Electrically packaged silicon-organic hybrid (SOH) I/Q-modulator for 64 GBd operation

Silicon-organic hybrid (SOH) electro-optic (EO) modulators combine small footprint with low operating voltage and hence low power dissipation, thus lending themselves to on-chip integration of large-scale device arrays. Here we demonstrate an electrical packaging concept that enables high-density radio-frequency (RF) interfaces between on-chip SOH devices and external circuits. The concept combines high-resolution $\mathrm{Al_2O_3}$ printed-circuit boards with technically simple metal wire bonds and is amenable to packaging of device arrays with small on-chip bond pad pitches. In a set of experiments, we characterize the performance of the underlying RF building blocks and we demonstrate the viability of the overall concept by generation of high-speed optical communication signals. Achieving line rates (symbols rates) of 128 Gbit/s (64 GBd) using quadrature-phase-shiftkeying (QPSK) modulation and of 160 Gbit/s (40 GBd) using 16-state quadrature-amplitudemodulation (16QAM), we believe that our demonstration represents an important step in bringing SOH modulators from proof-of-concept experiments to deployment in commercial environments

Transmitter Beam Bias Verification for Optical Satellite Data Downlinks with Open-Loop Pointing – the 3-OGS-Experiment

Optical free-space data downlinks from LEO satellites benefit considerably from reduced effort on the space segment, when a dedicated pointing mechanism and active tracking of a ground beacon can be avoided. Instead, the attitude of the satellite is dynamically determined from its star cameras and other sensors. Initial calibration for this technique requires recording of the spatial and temporal beam distribution on the Earth’s surface. We describe the measurement of the beam intensity on ground by the power detectors of three ground stations in parallel, exemplarily for one specific downlink. From this data we derive the instantaneous center of gravity of the beam spot, and its dynamic movement during the downlink. By comparison with the satellite’s own recorded attitude data and its error, the dynamic offset to be corrected on the satellite can be calculated, resulting in optimized pointing-control for future operational open-loop downlinks

Design of an Optical System for three Wavelength Quantum Key Distribution

With the rise of quantum computers, today’s encryption methods are not safe from being broken in the future. With the help of Quantum Key Distribution, however, we can move towards encryption technologies, that can not be broken due to the underlying mathematical principles. This thesis describes the development of an optical system to demonstrate Quantum Key Distribution from an airplane to ground in the QuNET flight campaign. The optical system is developed for an existing mechanical setup, that can be mounted into one of DLRs research airplanes. The development starts from theoretical calculations, running through several iterations of optimisation, up to the point, that a working setup has been developed, that is usable under realistic flight scenarios for the planned experiments. With a first tolerancing analysis, a first step is done towards the manufacturing of the developed system