Characterisation of III-V optoelectronic devices by Internal Second-Harmonic Generation technique

A surface characterization technique based on the Internal Second-Harmonic Generation (SHG) in optoelectronic devices has been used to study the mirro r degradation of 1.55 mu m semiconductor optical amplifiers (SOAs) exposed to an antireflection coating deposition technique and 980 nm pump lasers su ffering from mirror oxidation during life-tests. In both cases, an overall increase in SH emission was observed, as a consequence of mechanical stress enhancement and defects formation due to oxidation phenomena occurring at the interface between semiconductor and coating film. In the case of pump l asers, an oscillating, periodic trend superimposed to the general increasin g one was also observed and interpreted as the periodic relaxation of compr essive strain in the active layer due to vacancies formation in the near-mi rror semiconductor layer. (C) 1999 Elsevier Science B.V. All rights reserve d.