Milan Calic

Photonic-crystal microcavity laser with site-controlled quantum-wire active medium

Site-controlled quantum-wire photonic-crystal microcavity laser is experimentally demonstrated using optical pumping. The single-mode lasing and threshold are established based on the transient laser response, linewidth narrowing, and the details of the non-linear power input-output characteristics. Average-power threshold as low as approximately 240 nW (absorbed power) and spontaneous emission coupling coefficient beta approximately 0.3 are derived.

Bound and anti-bound biexciton in site-controlled pyramidal GaInAs/GaAs quantum dots

We present a detailed study of biexciton complexes formed in single, site-controlled pyramidal GaInAs/GaAs quantum dots (QDs). By using power dependent measurements and photon correlation spectroscopy, we identify the excitonic transitions of a large number of pyramidal QDs, exhibiting both positive and negative biexciton binding energies. Separation of charges within the QD, caused by piezoelectric fields, is believed to be responsible for the positive to negative crossover of the biexciton binding energy with increasing QD size. In particular, QDs exhibiting vanishing biexciton binding energies are evidenced, with potential applications in quantum information processing.

Site-controlled quantum dots coupled to a photonic crystal molecule

Two site-controlled quantum dots (QDs) were integrated in a photonic crystal molecule (PCM) formed by L3 nanocavities. A statistical analysis of the coupled cavity modes demonstrated the formation of bonding and anti-bonding delocalized PCM states. Excitonic transitions belonging to each QD were identified by scanning micro-photoluminescence spectroscopy. Co-polarization of the QDs photoluminescence with the coupled cavity modes provides evidence for the simultaneous coupling of two spatially separated QDs to the same PCM mode.

Effect of Pure Dephasing and Phonon Scattering on the Coupling of Semiconductor Quantum Dots to Optical Cavities

We investigate the effect of decoherence mechanisms in semiconductor quantum dot-cavity systems by performing photoluminescence measurements of InGaAs/GaAs site-controlled quantum dots coupled to photonic crystal cavities and comparing the results to a theoretical model.

1D and 2D arrays of coupled photonic crystal cavities with a site-controlled quantum wire light source

We investigated experimentally 1D and 2D arrays of coupled L3 photonic crystal cavities. The optical modes of the coupled cavity arrays are fed by a site-controlled quantum wire light source. By performing photoluminescence measurements and relying on near-field calculation of the cavitiy modes, we evidence optical coupling between the cavities as well as supermode delocalization. In particular, for small cavity separations, fabrication induced disorder effects are shown to be negligible compared to optical coupling between cavities.

Deterministic radiative coupling of two semiconductor quantum dots to the optical mode of a photonic crystal nanocavity

A system of two site-controlled semiconductor quantum dots (QDs) is deterministically integrated with a photonic crystal membrane nano-cavity. The two QDs are identified via their reproducible emission spectral features, and their coupling to the fundamental cavity mode is established by emission co-polarization and cavity feeding features. A theoretical model accounting for phonon interaction and pure dephasing reproduces the observed results and permits extraction of the light-matter coupling constant for this system. The demonstrated approach offers a platform for scaling up the integration of QD systems and nano-photonic elements for integrated quantum photonics applications.

Effect of pure dephasing and phonon scattering on the coupling of semiconductor quantum dots to optical cavities

We investigate the effect of decoherence mechanisms in semiconductor quantum dot-cavity systems by performing photoluminescence measurements of InGaAs/GaAs site-controlled quantum dots coupled to photonic crystal cavities and comparing the results to a theoretical model.

Phonon-mediated exciton-photon coupling in site-controlled quantum-dot-nanocavity systems

We show that far off-resonance exciton-photon coupling reported for self-assembled quantum dots in optical microcavities is not universal, and demonstrate that site-controlled dots exhibit clean phonon-mediated resonant coupling.

Active Semiconductor Nanophotonics based on Deterministic Quantum Wire and Dot Systems

We investigate the use of MOVPE-grown ordered nanostructures on non-planar substrates for quantum nano-photonics and quantum electrodynamics-based applications. The mastering of surface adatom fluxes on patterned GaAs substrates allows for forming nanostrucutres confining well-defined charge carrier states. An example given is the formation of quantum dot (QD) molecules tunneled-coupled by quantum wires (QWRs), in which both electron and hole states are hybridized. In addition, it is shown that the high degree of symmetry of QDs grown on patterned (111)B substrates makes them efficient entangled-photons emitters. Thanks to the optimal control over their position and emission wavelength, the fabricated nanostructures can be efficiently coupled to photonic nano-cavities. Low-threshold, optically pumped QWR laser incorporating photonic crystal (PhC) membrane cavities are demonstrated. Moreover, phononmediated coupling of QD exciton states to PhC cavities is observed. This approach should be useful for integrating more complex systems of QWRs and QDs for forming a variety of active nano-photonic structures.

Site-controlled quantum-wire and quantum-dot photonic-crystal microcavity lasers

Based on site- and energy-controlled quantum wires (QWR) and quantum dots (QD), diverse photonic-crystal microcavity laser systems are proposed and discussed. Results demonstrating QWR lasing, cavity coupling and QD ordered arrays are presented.