Growth and Optical Characterizations of InAs-QDs Emitting at 1[mu]m with a Broadband Spectrum for a Light Source for Biomedical Optical Coherence Tomography

Emission wavelengths of self-assembled InAs quantum dots (QDs) were controlled at around 1.05[mu]m by using the In-flush technique. A rapid annealing (In-flush) process after the growth of the GaAs capping layer, which partially covers the InAs-QDs, reduces the height of the InAs-QDs to the thickness of the capping layer. Using this technique, the emission wavelengths of the QDs were precisely controlled by varying the thickness of the capping GaAs layer. The central emission wavelength was suitably controlled in the range of approximately 0.95-1.22[mu]m. This method enables the realization of a broadband 1.05[mu]m light source with a bandwidth of beyond 200nm via a combination of In-flushed QDs. Such a broadband light source with a wavelength of 1.05[mu]m is applicable to optical coherence tomography (OCT), thereby enabling high resolution and large penetration depth in the OCT images. In addition, we have grown a sample including stacked layers of In-flushed QDs and obtained an emission spectrum with a central peak at 1.09[mu]m and a bandwidth beyond 100nm. These results suggest that an axial resolution of approximately 5[mu]m will be achieved by the use of the light source in OCT.