Systematic investigation of the influencing parameters of an external cavity laser with a quantum dot gain chip

Abstract

External cavity lasers show a variety of uses, for which quantum well semiconductor lasers are already commercially used. Due to the atom-like discrete energy levels, quantum dots exhibit various properties resulting from the three-dimensional confinement of carriers, like high stability against temperature variation, large gain bandwidth, and low-threshold lasing operation. Quantum dots seem to be ideal to address the challenges in the further development of various semiconductor applications, such as high-resolution spectroscopy or broadband optical communication networks, for which a range of spectral and temporal characteristics is required, for instance a narrow spectral linewidth, low intensity noise or wide wavelength tunability. In this view, external cavity quantum dot gain chips can be envisoned to replace the current quantum well technology. Using a semi-analytical rate equation model, we successfully analyze both dynamical and noise properties of an external cavity laser made with quantum dot gain medium, operating under strong optical feedback. This paper investigates the turn-on delay, the relative intensity noise, and the frequency noise and compares them to the case without optical feedback. These numerical investigations of an external cavity quantum dot gain chip provide meaningful building blocks for future fabrication research or for developing high performance device such as wavelength-selective components.