High-resolution optical coherence tomography using broadband light source with strain-controlled InAs/GaAs quantum dots

Recently, there has been an increasing interest in broad-band light sources to develop a biomolecular imaging technique called optical coherence tomography (OCT). We fabricated superluminescent diodes (SLDs) using three kinds of quantum dot (QD) layers with different emission wavelength in the active region. The emission wavelength was controlled by reducing the strain in QDs by using In0.1Ga0.9As strain-reducing layer. The SLD device showed a broad electroluminescence spectrum with the center wavelength of 1104 nm and the spectral line-width of 122 nm at the injection of 40 mA, which corresponds to the theoretical axial resolution of 4.4 mu m. To estimate the actual resolution of the OCT system using fabricated SLD, we measured the interference signal in the Michelson interferometer. An axial resolution of 5.4 mu m, which is close to the theoretical limit, was obtained. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim