sources: a comparison of VCSELs and resonant-cavity LEDs

Low-power consumption, high efficiency and high bandwidth surface emitting semiconductor optical sources are critical elements in the development of future photonic systems for space and civil nuclear applications. In this paper, we report on preliminary high total dose experiments performed on two types of recently developed microcavity emitters: VCSELs and microcavity (or resonant cavity) LEDs. We gamma irradiated a total of twelve commercially available packaged VCSELs and two home-made flip-chipped 2 X 2 microcavity LED arrays. For doses between 5(DOT)106 Gy and 1.3(DOT)107 Gy the VCSELs show a threshold current increase lower than 20% and an output power decrease lower than 10%. These values are even smaller if the VCSEL is operated at a higher temperature. At a dose of 3.14(DOT)107 Gy, one VCSEL still showed satisfactory operation. The microcavity LEDs suffered from a burn-in after radiation but recovered quickly when biased. Their output power decrease is comparable to that of the VCSELs, while their quantum efficiency is not much affected. The specifications of both types of devices are not substantially altered by high gamma doses and can therefore be considered for application in enhanced radiation environments.