Gallium-Nitride Diode Lasers
We develop diode lasers based on the (InAlGa)N material system. We specifically tune their properties to the respective field of application - such as atomic spectroscopy or atomic clocks for integrated quantum technology. For such applications, the lasers must in particular offer narrow-band, temperature-insensitive emission at a precisely defined wavelength. They must also be capable of long-term stable operation with moderate emission powers and good beam quality.
We currently focus our developments on diode lasers with emission wavelengths in the range of 400 to 420 nm:
- RW diode lasers (RW = ridge waveguide) with ridge widths of 2-3 µm: laser operation from approx. 50 mA, max. emission power approx. 100 mW, CW lifetime of more than 500 h
- DFB diode lasers (DFB = distributed feedback) and DBR diode lasers (DBR = distributed Bragg reflector) with monolithically integrated high-order surface Bragg gratings: longitudinal single-mode in continuous wave operation
- External cavity diode lasers (ECDL): their extremely narrow linewidths are of particular interest for FBH's Integrated Quantum Technology
Complete process chain for manufacturing GaN diode lasers in-house:
- simulation of (InAlGa)N heterostructures
- MOVPE growth on GaN substrates incl. material analysis
- chip process technology
- facet technology
- chip assembly on submounts and heat sinks
- characterization, e.g. power-current-voltage curves, spectra as well as far and near fields
- long-term stress tests
In the LARUS* project, we are developing laser sources in the blue-violet spectral range for optical frequency standards based on rubidium for space applications. For the realization of this project, laser diodes with a small linewidth and long lifetime are needed. The small linewidths will be achieved with ridge waveguide laser diodes in an external-cavity diode laser setup. To increase the lifetime, among other things, the epitaxial structure will be optimized and the influence of the ambient atmosphere on the stability of the laser facets will be investigated.
*Development of a laser source for an atomic clock based on rubidium
In the UVSimTec* project, we are developing together with our project partners novel, AlGaN-based laser diodes to generate an emission in the UVC spectral range. The FBH develops AlN/sapphire templates, which serve as basis for the deposition of the laser heterostructure. By using or by a combination of sputtered AlN, high temperature annealing and lateral patterning, templates with an up to two orders of magnitude smaller defect density compared to standard MOVPE grown sapphire/AlN templates are to be realized.
*UV Lasers: From Modeling and Simulation to Technology