Evaluation of the Radiation Hardness of GaSbbased Laser Diodes for Space Applications
Ignacio Esquivias, José-Manuel G. Tijero, Juan Barbero, Demetrio López, Marc Fischer, Karl Roessner, and Johannes Koeth
Abstract—We present an evaluation of the effects of proton and gamma irradiation on the performance of GaSb-based 2.1 µm laser diodes lasers for space applications. The study is focused on the effects of radiation on the Power-Current, Current-Voltage and Wavelength-Current-Temperature characteristics of the lasers. No significant radiation damage has been found.
Index Terms— Laser diodes, GaSb-based materials, radiation effects, mid-infrared lasers.
I. INTRODUCTION ASER diodes are increasingly used for space applications, either to pump solid state lasers, in photonic payloads, or as sources for LIDAR or spectrometric applications. In space applications reliability issues are a primary concern and among them, radiation hardness is one of the most distinctive with respect to terrestrial applications. A good deal of effort has been devoted to study specifically the effect of radiation on the performance of the most common visible and near infrared emitting GaAs- and InPbased diode lasers [1-5, and references herein]. Johnston and Miyahira  studied the effect of proton radiation on different types of low power commercial laser diodes with emission wavelengths between 660 and 1550 nm. They found a linear increase of the threshold current with proton fluence as well as a small reduction of the slope efficiency. They interpreted the degradation as arising from an increased non-radiative recombination rate and observed more clearly the radiation effect when they measured the devices below threshold. Troupakia et al.  performed a detailed test plan for 808 nm high power laser bars including vibration test, proton and gamma irradiation. They concluded that the evaluated devices
Manuscript received April 29, 2011. This work was supported by the ESA under ITT AO/1-5618/08/NL/CP “Screening and Pre-evaluation of Shortwave Infrared Laser Diode for Space Application”. Ignacio Esquivias and José-Manuel G. Tijero are with Universidad Politécnica de Madrid, ETSI Telecomunicación, Ciudad Universitaria, 28040 Madrid (Spain), (phone: +34913367339; fax: +34913367319; e-mail: esquivia@ tfo.upm.es). Juan Barbero and Demetrio López are with Alter Technology Group Spain, Majada 3, 28760 Tres Cantos (Spain). Marc Fischer, Karl Roessner, and Johannes Koeth are with nanoplus GmbH, Nanosystems and Technologies, Oberer Kirschberg 4, D-97218 Gerbrunn (Germany) are robust enough to survive the vibration and radiation stresses of most space flight missions. However, as far as we know, the radiation effects on GaSbbased laser diodes have not been previously investigated. These devices, emitting in the middle infrared between 2 and 3 µm are of a great interest for spectroscopy applications.
The degradation of GaSb p-n junctions after irradiation has been analyzed in , in the frame of their application in multiplejunction solar cells. An increase of the non-radiative recombination after radiation was observed, and the degradation rates for GaSb and GaAs junctions were found to be similar in the order of magnitude. In this work we present results on the radiation hardness of mid infrared emitting GaSb-based diode lasers for space applications.
The work has been performed in the framework of the European Space Agency (ESA) Invitation to Tender AO/1-5618/08/NL/CP), with the aim of evaluating the future use of these devices in on-board spectrometric applications. The general results of the evaluation were presented in .