Optical spectroscopy and modelling of double-cap grown InAs/InP quantum dots with long wavelength emission

We report on an optical study of InAs quantum dots grown on an InP(311)B substrate, and lasing at 1.55 mum wavelength. A new growth technique, called the 'double-cap' technique, has been used to reach 1.55 mum at 300 K. The samples are characterized at low temperature and room temperature by continuous-wave and time-resolved photoluminescence techniques. The wetting layer emission and a dot excited state emission are clearly observed for the first time in this kind of dot, and the results are consistent with theoretical calculations. At the same time, these structures seem to have a better capture efficiency.