Optical probes as tools for the investigation of aging properties of high-power laser diode arrays

摘要

Abstract: Optical probes are used for the investigation of aging properties of high-power laser diode arrays. Two methods - micro-Raman and laser beam induced current (LBIC) scans are discussed: Micro-Raman spectroscopy - a laboratory based method - was applied in order to investigate facet temperature distributions for fresh and aged high-power laser diode arrays (LDA) under regular operation conditions. Furthermore, facet temperatures were measured for operation close to the catastrophic optical damage (COD) level.For these experimental situation facet temperatures of more than 600 degrees C were obtained. In order to conclude from pure temperature data to the thermal management of the LDA we performed modeling work based on the finite element method. Close to the COD up to 14 percent of the total thermal load of the LDA is concentrated to a very thin region close to the facet. Photocurrent spectra and LBIC were found to indicate aging induced effects such as defect creation as well as strain effects. LBIC - method which also could be used as test method for fabrication processes - allows to map aging induced changes of defect distributions in LDAs. Furthermore, the potential of LBIC as quick strain inspection method is discussed. !24