High power performances of broad bandwidths superluminescent diodes (SLDs) based on chirped-quantum-dot structures operating at 1100 and 1200 nm for optical coherence tomography (OCT) applications

New OCT systems demand higher resolution using broadband SLDs. This paper presents a new class of SLDs based on chirped multilayered quantum dots to achieve broad spectral widths. These SLD chips and modules operating around 1.1 mum and 1.2 mum have demonstrated wide optical spectra, low spectral ripples and dips allied with record output powers crucial for signal-to-noise performance for in vivo OCT imaging applications. The SLD samples are grown by molecular beam epitaxy on GaAs n+ substrates. The quantum dot (QD) active region is grown within a GaAs-AlGaAs waveguide designed to reduce series resistance whilst retaining a useable far field characteristic. SLD structures comprise 5 to 6 mm long, 7deg tilted single mode ridge waveguide. Both facets are antireflection coated. Regarding chirped QD-SLD behaviour under a continuous injection current increase, a rapid decrease of the first GS with a simultaneous increase in intensity of the first ES at a certain level is observed, the latter staying constant until the enhancement of the second ES achieves equal power between both at the saturation power.