Discrete level supply modulation (class-G) shows potential for integrated mm-wave power amplifiers targeting 5G and space applications. The integrated switches can accommodate high instantaneous bandwidth.
Research News 2021
Efficient diode lasers at 780 nm are needed to pump thulium-doped solid-state lasers used in high-energy class applications. FBH scientists have recently improved the epitaxial layer structures to increase peak output power and efficiency of diode pumps.
Non-linear optical processes take place in waveguides with tiny cross sections and high index contrast. In order to achieve high efficiency, it is necessary to minimize optical losses. FBH has succeeded in this due to new findings by characterizing device surfaces with a new atomic force microscope.
Integrating a DFB diode laser and a rubidium vapor cell led to one of the most compact and stable optical frequency references of this type. The 70 × 26 × 19 mm³ system provides light with a relative frequency instability of 1.7 x 10-12 at 1 s averaging time.
The FBH has developed a miniaturized MOPA laser source at 626 nm wavelength, emitting up to 250 mW in a single longitudinal mode. It is integrated into a sealed package and allows frequency doubling to 313 nm, suited for laser cooling of beryllium ions.
The FBH has investigated the thermal stability of tellurium (Te) as donor in GaAs during further growth at high temperatures. These studies have enabled laser diodes with stacked active regions connected by Te- and carbon-doped tunnel junctions.
The FBH has developed ultra-wideband MMIC amplifiers with a record gain-bandwidth product of beyond 1.75 THz. They are based on the institute’s InP DHBT technology and provide a very high output referred third-order intercept point >20 dBm and an excellent average gain of 24 dB.
The FBH has developed and fabricated tapered laser diodes with excellent features, suited e.g. for novel Raman imaging techniques. The devices are based on an established vertical structure and offer narrow spectral emission.
The new medium-current implanter system in FBH’s cleanroom allows an implantation energy up to 500.000 V, a beam current of up to 2 mA and using various ion sources. It also comprises a single wafer substrate holder that can be heated up to 800 °C during implantation.
The FBH has developed a novel monolithically integrated GaAs-based extended cavity diode laser (mECDL) emitting at 1064 nm with an astounding 3 dB linewidth of 25 kHz @ 1 ms - the smallest linewidth achieved with a monolithic laser design.
FBH scientists show 3.3 ns long pulse operation with more than 18 W output power and an excellent brightness from novel tapered-ridge-waveguide lasers. Such lasers generating few-nanosecond-long optical pulses are key components of scanning LiDAR systems.
Together with European partners, the FBH is developing reliable techniques for on-wafer measurements to cover frequencies from 110 GHz to 1,100 GHz. This is an important contribution towards the development of electronics for future generations of wireless systems.
Photoluminescence (PL) is sensitive on various characteristics of III-V semiconductors which are related to conductivity and light generation efficiency. The materials analytics group at FBH uses various PL methods to optimize crystal growth for GaN laser diodes.
FBH and its partner TU Berlin have succeeded in significantly increasing the lifetime of its UVC LEDs to beyond 10,000 h by using AlN base layers of high crystalline quality. Crucial for this improvement is a reduction of the threading dislocation densities in the active region.
FBH has developed a potential shifting driver amplifier. The compact module contains a novel inhouse GaN driver chip. It delivers a voltage gain of about 11 at a usual GaN-HEMT input load and provides a potential shift between -1.5 V and -11 V, respectively.
FBH has succeeded in fabricating nanostructures in diamond with a diameter of about 200 nm into which single quantum emitters were incorporated. These nanopillars enable the efficient collection of single photons. This is crucial for a variety of applications in quantum technology.
Novel kW-class 780 nm pump modules with near symmetric beam quality have been demonstrated, suited for high repetition rate, long-pulse applications, without micro-channel coolers – a key enabling technology for emerging high-energy-class Mid-IR lasers.
Low-inductance switching and low-thermal impedance environments are key parameters to enable GaN devices high switching speed. FBH has developed AlN power electronic modules that can serve as fundamental building blocks of large-scale plug-and-play power electronic systems.
The FBH has developed an ultra-compact high-power micromodule. It comprises six inhouse-developed tapered laser diodes emitting in the NIR spectral range, delivering an output power > 30 watt with high beam quality.