[Seminar] WIGNER SZFI Seminar, 13 September - Balint Nafradi

[Janos Asboth]

*WIGNER SZFI Seminar*
*Hybrid Halide Perovskite: A game changer for telecommunication?*

*Bálint Náfrádi*
Laboratory of Physics of Complex Matter, Ecole Polytechnique Fédérale de
Lausanne (EPFL), CH-1015  Lausanne, Switzerland (host: Kamarás Katalin)

Thursday, 13 September 2018 10:00, KFKI Campus, Bldg. 1, 2nd floor,
Conference Room

Mostly fuelled by the increasing data hunger of social media, the internet
of things (IoT), and big data there is a continuous effort to push the
speed of wireless telecommunication. On fundamental thermodynamic grounds,
Shannon showed that for a given average signal power the channel bandwidth
limits the maximum attainable data rate. There are thus two ways to enhance
data speeds.
The first is to extend the bandwidth. To support this effort, terahertz
frequency band, 0.1-10 THz, is envisioned to be utilized for wireless
communication networks beyond 5G. Communication in the THz band is expected
to feature a number of attractive properties, e.g., Terabit-per-second
links, miniature transceivers, and high energy efficiency. However, a key
component for a communication link, the spatial THz-wave modulator, that
should actively control spatial transmission, reflection and polarization,
is missing. In the first part of my talk I will present an all-optical
approach to actively modulate electromagnetic waves from 0.1 THz up to 0.5
THz by magnetic photoconductors. Using low-fluence (< 20 μW/cm2) red light
illumination to optically melt the ferromagnetism of the magnetic
photocondutor CH3NH3(Pb:Mn)I3, we control the THz wave optical properties.
The amplitude of THz waves is modulated by up to 30% while the phase
rotates 60%. The amplitude and phase of the modulation is tuneable by the
light intensity as a control parameter. Our method provides a very simple
and energy-efficient technique for amplitude and phase modulation, and it
opens the way for a new family of spatial light modulator components.
The second approach to push the communication speed is to enhance the
detection efficiency of the photons carrying the information, to the
detection of single photons, the ultimate limit in detector sensitivity.
The availability of high-performance photon counters is crucial to
continued progress in the fields of quantum information processing and
quantum communication. In the second part of my talk, I will present a
novel microwave-read few-photon counter with CH3NH3PbI3 photoconductor as
an optically active element.



Everyone is welcome to attend.

János Asbóth
szfi-seminar at wigner.mta.hu
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