Longitudinal mode competition in (Al,In)GaN laser diodes at λ = 445nm and 515 nm with mode competition frequencies from 10 MHz to 150 MHz is observed. Up to two dozen lasing modes oscillate with the lasing mode rolling from the short wavelength edge to the long wavelength edge of the gain profile. The experimental results can be described very well with a set of multi-mode rate equations including self-, symmetric and asymmetric cross gain saturation. By tuning essential parameters of the gain saturation terms, mode competition disappears and single mode operation as well as mode clustering is found. This proves that the mechanisms of gain saturation have not only a profound impact on the complex temporal-spectral behavior but also explains mode clustering in (Al,In)GaN laser diodes, both in pulsed and continuous wave (cw) operation as a natural nonlinear effect without the necessity to add noise.

We present a blue InGaN research and development superluminescent light-emitting diode (SLED) that is suitable for picoprojection. The SLED reaches an output power of >100 mW with a peak wavelength of 443 nm and a spectral bandwidth of >2.6 nm as well as a single-mode far-field driven in cw mode at 25 °C. In order to figure out an optimized waveguide design, which enables such a high output power at lowest operation current, we compare the performance of diodes with curved and tilted shaped ridges in detail, using the lasing threshold current as a criterion for lasing or superluminescence, respectively.

Passive mode-locked pulses with repetition frequencies in the range 40 to 90 GHz were observed in blue-violet GaN-based quantum-well lasers without external cavities. The lasers had two-section geometry with built-in saturable absorber section. The individual pulses had durations as short as 3-5 ps at peak powers of around 320 mW

We present an investigation of the degradation of InGaN/GaN laser diodes grown on a GaN substrate. The results indicate that: (i) Ageing induces a significant increase in the threshold current (Ith) of the lasers, which is attributed to an increase in non-radiative recombination; (ii) Ith increase is correlated to a decrease in the micro-cathodoluminescence signal measured (after the removal of the top metallization) in the region under the ridge; (iii) micro-photoluminescence measurements indicate that constant current stress increases non-radiative recombination within the quantum wells (and not only within the barriers), and induces an increase in the emission wavelength of the degraded regio

Self-Q-switching in GaN-based multisection laser diodes (MS-LDs) is investigated. The influence of the absorption on threshold currents and charge carrier lifetimes in the absorber section are measured and discussed in the context of the band structure at high reverse bias. Our system employs a bowtie geometry, i.e., with the absorber section positioned in the center of the laser cavity and a tapered shape of the laser ridge. The shortest pulses were in the 10 picosecond range, obtained at a constant reverse bias of -36 V applied to the absorber section, the gain section was driven at 0.57 A. The emission wavelength was around 405 nm.