Electrically Driven Near-Infrared Broadband Light Source with Gaussian-Like Spectral Shape Based on Multiple InAs Quantum Dots

Takuma YASUDA  Nobuhiko OZAKI  Hiroshi SHIBATA  Shunsuke OHKOUCHI  Naoki IKEDA  Hirotaka OHSATO  Eiichiro WATANABE  Yoshimasa SUGIMOTO  Richard A. HOGG  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.3   pp.381-384
Publication Date: 2016/03/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.381
Type of Manuscript: BRIEF PAPER
self-assembled InAs quantum dots,  molecular beam epitaxy,  broadband light source,  optical coherence tomography,  superluminescent diode,  

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We developed an electrically driven near-infrared broadband light source based on self-assembled InAs quantum dots (QDs). By combining emissions from four InAs QD ensembles with controlled emission center wavelengths, electro-luminescence (EL) with a Gaussian-like spectral shape and approximately 85-nm bandwidth was obtained. The peak wavelength of the EL was blue-shifted from approximately 1230 to 1200 nm with increased injection current density (J). This was due to the state-filling effect: sequential filling of the discrete QD electron/hole states by supplied carriers from lower (ground state; GS) to higher (excited state; ES) energy states. The EL intensities of the ES and GS emissions exhibited different J dependence, also because of the state-filling effect. The point-spread function (PSF) deduced from the Fourier-transformed EL spectrum exhibited a peak without apparent side lobes. The half width at half maximum of the PSF was 6.5 µm, which corresponds to the estimated axial resolution of the optical coherence tomography (OCT) image obtained with this light source. These results demonstrate the effectiveness of the QD-based device for realizing noise-reduced high-resolution OCT.