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Integrated-optical nanosystems based on II/VI semiconductors

The objective in this project is the development and realization of nanostructures from strained II-VI semiconductor quantum structures.

The effect of strain relaxation in microdisk cavities was studied by advanced micro-Raman spectroscopy and micro-photoluminescence spectroscopy. The results revealed a continuous release of strain along the radial direction of the microdisks and membranes without significant generation of misfit dislocations. Indeed, the inhomogeneous strain state of the free standing part of the microdisks for example, results in a lateral band profile that favours radial charge carrier transport from the centre to the edge of the disks where the resonator modes are localized. This effect allows for demonstration of microdisk lasers with extremely low threshold powers. We also try to integrate our fluorine single photon emitters into tailored microresonators and waveguide structures to increase the photon extraction efficiency and enable photon transfer between several microcavities for “scaling up” small quantum networks. Currently the waveguide properties of free-standing membranes coupled with microdisk cavities in an “all-on-the-chip” integrated-optical design are investigated.

Integrated Optics 1 Scanning electron microscope image of a set of waveguide-coupled microdisk cavities for efficient photon outcoupling.

Integrated Optics 2 Top view of one structure including microdisk, wave-guide and surface gratings.

Selected Publications in this topic:

“Lasing of donor bound excitons in ZnSe microdisks”, A. Pawlis, M. Panfilova, D.J. As and K. Lischka, K. Sanaka, T.D. Ladd, Y. Yamamoto, Phys. Rev. B 77, 153304 (2008).

“Microdisks of strain-compensated CdSe/ZnSe/(Zn,Mg)Se quantum wells for quantum communication”, M. Ruth, A. Finke, G. Schmidt, D. Reuter, S. Scholz, A. Ludwig, A.D. Wieck and A. Pawlis, Optics Express 23, 29079 (2015).