The dynamics of the catastrophic optical damage process under continuous wave operation is analyzed in red-emitting high-power diode lasers by means of combined thermal and optical near-field (NF) imaging with cameras. The catastrophic process is revealed as extremely fast (Δt⩽2.3ms) and spatially confined. It is connected with a pronounced impulsive temperature change. Its coincidence with the most intense NF filament is indicative of the critical nature of thermal runaway in the catastrophic process.

The authors present a detailed investigation of defects generated during catastrophic optical damage (COD) in high-power 650nm AlGaInP lasers using microphotoluminescence (μ-PL) mapping, focused ion beam (FIB) microscopy, and deep-etching techniques. High-resolution μ-PL images demonstrated that during COD, nonradiative dark line defects (DLDs) originate from the front mirror of the laser and propagate in several branches into the laser perpendicular to the output facet. Furthermore, FIB microscopy identified the epitaxial layers affected by COD, revealing that DLDs are confined to the active region. In addition, deep etching confirmed that these defects have a noncrystalline nature.

Facet temperature changes in broad-area red-emitting high-power AlGaInP lasers are analyzed by means of micro-Raman spectroscopy. Measurements as a function of injection current demonstrate that the temperature at the laser output facet rises linearly with optical output power. Temperature profile measurements across the laser stripe show a strong correlation between near field intensity, facet temperature, and catastrophic optical damage (COD). Additionally, temperature-power analyses reveal that a critical facet temperature is needed to induce COD. The consistent results produced by complementary measurement techniques indicate that absorption of stimulated photons at the laser facet is the major source of facet heating.

The emission wavelength of broad-area AlGaInP/InGaP quantum-well lasers is tuned by the application of high hydrostatic pressure and low temperature from 645 down to 575 nm, i.e., from the red through the orange to yellow spectral range. Emission powers up to 300 mW are obtained in the full tuning range. The pressure and temperature dependence of threshold currents indicates that leakage occurs into the L and X minima in the barriers.

In this paper, a comprehensive model to describe the small-signal modulation response of ultra-high performance single-and multi-mode vertical-cavity surface-emitting lasers (VCSELs), with modulation bandwidths exceeding 30 GHz, is presented. Traditionally, utmost simplified dynamic models are used to extract dynamic figures of merit from singlemode edge-emitting lasers. These methods are later on also applied to evaluate the dynamic performance of VCSELs, even though these devices have a very different geometrical layout and modal confinement. However, to understand the dynamic performance of high-speed VCSELs, a model supporting the transverse and longitudinal mode profile, and the driving current inhomogeneity in the active region, is needed. Therefore, multi-mode VCSEL rate equations are established here. Moreover, to access the dynamic figures of merit of these devices, a comprehensive analytical fitting function based on our carrier reservoir splitting approach is derived. Thus, because of the high carrier and photon densities inside these optimized VCSELs, the common carrier reservoir splits up as a result of numerous effects such as mode competition, carrier diffusion and spatial hole burning. These and other effects have a tremendous impact on the small signal modulation response shape and bandwidth, and also on the current distribution profile in the carrier reservoirs. Compared with our recently reported work, this novel model presented includes the effects of gain compression and inhomogeneous current injection between the different lasing modes. Consequently, it is found that the further tuning of our multi-mode VCSEL dynamic model, to include these effects, yields a more physical and consistent figures of merit of high-performance VCSELs.