High-power heterogeneously integrated mode-locked laser enabled by a booster amplifier

Integrated mode-locked lasers have emerged as promising comb sources over recent years, with the prospect of their use in many applications such as telecommunications, lidar and dual-comb spectroscopy. While these integrated implementations have the advantage of a smaller footprint and cost compared to their table-top counterparts, the lower output powers have been a significant downside for their use in applications. Here, we demonstrate a heterogeneously integrated III/V-on-silicon nitride mode-locked laser with a 3 GHz repetition frequency. The heterogeneous integration is enabled by micro-transfer printing, which is a versatile approach utilized not only for the integration of the III/V semiconductor optical amplifier, but also a silicon interposer coupon. This two-step micro-transfer printing approach is used to integrate a mode-locked laser combined with a booster amplifier, placed at one of the mode-locked laser outputs, where the output power is amplified by up to 10.5 dB, enabling average powers of 11 dBm on-chip.