Mid-Infrared Black Phosphorus Surface-Emitting Laser with an Open Microcavity

The compact and low-cost surface-emitting lasers in the 3–5 μm mid-infrared (MIR) range are highly desirable for important applications such as gas detection, noninvasive medical diagnosis, and infrared scene projection. Due to the intrinsic noise of general narrow-bandgap semiconductors, the MIR is a challenging region for photonics. Here, we demonstrate the first black phosphorus (BP)-based MIR surface-emitting laser operating at room temperature fabricated with BP as the active gain materials embedded into a SiO 2 /Si 3 N 4 open microcavity on silicon. Optically pumped lasing at ∼3765 nm is successfully realized in the demonstrated device by significantly increased luminescence efficiency in the BP lamellar structure and resolving the general issues for processing BP and other two-dimensional materials as gain medium with the specific design of an open cavity. This is the first demonstration of a BP-based light-emitting device and thus paves a pathway toward monolithic integration of Si-photonics in the MIR range.