  Metallic-Cavity lasers or plasmonic nanolasers of sub-wavelength sizes have
attracted great attentions in recent years, with the ultimate goal of achieving
continuous wave (CW), room temperature (RT) operation under electrical
injection. Despite great efforts, a conclusive and convincing demonstration of
this goal has proven challenging. By overcoming several fabrication challenges
imposed by the stringent requirement of such small scale devices, we were
finally able to achieve this ultimate goal. Our metallic nanolaser with a
cavity volume of 0.67{\lambda}3 ({\lambda}=1591 nm) shows a linewidth of 0.5 nm
at RT, which corresponds to a Q-value of 3182 compared to 235 of the cavity Q,
the highest Q under lasing condition for RT CW operation of any sub-wavelength
laser. Such record performance provides convincing evidences of the feasibility
of RT CW metallic nanolasers, thus opening a wide range of practical
possibilities of novel nanophotonic devices based on metal-semiconductor
structures.
