Low-threshold thin-film III-V lasers bonded to silicon with front and back side defined features

A III–V thin-film single-quantum-well edge-emitting laser is patterned on both sides of the epitaxial layer and bonded to silicon. Injected threshold current densities of $420\mathrm{A}∕{\mathrm{cm}}^2$ for gain-guided lasers with bottom p-stripes and top n-stripes and $244\mathrm{A}∕{\mathrm{cm}}^2$ for index-guided bottom p-ridge and top n-stripe lasers are measured with a lasing wavelength of $\sim 995\mathrm{nm}$. These threshold current densities, among the lowest for thin-film edge-emitting lasers on silicon reported to date (to our knowledge), enable the implementation of integrated applications such as power-efficient portable chip-scale photonic sensing systems.