External feedback can disturb the emission properties of high-power diode lasers. The FBH has developed a measurement setup to study and quantify these effects. As a result, a new generation of high-power diode lasers with reduced sensitivity to external feedback could be developed.
Research News 2019
The FBH has fabricated broad area lasers using a 2-step epitaxial growth process with an intermediate implantation of ions outside of the active laser stripe. The second growth step removes the crystal damage and activates the implanted dopants so that highly resistive regions are formed.
They deliver field plots providing descriptive insight into the measurement process. A further advantage is the ability to run systematic perturbation studies to estimate the influence of geometry and material parameters on the quality of the calibration.
The FBH has developed a laser system with high beam quality that is capable of combining two laser beams practically without any losses. The coupled radiation reaches >12 W in cw mode at 980 nm wavelength and an output beam quality factor of M2 < 1.5.
FBH contributes its expertise in the field of process technology and has developed a design which combines sufficient mechanical stability with excellent optical properties.
FBH and IKZ worked on the fabrication of lateral β-Ga2O3-based power transistors with enhanced device performance through combining optimized layer growth and improved process technology.
FBH has investigated current induced degradation processes of deep UV LEDs. The derived acceleration factors point to the importance of optimizing the charge carrier distribution to improve the device lifetime
FBH demonstrated that ECDL gain chips with angled-facet waveguides offer a higher spectral purity over a wider current range as compared to standard AR-coated straight waveguides. These chips are therefore better suited for applications requiring a large tuning range.
The FBH comprehensively investigates discrete level supply modulation, which shows promising performance for the upcoming large instantaneous modulation bandwidth. Developments target high efficiency GaN in future 5G telecom and space applications.
FBH has transferred its established surface grating technology from DBR to DFB lasers. The new technological platform was succesfully demonstrated at 670 nm and can now be used for a multitude of other wavelengths.
The FBH has developed a fully digital GaN-based transmitter module aiming to replace the analog transmitter chain. It extends the boundary of the digital domain behind the power amplifier, yielding several benefits including compactness, low energy consumption and flexibility.
FBH has been continuously improving the performance of red emitting diode lasers used for high-power applications. Optimized FBH bars were mounted into stacks by our industrial partners, with 8-bar stacks now operating reliably with output power of more than 2 kW at a wavelength of 665 nm.
The FBH has developed a new miniature plasma source that demonstrated for the first time that an inductively coupled microwave plasma can be excited at atmospheric pressure. This source delivers a cold plasma with high efficiency.
FBH explores two technological approaches to realize buried current apertures leading to increased efficiency and beam quality of laser diodes. Both the buried mesa approach and implanted apertures are based on 2-step epitaxy.
Power and broadband amplifiers as well as oscillators are realized at FBH with the in-house developed transfer-substrate InP DHBT process. Effective circuit design requires accurate models and therefore the noise of these InP DHBTs is comprehensively characterized and modeled.
The FBH has developed a very compact diode laser module emitting in the yellow-green spectral range with power levels in the watt range. The system uses a novel butterfly housing and targets biomedical and spectroscopic applications.
Controlling wafer bow is important in order to minimize performance variations between devices on a wafer. FBH recently developed and qualified a laser patterning process on 305 nm UVB LEDs that significantly reduces wafer bow.
The LISA satellite mission aims to detect and characterize gravitational waves. To achieve this, three laser interferometers will be used that require suitable metrology lasers. The FBH has developed a 1064 nm diode laser with resonant optical feedback to be used as seed laser, aiming to replace Nd:YAG NPRO lasers used so far.
LiDAR sensors have become a fast growing market segment with a broad range of applications, from automotive to robotics. The FBH has developed the required GaN-based laser drivers, delivering 100 W optical pulse peak power with pulse widths from 3-10 ns and pulse currents from 180-250 A.