Plenarvorträge - DPG-Tagungen

Halbleiterphysik Dienstag
HL 15 Photonische Kristalle III
Zeit: Dienstag 10:15–13:30 Raum: H17
HL 15.1 Di 10:15 H17
Dye functionalization of living photonic crystals — •Thomas
Fuhrmann, Stefan Landwehr, and Melanie El Rharbi-Kucki
— Makromolekulare Chemie und Molekulare Materialien, Fachbereich
Naturwissenschaften und Center for Interdisciplinary Nanostructure Science
and Technology, Universität Kassel
Biological structures offer a convenient way for producing photonic
crystals. The silica cell wall of centric diatoms can be regarded as hexagonal
and quadratic slab waveguide photonic crystals with partial bandgaps
in the visible spectral range. In order to address the question how absorption
and emission of light is influenced in these structures, organic dyes
have to implemented into the cell wall. We demonstrate some techniques
of dye functionalization with laser dyes, including a chemical as well as
a biological approach. This project is part of the DFG priority program
on photonic crystals.
HL 15.2 Di 10:30 H17
Periodically Arranged Point Defects in a Two Dimensional
Photonic Crystal — •Stefan Richter 1 , Stefan Schweizer 2 , Cecile
Jamois 1 , Reinald Hillebrand 1 , Nikolai Gaponik 3 , Andrey
Rogach 4 , Ralf Wehrspohn 2 , and Margit Zacharias 1 — 1 Max-
Planck-Institut für Mikrostrukturphysik — 2 Universität Paderborn —
3 Universität Hamburg — 4 Ludwig-Maximilians-Universtität München
We present and charcterize hexagonal point defects in a two dimensional
photonic crystal based on macroporous silicon. These point defects
are prepatterned periodically, forming a superstructure within the
photonic crystal after electrochemical etching. Spatially resolved, optical
investigations related to morphological properties, like defect concentration
and pore radius, are compared to bandstructure calculations. The
confined defect states are identified and their interaction is evaluated
quantitatively. To investigate the influence of the cavity on internal light
emitters, colloidal HgTe quantum dots have been infiltrated into single
cavities and their emission was measured by photoluminescence.
HL 15.3 Di 10:45 H17
Tunable Photonic Crystal circuits: Novel concepts and designs
— •Matthias Schillinger 1 , Sergei Mingaleev 1,2 , Daniel Hermann
1 , and Kurt Busch 1,3 — 1 Institut für Theorie der Kondensierten
Materie — 2 Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine
— 3 School of Optics/CREOL and University of Central Florida, Department
of Physics, Orlando, USA
Over the past years, substantial research efforts have been directed at
investigations of Photonic Crystals (PCs) with embedded defects such
as microcavities and waveguides. These structures hold tremendous potential
for the creation of very compact all-optical photonic integrated
circuits which are required for the next generation of high-throughput
optical communications systems.
In this talk, we suggest that tunable PC circuits can be created by
infiltrating individual pores of bulk 2D PCs such as macroporous silicon,
with liquid crystals or polymers. We show that a row of infiltrated
pores can be used as a single-mode PC waveguide, and demonstrate very
efficient broad-band transmission through sharp waveguide bends. For
infiltration with liquid crystals, we illustrate different types of tunability
of PC circuits. Such functional elements can be designed accurately and
efficiently through a Wannier function approach [1] in combination with
the guided-mode scattering matrix approach [2].
[1] K. Busch et al., J. Phys.: Condens. Matter 15, R1233-R1256 (2003)
[2] S.F. Mingaleev and K. Busch, Opt. Lett. 28, 619-621 (2003)
HL 15.4 Di 11:00 H17
Photonic crystals with complete three-dimensional bandgap in
macoporous silicon — •Sven Matthias 1 , Frank Müller 1 , Cécile
Jamois 1 , Ralf B. Wehrspohn 2 , and Ulrich Gösele 1 — 1 Max
Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany
— 2 Department of Physics, University Paderborn, Warburger Str.
