"Nanostructured InP Based Materials and Their Applications in Classical and Quantum Optical Communication Systems"

Professor Johann Peter Reithmaier, Institute of Nanostructure Technologies and Analytics (INA), University of Kassel, Germany

June 29th (Monday), 2:00pm
Engineering Science Building (ESB), Rm 2001

The talk will give a brief overview about the activities of our group at INA with a main focus on epitaxial growth of III-V quantum dot (QD) materials on InP using molecular beam epitaxy and in the realization of advanced optoelectronic devices based on nanostructured InP-based materials for classical optical communication systems (from long reach to on-chip) as well as for future quantum communication networks. In addition, an outlook will be given for a new optically active Si-based material for a next generation Si photonics platform.

Nanostructured optical gain materials have many advantages compared to the standard bulk or quantum film materials typically used in optoelectronics, e.g., much higher material gain, much faster intrinsic carrier dynamics, etc., with direct consequences for device properties, like low laser threshold current, higher temperature stability, reduced linewidth or multi-wavelength amplification. However, for many years QD materials suffered by an insufficient modal gain due to too large size inhomogeneity and too low QD density.

A few years ago new growth techniques for the growth on 1.55 μm QDs on InP material basis were developed, which tripled the modal gain of QD lasers and which can now fully compete in basic properties with quantum well lasers. Record values in digital modulation speed of 22 GBit/s could be obtained with 275 μm long 1.55 μm QD lasers. Similar QD material can be used to realize widely-tunable narrow-linewidth DFB lasers for coherent communication. Results will be shown giving a clear evidence for a strong linewidth reduction related to the quasi zero-dimensional character of the laser material.

For reducing power consumption in high-capacitance data networks all optical high-speed switching fabrics would be favorable to avoid high power consuming electro-optical conversions. Recent results on low-power (60 fJ/Bit) high-speed (6.5 ps) all-optical switches based on strongly coupled nanocavities and realized in InP photonic crystal membrane structures will be presented.
To establish future optical quantum networks on the basis of existing fiber networks, one of the key components are single or entangled photon sources emitting at 1.5 μm. For this purpose low-density quantum dot material on InP substrates were developed, with highly efficient narrow linewidth single photon emission.

A long ongoing dream in silicon based microelectronics and more recent nanophotonics is the integration of high-quality optically active components, like light sources, amplifiers and non-linear devices on Si chips. A lot of effort is focused on wafer fusion/bonding or flip-chip mounting techniques or on direct planar growth using thick relaxation layers. Unfortunately, none of these techniques are fully CMOS compatible and need separate III-V material processing.

Based on the recent progress to realize core-shell InAs/GaAs QDs with high optical quality directly grown on silicon surfaces, a radically new approach will be discussed for the realization of optically active silicon, which may allow the direct integration of III-V material in planar defect-free single crystal silicon matrix, and which can directly be processed with silicon technology.

About Professor Johann Peter Reithmaier:

photo of j.p.reithmaier Johann Peter Reithmaier studied Physics at TU Munich and made his PhD at Siemens Research Labs and Walter-Schottky-Institute in 1990. Until 1992, he worked as Postdoc at IBM in Rüschlikon, Switzerland on III/V epitaxy for high power and telecom lasers. In 1992, he joined University of Würzburg where he built up a research group working on nanostructured semiconductors and their applications in optoelectronic devices. He finished Habilitation in 1997 and became a faculty member of physics in Würzburg. In 2005 he became a full professor of physics and director of the Institute of Nanostructure Technologies and Analytics at the University of Kassel.

He is author or co-author of more than 600 publications (> 290 in ref. journals, > 100 invited talks, 7 book articles, 2 books). He was coordinator of several European projects and contributed to many national and international projects covering a wide range of research topics from material research to semiconductor devices, e.g., single photon sources, high power lasers and high-speed telecom lasers. He is a member of the Deutsche Physikalische Gesellschaft (DPG) and Fellow of IEEE. Since 2010, he is on the advisory board of the EPSRC National Centre for III-V Technologies in UK.

The main interest is focused on III-V nanostructured materials and optoelectronic or nanophotonic devices dedicated for applications in classical and quantum optical communication systems. This includes material research for new epitaxial materials (e.g. IIIV compound semiconductors or nano crystalline diamond on silicon), development of new nano fabrication technologies and optoelectronic devices (e.g., high-speed QD lasers, single photon emitters, all-optical nano photonic devices).

Hosted by: Alan Liu, Materials / ECE