Long wavelength emission from nano-cone structures with embedded single InAs/InGaAlAs quantum dots grown on InP substrates

In this work we present a way to use high density quantum dots (QDs) as a possible source for single photons and entangled photon pairs by isolating a small number of dots in suitable nanostructures which, themselves, offer a favorable geometry and interface design for highly efficient luminescence extraction. InAs/InGaAlAs QDs grown on InP substrates are chosen as emitters in the spectral range between 1.2 and 1.6 μm. Low temperature luminescence from individual dots is shown in the spectral range between 1.3 and 1.4 μm. Emission in the longer wavelength range can be achieved by temperature tuning up to 160 K and changing the deposited amount of InAs (active QD layer) up to six monolayers. The accessible spectral range includes the telecommunication wavelength of 1.55 μm which makes such devices good candidates for application in fiber communication networks.