On one hand, interest on the tunability of the optical microcavities has increased in the last few years due to the need for selective nano- and microscale light sources to be used as photonic building blocks in several applications. On the other, transparent conductive oxide (TCO) β-Ga2O3 is attracting attention in the optoelectronics area due to its ultra wide band gap and high breakdown field. However, at the micro- and nanoscale there are still some challenges to face up, namely the control and tuning of the optical and electrical properties of this oxide. In this work, Cr doped Ga2O3 elongated microwires are grown using the vapor-solid (VS) mechanism. Focused Ion Beam (FIB) etching forms Distributed Bragg Reflector (DBR)-based resonant microcavities. Room temperature microphotoluminescence (μ-PL) spectra show strong modulations in the red-NIR range on five cavities with different lengths. Selectivity of the peak wavelengths is obtained, proving the tunability of this kind of optical systems. The confined modes are analyzed experimentally, analytically and via finite difference time domain (FDTD) simulations. Experimental reflectivities up to 78% are observed.
The Meteosat Third Generation (MTG) Programme is being realised through the well established and successful Cooperation between EUMETSAT and ESA. It will ensure the future continuity of MSG with the capabilities to enhance nowcasting, global and regional numerical weather prediction, climate and atmospheric chemistry monitoring data from Geostationary Orbit.
We report progress in the design of the BepiColombo Mercury Imaging X-ray Spectrometer (MIXS). This instrument
consists of two modules; a Wolter I soft X-ray telescope based on radially packed microchannel plate
optics (MIXS-T) and a profiled collimator which uses a square pore square packed microchannel plate array to
restrict its field of view (MIXS-C). Both instrument modules have identical focal planes (DEPFET macropixel
array) providing an energy resolution of better than 200 eV FWHM throughout the mission.
The primary science goal of MIXS is to perform X-ray fluorescence spectroscopy of the Hermean surface with
unprecedented spatial and energy resolution. This allows discrimination between different regolith types, and
by combining with data from other instruments, between competing models of crustal evolution and planetary
formation. MIXS will also probe the complex coupling between the planet's surface, exosphere and magnetosphere
by observing Particle Induced X-ray Emission (PIXE).
DEPFET Macropixel detectors, based on the fusion of the combined Detector-Amplifier structure DEPFET with
a silicon drift chamber (SDD) like drift ring structure, combine the excellent properties of the DEPFETs with
the advantages of the drift detectors. As both device concepts rely on the principle of sideways depletion, a
device entrance window with excellent properties is obtained at full depletion of the detector volume.
DEPFET based focal plane arrays have been proposed for the Focal Plane Detectors for the MIXS (Mercury
Imaging X-ray Spectrometer) instrument on BepiColombo, ESAs fifth cornerstone mission, with destination
Mercury. MIXS uses a lightweight Wolter Type 1 mirror system to focus fluorescent radiation from the Mercury
surface on the FPA detector, which yields the spatially resolved relative element abundance in Mercurys crust.
In combination with the reference information from the Solar Intensity X-ray Spectrometer (SIXS), the element
abundance can be measured quantitatively as well. The FPA needs to have an energy resolution better than
200 eV FWHM @ 1 keV and is required to cover an energy range from 0.5 keV to 10 keV, for a pixel size of
300 x 300 μm2. Main challenges for the instrument are the increase in leakage current due to a high level of
radiation damage, and the limited cooling resources due to the difficult thermal environment in the mercury
orbit. By applying an advanced cooling concept, using all available cooling power for the detector itself, and
very high speed readout, the energy resolution requirement can be kept during the entire mission lifetime up to
an end-of-life dose of ~ 3 × 1010 10 MeV p / cm2. The production of the first batch of flight devices has been
finished at the MPI semiconductor laboratory, and first prototype modules have been built. The results of the
first tests will be presented here.
The CTU (Cryogenics Translation Unit) is a low range (±1 mm) high resolution (<50 nm) translation unit to be used at
cryogenic temperature (20K). The unit is a multipurpose device capable of fine closed loop positioning. This device can
be used as active element in IR Instrumentation for compensating thermo-elastic deformation moving optical elements
CTU motion system is based in thin flexures deformation to assure repeatability and moves in closed loop mode by
means of a fine linear actuator and a calibrated non contact capacitive sensor.
This paper describes main design features, how cryogenic testing of main requirements was carried out (including
methodologies used for calibration and submicron verification), tested performances, and main lesson learned during the
This paper describes the conceptual thermo-mechanical design of the MIXS (Mercury Imaging X-ray Spectrometer)
Focal Plane Assembly (FPA). This design is mainly driven by thermal requirements: The Detector is required to operate
below -45 ºC, while the Detector and proximity electronics dissipate more than 2 W, which the passive cooling system
can not handle at the required temperature.
In order to get rid of this cross-constraint, the Detector was separated from the Proximity electronics board, which in turn
has introduced a new dimension of mechanical requirements, as the 370+ bond wires that interconnect both are
extremely delicate and have a high thermal conductivity.
Among the different kinds of Smart Materials one of the more promising materials are the
Shape Memory Alloys (SMA) because of their ability to perform two different tasks: "sensing
and actuating" [1 ,2]. The thermomechanical properties of SMA with view of their use as smart
materials have been recently reviewed [2,3]. Nowadays, three kinds of applications (active
shape control, active modal modification and active strain energy tuning) based specifically on
shape memory alloys are being developed [4,5].
Besides, in order to fulfil the increasing demand of smart materials with a large range of
working temperature, several systems of SMA with higher transformation temperatures (until
240°C) are being explored, such as Ni-Al, Cu-Ni-Al, Fe-Mn-Si-X, Ti-Ni-Pd (see  for a
review). Among them, Cu-Al-Ni shape memory alloys are firm candidates for applications
between 100°C and 240°C because of their low cost, relatively easy processing and good shape
memory properties. Nevertheless, due to their high elastic anisotropy (A13) and large grain
size, the Cu-Al-Ni alloys are brittle, and in general show poor mechanical properties that should
be improved in order to fulfil the requirements for practical applications.
This improvement is usually accomplished through the addition of grain refiners such as
Zr, Ti, B  to obtain a grain size lesser than 1OOm in diameter.