Tunable external cavity laser diode based on wavelength controlled self-assembled InAs quantum dots for swept-source optical coherence tomography applications at 1100 nm wavelength band

摘要

We fabricated and characterized a grating-coupled external cavity laser with gain chips including self-assembled InAsquantum dots (QDs) for swept-source optical coherence tomography applications. By controlling the emissionwavelength of the self-assembled InAs QDs, tunable lasing at a wavelength band of 1–1.1 μm was obtained, whichrepresents an optimal balance between absorption and scattering in biological tissues. Straight and J-shaped edgeemittingridge waveguides (RWGs) were fabricated on a GaAs-based waveguide layer containing four InAs QDs layers.A diffraction grating with the quasi-Littrow configuration was employed as an external cavity for the fiber-coupleddiodes. Electroluminescence spectra from the QD-based diodes revealed that broadband amplified spontaneousemissions appeared in a J-shaped RWG, whereas Fabry–Perot lasing occurred in the straight RWG. The external cavitywas then introduced for the diode with a J-shaped RWG, and a tuning range of 65 nm centered at approximately 1100nm was obtained from the QD gain chip with the J-shaped RWG.