Low-threshold AlGaN-based deep ultraviolet laser enabled by a nanoporous cladding layer

We demonstrated an AlGaN-based multiple -quantum -well (MQW) deep ultraviolet (DUV) laser at 278 nm using a nanoporous (NP) n-AlGaN as the bottom cladding layer grown on the sapphire substrate. The laser has a verylow -threshold optically pumped power density of 79 kW/cm2 at room temperature and a transverse electric (TE)polarization-dominant emission. The high optical confinement factor of 9.12% benefiting from the low refractive index of the nanoporous n-AlGaN is the key to enable a low -threshold lasing. The I-V electrical measurement demonstrates that an ohmic contact can be still achieved in the NP n-AlGaN with a larger but acceptable resistance, which indicates it is compatible with electrically driven laser devices. Our work provides insights into the design and fabrication of low -threshold lasers emitting in the DUV regime. (c) 2024 Optica Publishing Group