Broadband emission centered at ∼1 µm with a Gaussian-like spectrum by stacking In-flushed QD layers



We have grown a stack of In-flushed InAs quantum dot (QD) layers to realize a broadband emission centered at ∼1 µm with a Gaussian-like spectrum as a light source for optical coherence tomography (OCT). The In-flush process, which enables control of the height of the QD, was optimized to control the emission wavelength and intensity of self-assembled InAs/GaAs QDs. A partial capping layer of GaAs was deposited on as-grown InAs/GaAs QDs with various thicknesses (dcap), and a rapid annealing of the sample was executed with the proper annealing temperature. By optimizing dcap and the annealing temperature for each QD layer, a broadband Gaussian-like spectrum with a 102-nm-bandwidth was obtained. The coherence function of the emission spectrum exhibits a 4.5-µm axial resolution for OCT images without distinct side lobes. These results demonstrate the effectiveness of the In-flushed QDs as a light source to obtain high-quality OCT images. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)