100, Paderborn 33098, Germany
Photonic crystals – artificial structures with periodic refractive index
variations – are the ”semiconductors” for the electro-magnetic wave propagation.
Suppression of spontaneous emission or loss-less waveguiding via
line defects in three-dimensional photonic bandgap materials are some
of the fascinating potential applications. Here, we describe the fabrica-
tion of a three-dimensional photonic crystal of overlapping air-spheres
in silicon in a simple cubic lattice. Our inexpensive and fast fabrication
method combines the advantages of the high accuracy of standard
photolithography with a large area three-dimensional etching process. 20
lattice constants in depth and thousands lateral lattice constants with
sharply modulated pores were grown and widened to obtain overlapping
air-spheres in silicon. We observed the optical properties in reflection
and transmission experiments along various crystal axes. They agree
well with bandstructure calculations. Together with the scanning electron
micrographs these are strong indications for a realised complete
three-dimensional photonic bandgap of about 3 % centred at 3 microns.
The large area of our structure and the variability in design enable for
all-optical microchips-approaches.
HL 15.5 Di 11:15 H17
Low loss GaAs based photonic crystal waveguides — •Helmut
Scherer1 , Martin Kamp1 , Stefan Deubert1 , Hans-Peter Reithmaier1
, Alfred Forchel1 und Reinhard März2 — 1Technische Physik, Am Hubland, D-97074 Würzburg — 2Infineon Technologies AG,
Corporate Research, D-81730 München
Photonic crystal (PhC) waveguides are important building blocks for
more complex PhC based devices. An important parameter, especially
for passive devices, is the loss of the waveguides. We have investigated
the loss of GaAs based photonic crystals at a wavelength of 1.3 µm.
The crystals are realized by an hexagonal array of air holes etched into
a GaAs/AlGaAs slab waveguide. Electron beam lithography is used to
define the PhC pattern in a resist layer, which is then used to pattern
an intermediate SiO2 mask. The holes are etched into the semiconductor
with an Cl2/Ar based ECR/RIE process. Holes with smooth sidewalls
and a depth of 1 µm are achieved. Measurements of the waveguide losses
are performed with an external tunable laser source covering a wavelength
range between 1240 and 1340 nm. The losses are determined from the
contrast of the Fabry-Perot resonances of the cavity formed by the two
cleaved facets and the PhC waveguide. This technique is not sensitive to
the coupling efficiency and therefore suitable for PhC waveguides, where
efficient coupling to an external source is often a concern. Comparing the
losses of waveguides with different lengths, it is possible to extract the
waveguide loss per length. The losses of the fundamental mode are about
5.1 db for W3-waveguides (3 rows missing in the PhC lattice) and about
for W5-waveguides.
mm
2.5 db
mm
HL 15.6 Di 11:30 H17
Photonic Molecule Formation in Microsphere Ensembles
Doped With Quantum Dots — •Björn M. Möller 1 , Mikhail
V. Artemyev 1 , Reinhold Wannemacher 2 , and Ulrike Woggon 1
— 1 Universität Dortmund — 2 Universität Leipzig
Semiconductor nanocrystals in spherical microcavities represent a
promising material system for the development of thresholdless lasers
and studies of light-matter-interaction regimes [1].
In this work, we report on the experimental observation of coherent
cavity field coupling in ensembles of spherical poystyrene microcavities
doped with CdSe quantum dots. The spatial dependence and polarization
nature of both the unperturbed cavity fields and the coupled binding
resonances are studied spectrally resolved in various one- and twodimensional
multisphere geometries. A mode mapping analysis [2] clearly
reveals the symmetry properties of the agglomerates for both types of resonances
and offers a detailed view of the optical confinement in sphere
based photonic molecules impregnated with nanoemitters.
The financial commitment of the DFG (SPP 1113) is gratefully acknowledged.
[1] U. Woggon et al., J. Appl. Phys. B 77, (2003)
[2] B. Möller et al., Appl. Phys. Lett. 83, (2003)