Spectral Hole Burning Spectroscopy on Quantum Dashes and Quantum Dots for Dual-Frequency Laser Engineering

The homogeneous linewidth of two inhomogeneous media is investigated by Spectral Hole Burning in resonant excitation conditions for the purpose of dual-frequency VECSEL engineering. We performed Spectral Hole Burning experiments on InAs/InP Quantum Dashes and Quantum Dots, as well as on InGaAs/InP Quantum Wells to get a reference of homogeneous behavior. Experimental evidences show that Quantum Dots having different energies inside the whole QD population are less coupled than Quantum Dashes. At a low temperature of 77K, the homogeneous linewidth is only 0.73 meV for QDs versus 1.17 meV for QDashes. With increasing temperature, electronic coupling between the dots populates nanostructures at other energies than the excitation energy. However, a resonantly excited QD population remains visible up to 130 K, a larger temperature than for QDashes, and even at room temperature a signature of the excitation energy remains visible in the Spectral Hole Burning spectra.