20.06.2018 - 13:00

7th OCL-TP Workshop

On 7-8th June, the 7th 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.


10.04.2018 - 12:00


Monolithic cointegration of QD-based InP on SiN as a versatile platform for the demonstration of high performance and low cost PIC transmitters (MOICANA)


28.02.2016 - 16:54 article in the „Physik in unserer Zeit“

A recent open-access article by research partners from the BMBF 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.


Nano Optics

Group Members

Group Leader:  Mohamed Benyoucef
PhD Students:  Andrei Kors, Patrick Krawiec, Matusala Yacob, Muhammad Usman
Master & Bachelor Students:  Birk Fritsch, Lucas Rickert, Adnan Sayyed, Andreas Körner


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.





Open Positions:

We are always interested in motivated and ambitious students, who are eager to embark on a challenging project with us (for Bachelor, Master and PhD level). Do not hesitate to contact me ( You are also very welcome to bring your own ideas and I will be happy to discuss it with you.

PostDoc and PhD positions:

In the framework of a BMBF project, a PhD position is available and to be offered to highly motivated student who intends to enhance her/his scientist carrier in the field of semiconductor quantum optics. She/he should have a high interest in basic experimental research and like working in an interdisciplinary environment. The research will be carried out in the Nano Optics group at the Institute of Nanostructure Technologies and Analytics, INA. The focus of the project is to grow, process (in clean room), characterize, and embed in resonators and pin-diode low density InP- based QDs. The final goal is to achieve high quality single QDs emitting around 1.55 µm for quantum information applications. The work will be performed in close collaboration with other project partners. For more information contact us (


In the framework of a LOEWE project, we inivite strongly motivated people to apply for research assistant positions (two PhD students and one PostDoc) to join their Nano Optics Group led by Priv.-Doz. Dr. M. Benyoucef as part of a new interdisciplinary project on Scalable Molecular Quantum Bits (SMolBits). 

See also the announcement for open position at

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). 



 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.


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.



  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).





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.



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