  Random lasers use radiative gain and multiple scatterers in disordered media
to generate light amplification. In this study, we demonstrate a random laser
based on diamond nanoneedles that act as scatterers in combination with
fluorescent dye molecules that serve as a gain medium. Random lasers realized
using diamond possess high spectral radiance with angle-free emission and
thresholds of 0.16 mJ. The emission dependence on the pillar diameter and
density is investigated, and optimum lasing conditions are measured for pillars
with spacing and density of 336 nm and ~ 2.9x10^10 cm-2. Our results expand the
application space of diamond as a material platform for practical, compact
photonic devices and sensing applications.
