Ultraviolet C random lasing at 230-280 nm from Pr³⁺ doped bulk crystal resonators by two-photon absorption

Ultraviolet solid-state light sources, especially in the short-wave ultraviolet band, are attracting great attention for potential applications in high-density optical data storage, biomedical research, and water and air purification and sterilization. As one of the means to generate solid-state short-wavelength lasers, upconversion technology, which can transform a low-energy photon to a high-energy photon, has a simple structure and does not require strict phase-matching conditions. However, because of the high non-radiative decay rate during multiphoton absorption process, the short-wave upconversion ultraviolet lasing is still difficult to achieve. Here, under 450 nm blue laser excitation, we have successfully obtained ultraviolet C random lasing from a Pr³⁺ doped YPO₄ single crystal via two-photon absorption. Presently, ultraviolet C random lasing with the wavelength range of 230-280 nm is the shortest wavelength for upconversion lasing emission.