Improved light transmission for III-V lasers monolithically integrated on Si platforms

We propose a strategy to monolithically integrate active III-V lasers and passive dielectric devices, where the passive waveguides are fabricated after the MBE growth of the III-V semiconductors on a planar Si substrate. This avoids any airgap at the active/passive interface, replaced by a thin dielectric interface layer which improves the light coupling efficiency. We demonstrate GaSb DLs butt-coupled to SiN waveguides with ∼23% transmission after 2 mm SiN, corresponding to ∼35% transmission at the active/passive interface. We propose several routes to further increase the transmission factor. This strategy eliminates the need for trenches or pockets, which have been shown to cause poor quality material near the dielectric stack facet and to affect the laser lifetime. This strategy thus paves the way for an optimized route to monolithically integrate active and passive photonic devices with a high light coupling efficiency.