A high-performance 1.3 μm InAs/GaAs quantum-dot laser directly grown on Si substrates has been achieved by using InAlAs/GaAs strained-layer superlattice serving as dislocation filter layers (DFLs). The Si-based laser achieves lasing operation up to 111°C with a threshold current density of 200 A/cm 2 and an output power exceeding 100 mW at room temperature.Introduction: Owing to the limitations in device speed and performance in Si-based electronics, Si photonics has attracted strong interest in recent years, with steady process being made to achieve ultra-fast optical data processing [1]. Although Si-based light generations and modulation technologies have been demonstrated widely [2-4], progress towards an efficient Si-based laser has been limited because of the indirect bandgap of silicon. In contrast, III-V compound semiconductors have a direct band structure and have had an impressive 'show' in many photonic applications [5,6]. Monolithic growth of highperformance III-V lasers on Si substrates would therefore provide an ideal test bed for the fabrication of electrically pumped lasers on Si substrates.However, one of the major roadblocks remaining to be solved has been the formation of high-density threading dislocations (TDs), resulting from the lattice mismatch and thermal expansion coefficient between III-V compounds and Si [4]. It has been clearly demonstrated that any TDs propagating into the active media become a non-radiative recombination centre, and hence debilitate laser performance. Therefore, for direct growth of III-V on Si substrates, dislocation filter layers (DFLs) between Si and III-V active element play a crucial role in reducing the density of TDs [7]. Recently, III-V quantum dots (QDs) have emerged as a promising technique for practical III-V/Si photonics, since it offers several important advantages over traditional III-V/Si quantum well technologies, including the improved tolerance to defects and delta-function-like density of states. As a result, impressive results on QD lasers have been demonstrated on Ge, Ge-on-Si and Si substrates [8][9][10][11][12][13].In this Letter, we demonstrate a high-performance InAs/GaAs QD laser directly grown on Si substrates using InAlAs DFLs. The device exhibits lasing at 1.26 μm with a threshold current density of 200 A/ cm 2 along with single facet output power exceeding 100 mW at room temperature. Significantly, lasing operation for heat sink temperature up to 111°C has been achieved.

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