Photonic-integrated circuits (PICs) are a key enabler for the ultimate miniaturization of next-generation optical computers that can fit in the palm of your hand. However, the realization of fully functional PICs is currently limited by the absence of an efficient light source on silicon (Si), thus making a practical Si-compatible light source the Holy Grail. Especially, it has been thus far considered close to impossible to create a practical on-chip laser using Si-compatible group IV semiconductor materials (e.g. germanium (Ge)) owing to their indirect bandgap nature. Strain-engineered Ge material has recently garnered much attention for the dramatic reduction of the lasing threshold of group IV lasers because large tensile strain fundamentally alters the Ge’s bandstructure.

Here, we present our recent research works on highly strained group IV materials on a Si chip for the realization of low-threshold on-chip lasers. In the first part, we will introduce our innovative strain engineering platforms that can create direct bandgap Ge nanowires by inducing >5% elastic tensile strain. In the second part, we will present the first experimental observation of low-threshold optically pumped lasing in highly strained Ge nanowires. The strain engineering of direct bandgap germanium-tin will also be described for the ultimate reduction of the lasing threshold.