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The laser characteristics of 0.98 µm vertical-cavity surface-emitting lasers based on sub-monolayer InGaAs quantum dots (QDs) were studied in a broad temperature range. Devices demonstrated low internal optical losses, high differential efficiency and relatively small resistances due to the QD active region together with an optimal design of doped distributed Bragg reflectors. It is found that the temperature dependence of threshold current and differential efficiency depends not only on the temperature sensitivity of the active region, but also on the lineshape of the gain curve and spectral misalignment between the gain maximum and cavity mode. A simple method of estimation of gain-cavity detuning has been proposed. [ABSTRACT FROM AUTHOR]

1.5 m-range laser diodes based on InAs/InGaAs quantum dots (QDs) grown on metamorphic (In, Ga, Al)As layers, which were previously deposited on GaAs substrates using a defect reduction technique (DRT), are studied. More than 7 W total output power operation in the pulsed mode is shown in broad area lasers. It is shown that the narrow stripe lasers operate in the continuous wave (CW) and the single transverse mode at current densities up to 22 kA cm−2 without significant degradation. CW output power in excess of 220 mW at 10 C heat sink temperature is demonstrated. 800 mW single-mode output power in the pulsed regime is obtained. It is also shown that the lasers demonstrate the absence of beam filamentation up to the highest current densities studied. First studies on the dynamics of the lasers show a modulation bandwidth of ∼3 GHz, limited by device heating. Eye diagrams at 2.5 Gbit s−1 and room temperature (RT) have been performed. Aging tests demonstrate >800 h of CW operation at ∼50 mW at 10 C heat sink temperature and >200 h at 20 C heat sink temperature without decrease in optical output power. The results indicate the high potential of metamorphic growth using the DRT for practical applications, such as 1500 nm GaAs vertical cavity surface emitting lasers (VCSELs). [ABSTRACT FROM AUTHOR]

We report on GaAs-based broad area (100 µm) 1.3 µm quantum dot (QD) lasers with high CW output power (5 W) and wall-plug efficiency (56%). The reliability of the devices has been demonstrated beyond 3000 h of CW operation at 0.9 W and 40 °C heat sink temperature with 2% degradation in performance. P-doped QD lasers with a temperature-insensitive threshold current (T0 > 650 K) and differential efficiency (T1 = infinity) up to 80 °C have been realized. [ABSTRACT FROM AUTHOR]

The influence of waveguide parameters (thicknesses and contrasts in both transverse and lateral directions) on optical mode compositions in narrow-ridge lasers is numerically investigated. The proposed numerical model explains our experimental results on the drastic difference in optical mode compositions in broad-area and narrow-ridge lasers processed from the same wafer based on a broadened GaAs/AlGaAs transverse-waveguide heterostructure. It is shown that in the broadened transverse waveguides the fundamental mode tends to have a much lower 2D optical confinement factor than high-order modes. We suppose that waveguides possessing no more than two transverse eigenmodes would provide more opportunities for designing narrow-ridge lasers with robust single-mode emission. [ABSTRACT FROM AUTHOR]

We report on low threshold current density (<400 A cm−2) injection lasing in (AlxGa1–x)0.5In0.5P–GaAs-based diodes down to the green spectral range (<570 nm). The epitaxial structures are grown on high-index (611)A and (211)A GaAs substrates by metal–organic vapor phase epitaxy and contain tensile-strained GaP-enriched insertions aimed at reflection of the injected nonequilibrium electrons preventing their escape from the active region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15° for (611)A substrates. The lasing at the wavelength of 569 nm is realized at 85 K. In an orange–red laser diode structure low threshold current density (190 A cm−2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrated room temperature lasing at 628 nm at ∼2 kA cm−2 and a total power above 3 W. The red laser diodes grown on (211)A substrates demonstrated a far field characteristic for vertically multimode lasing indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However, as expected from previous research, the temperature stability of the threshold current and the wavelength stability were significantly higher for (211)A-grown structures. [ABSTRACT FROM AUTHOR]

A single sheet of high-density InGaAs quantum dots (QDs) is used as a gain medium of InGaAs–GaAs–AlGaAs lasers. The devices operate at high power in the continuous mode beyond 160 °C with an emission wavelength up to ∼1.27 μm. At short cavity lengths a strong broadening (>300 nm) of the electroluminescence spectrum is observed at high current densities, permitting light sources for broadly wavelength tuneable and multi-wavelength infrared lasers based on a single gain chip, and related frequency conversion devices for the whole visible spectrum range. High power cw operation (>2 W) limited by catastrophic optical mirror damage is realized. [ABSTRACT FROM AUTHOR]

We report on 1.33 µm quantum dot (QD) lasers grown on GaAs substrates that show a modal gain of 45 cm[?]1, low threshold current density of 150 A cm[?]2 and room-temperature continuous wave output power of 2.5 W. The active region is based on ten InAs/InGaAs/GaAs quantum dot layers formed by activated phase separation. High structural quality of the active region is achieved, owing to minimization of the total amount of strained material per QD layer. The optical confinement factor is increased by exploiting high Al composition (80%) in the cladding layers. A modal gain over 20 cm[?]1 in the 1315-1345 nm wavelength range is revealed by the Hakki-Paoli technique at a low current density of 500 A cm[?]2. [ABSTRACT FROM AUTHOR]