Reliable, efficient electrically pumped silicon-based lasers would enable full integration of photonic and electronic circuits, but have previously only been realized by wafer bonding. Here, we demonstrate the first continuous-wave InAs/GaAs quantum-dot lasers directly grown on silicon substrates with a low threshold current density of 62.5 A/cm 2 , a room-temperature output power exceeding 105 mW, lasing operation up to 120 o C, and over 3,100 hours of continuous-wave operating data collected, giving an extrapolated mean time to failure of over 100,158 hours. The realization of highperformance quantum-dot lasers on silicon is due to the achievement of a low density of threading dislocations on the order of 10 5 cm -2 in the III-V epilayers by combining a nucleation layer and dislocation filter layers with in-situ thermal annealing. These results are a major advance towards silicon-based photonics and photonic-electronic integration, and could provide a route towards reliable and cost-effective monolithic integration of III-V devices on silicon.Increased data throughput between silicon processors in modern information processing demands unprecedented bandwidth and low power consumption beyond the capability of conventional copper interconnects. To meet these requirements, silicon photonics has been under intensive study in recent years 1,2 . Despite rapid progress being made in silicon-based light modulation and detection technology and low-cost silicon optoelectronic integrated devices enabled by the mature CMOS technology 3,4 , an efficient reliable electrically pumped laser on a silicon substrate has remained an unrealized scientific challenge 5 . Group IV semiconductors widely used in integrated circuits, e.g. silicon and germanium, are inefficient light-emitting materials due to their indirect bandgap, introducing a major barrier to the development of silicon photonics. Integration of IIIÐV materials on a silicon platform has been one of the most promising techniques for generating coherent light on silicon. IIIÐV semiconductors with superior optical properties, acting as optical gain media, can be either bonded or epitaxially grown on silicon substrates [6][7][8][9][10][11] , with the latter approach being more attractive for large scale, low-cost, and streamlined fabrication. However, until now, material lattice mismatch and incompatible thermal expansion coefficients between IIIÐV materials and silicon substrates have fundamentally limited the monolithic growth of IIIÐV lasers on silicon substrates by introducing high-density threading dislocations (TDs) 12 .Lasers with active regions formed from III-V quantum dots (QDs), nano-size crystals, can not only offer low threshold current density (J th ) but also reduced temperature sensitivity [13][14][15][16][17] . As shown in Figure 1a, within less than 10 years, the performance of QD lasers has surpassed state-of-the-art quantum-well (QW) lasers developed over the last few decades in terms of J th . QD lasers have now been demonstrated with nearly constan...

Elsaesser, T. (2010). Physical limits of semiconductor laser operation: A time-resolved analysis of catastrophic optical damage. Applied Physics Letters, 97(2), 021110. https://doi

The addition of elevated temperature steps (annealing) during the growth of InAs/GaAs quantum dot (QD) structures on Si substrates results in significant improvements in their structural and optical properties and laser device performance. This is shown to result from an increased efficacy of the dislocation filter layers (DFLs); reducing the density of dislocations that arise at the Si/III-V interface which reach the active region. The addition of two annealing steps gives a greater than three reduction in the room temperature threshold current of a 1.3 μm emitting QD laser on Si. The active region of structures grown on Si have a room temperature residual tensile strain of 0.17%, consistent with cool down from the growth temperature and the different Si and GaAs thermal expansion coefficients. This strain limits the amount of III-V material that can be grown before relaxation occurs.

We have observed the changing light intensity during catastrophic optical mirror damage (COMD) on the timescale of tens of nanoseconds using red-emitting AlGaInP quantum well based laser diodes. Using as-cleaved facets and this material system, which is susceptible to COMD, we recorded the drop in light intensity and the area of damage to the facet, as a function of current, for single, high current pulses. We found that in the current range up to 40 A, the total COMD process up to the drop of light intensity to nonlasing levels takes place on a timescale of hundreds of nanoseconds, approaching a limiting value of 200 ns, and that the measured area of facet damage showed a clear increase with drive current. Using a straightforward thermal model, we propose an explanation for the limiting time at high currents and the relationship between the time to COMD and the area of damaged facet material.

We investigated a series of self-assembled InP quantum dot structures. The Ga concentrations of the Ga x In (1−x) P upper confining quantum well layers were varied from x = 0.43 to x = 0.58, centering on a strain compensated structure. All were grown on a (Al 0.3 Ga 0.7 ) 0.52 In 0.48 P lower confinement layer. Across this range of composition the dot emission wavelength changed approximately linearly with the Ga fraction. Of the compositions used, x = 0.54 gave the best defined and largest magnitude dot absorption spectrum, corresponding to the largest dot density. This resulted in the lowest overall threshold current density with a reduced threshold current temperature sensitivity at room temperature and above. These results are confirmed over two growth series.