News

28.02.2016 - 16:54

Q.com article in the „Physik in unserer Zeit“

A recent open-access article by research partners from the BMBF Q.com Research Network project entitled "Sichere Kommunikation per Quantenrepeater" is published in "Physik in unserer Zeit", which reports on the current state and the main challenges in this field.

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12.12.2015 - 12:00

3rd OCL-TP Workshop

On 10-11th December, the 3rd International Workshop between the "Optical Communication Lab" and the Department "Technological Physics" took place under framework of long-term cooperation agreement between the Israel Institute of Technology and the University of Kassel.

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23.07.2015 - 16:54

OCL-TP Workshop

On 22-23rd July, the 2nd International Workshop between the "Optical Communication Lab" and the Department "Technological Physics" took place under framework of long-term cooperation agreement between the Israel Institute of Technology and the University of Kassel.

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Nano Optics

Group Members

Group Leader:  Mohamed Benyoucef
PhD Students:  Andrei Kors, Patrick Krawiec, Matusala Yacob, Muhammad Usman
   

Objectives

The research group focuses on the development of novel and advanced quantum architectures fabricated on Si, GaAs, (flat and pre-patterned) and InP substrates using molecular beam epitaxy and investigated their specific aspects of quantum optics. The first is considered to be as one of the key technologies combining the best of both materials leading to a highly versatile hybrid photonics platform which opens the way to large scale photonic integration; this could allow a direct combination of photonics and electronics on the same chip. The later could allow the implementation of efficient single-photon sources for long-distance quantum information.

 

The emphasis is on the fabrication (growth and processing) and studies the fundamental structural and quantum optical properties of the single quantum nano-architectures. Integration of III-V semiconductor light sources with silicon, fabrication and characterization of microcavities (e.g., photonic crystal) in combination with integrated quantum dots and processing of nanostructured surfaces for optical devices.

Projects

BMBF-Project "Q.com"

Research Activities

  • Epitaxy growth of semiconductor nanostructures on different substrates using MBE-system

  • Development of single-photon sources at telecom wavelengths for long-distance quantum communication

  • Development of telecom quantum dot emission for spin storage

  • Integration of single InA/GaAs core-shell quantum dots in silicon

  • Processing of nanostructured surfaces for the realization of deterministic optical devices

  • Fabrication and investigation of microcavity structures (e.g., pillar cavities, photonic crystals)

  • Studies the structural properties of self-assembled quantum dots

  • Studies light-matter interaction at the nanoscale of solid-state quantum systems

 

 InP-based quantum dots:

(a) µ-PL spectrum from single InP-based quantum dot (QD). The inset shows the 2x2 µm2 2D AFM image of low density QDs. (b) Single-photon emission at telecom wavelengths from single InP-based QDs (in cooperation with Uni. Stuttgart). (c) Coherent properties of single InP-based

(a) µ-PL spectrum from single InP-based quantum dot (QD). The inset shows the 2x2 µm2 2D AFM image of low density QDs. (b) Single-photon emission at telecom wavelengths from single InP-based QDs (in cooperation with Uni. Stuttgart). (c) Coherent properties of single InP-based QDs (in cooperation with Uni. Paderborn).  (d) The measured electron (full squares) and hole (open circles) g-factors for QDs emitting at telecom wavelengths (in cooperation with TU Dortmund). 

 
Literature:

 

 InP-based photonic crystal microcavities:


(a) μ-PL spectra of L3 PhC microcavity taken at 10 K (blue line) and 300 K (red line). Inset: high-resolution μ-PL spectrum of the fundamental mode M1with quality factor of 8700. (b) µ-PL spectra: black line without polarization, red line with horizontal polarization and blue line with vertical polarization. Insets: SEM image of the L3 PhC cavity and polar plot of cavity modes intensities as a function of polarization angle. (c) µ-PL spectra of a single QD, showing X and XX emission lines. (d) X and XX PL intensities as a function of laser excitation power. (e) X and XX transitions recorded at 0° (red) and 90°(black) polarization angles, showing vanishing fine-structure splitting.


Literature:


Silicon-based quantum dots:




Left: InAs QDs embedded in silicon matrix (in cooperation with PDI Berlin). Right: Light emission from single inAs/GaAs core-shell QDs directly grown on silicon.

Literature:

 

  GaAs-based quantum dots:


 

(a & b) Single-photon emission and X lifetime from single QD grown by droplet epitaxy (in cooperation with HU Berlin). (c) Quality
factor enhancement in coupled resonators (in cooperation with Uni. Magdeburg and IFW Dresden).

 

Literature:

 

   

Site-controlled quantum dots on pre-patterned GaAs and silicon substrates:


Left: Site-controlled QDs on GaAs substrates. Right: III-V nanostructures localized in the patterned silicon nanoholes.


  Literature:

 

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