The propagation of anisotropic polaritons along previously forbidden directions through a topological transition is demonstrated.

Focusing of in-plane hyperbolic PhPs into deep subwavelength focal spots provides enhanced field confinement and absorption.

Hole gases in planar germanium can have high mobilities in combination with strong spin-orbit interaction and electrically tunable $g$ factors, and are therefore emerging as a promising platform for creating hybrid superconductor-semiconductor devices. A key challenge towards hybrid Ge-based quantum technologies is the design of high-quality interfaces and superconducting contacts that are robust against magnetic fields. In this work, by combining the assets of aluminum, which provides good contact to the Ge, and niobium, which has a significant superconducting gap, we demonstrate highly transparent low-disordered JoFETs with relatively large $I_{\text{C}}{R}_{\text{N}}$ products that are capable of withstanding high magnetic fields. We furthermore demonstrate the ability of phase-biasing individual JoFETs, opening up an avenue to explore topological superconductivity in planar Ge. The persistence of superconductivity in the reported hybrid devices beyond 1.8 T paves the way towards integrating spin qubits and proximity-induced superconductivity on the same chip.

A single-junction germanium solar cell with a photonic crystal nanostructured surface has been developed. The solar cell comprises a Ge $p\text{-}n$ junction and an InGaP window layer. The InGaP window layer has been nanopatterned with an extended photonic crystal structure consisting on a triangular lattice of holes with submicronic sizes. Enhancements of the external quantum efficiency of 22% for a wide range of wavelengths and up to a 46% for specific wavelengths have been measured, which implies an increase in photocurrent between 11% and 22%. A clear correlation with the area of photonic crystal patterned has been observed.