Forschungsnews

FBH has significantly increased the optical power of its 760 nm tapered lasers to 9 W while maintaining good beam quality with high power in the central lobe (> 60 %) – due to an optimized epitaxial structure and ridge waveguide length.

With the unique 5G-MIMO hardware measurement system and the developed IF and RF calibration procedure, we have now verified 1-port measurements at 12.5 GHz with a signal with an instantaneous IF bandwidth of 500 MHz.

FBH has developed an optical frequency reference using two-photon spectroscopy of rubidium, reaching a short-term stability of 1.5 x 10^-13. This setup will be further miniaturized towards a turn-key clock system suited for compact satellites.

The high-performance equipment allows to etch, anneal, and deposit in one single cluster tool, thus offering well-defined surface conditions and a low level of cross-contamination. This opens up new possibilities for highly integrated device concepts.

SERDS using customized diode lasers is a powerful tool for soil analysis in the presence of strong fluorescence interference. For the first time, SERDS spectra enabled to predict the soil organic matter content.

Using the in-house InP DHBT technology, FBH developed an ultra-compact 315 GHz push-push signal source with integrated antenna, allowing for array configurations. It delivers -10 dBm radiated output power in free-space with only 21 mW DC power consumption.

A new facet passivation technology based on ultra-high vacuum cleaving has been established at FBH. Initial results demonstrate a significantly enhanced facet stability for ridge-waveguide lasers operating at 1064 nm.

A novel chip package concept with lens and distributed Bragg reflector filter reduces skin-damaging long-wavelength UVC contribution of 233 nm AlGaN-based LEDs. A prototype has already been successfully used for skin-tolerant UV antisepsis.

Significant improvements in FBH’s processing technology recently enabled us to qualify our high-power lasers for space applications. These lasers will be used in scientific experiments to probe the limits of quantum mechanics on board the ISS.

A new generation of plasma sources has been designed to study the inductive coupling behavior in more detail. Special optical and microwave methods are applied to investigate the plasma properties of oxygen, primarly relevant for semiconductor technologies.

Undoped AlN layers on high-temperature annealed AlN lead to uncontrollable formation of irregular dislocation half-loops. Si doping prevents this defect formation, showing a way towards better crystalline quality and further improvement of AlGaN UV LEDs.

FBH has realized wavelength-stabilized broad-area lasers based on an advanced highly asymmetric epitaxy. They achieve the highest ever published combination of efficiency and power in a monolithically grating-stabilized laser.

FBH has realized the first switch-mode class-F like W-band power amplifier in InP-DHBT technology. The design concept is an important step to push efficiency for 6G front-ends and to advance digitization for next-generation communication.

FBH is developing a sensor for magnetic fields based on ensembles of atomic defects in diamond. This highly doped diamond is sensitive to magnetic fields and can be read out optically by using an infrared laser transmission signal.

We implemented for the first time the ridge waveguide section current for phase control in a novel coherent beam combining setup, achieving remarkably high combining efficiencies of > 80 % and an optical power of 3.5 W at low operating currents.

FBH is developing the process technology to realize vertical fin field-effect transistors based on GaN and β-Ga₂O₃. The device concept is a promising approach for next-generation highly efficient power converters.

An advanced InP HBT MMIC process yielded a stable node size of 300 nm with alignment quality of <20 nm. A system integration concept (using a low-temperature flip-chip process) has also been developed.

FBH provides an open-source Python toolbox for automating and optimizing direct writing with focused ion beams. The power of the toolbox has been demonstrated by, among others, the creation of phononic crystal resonators based on graphene.