Plasmonic nanolasers have ultrahigh lasing thresholds, especially thosedevices for which all three dimensions are truly subwavelength. Because of amomentum mismatch between the propagating light and localized optical field ofthe subwavelength nanocavity, poor optical pumping efficiency is anotherimportant reason for the ultrahigh threshold but is normally always ignored.Based on a cavity-embedded nanoantenna array design, we demonstrate aroom-temperature low-threshold plasmonic nanolaser that is robust,reproducible, and easy-to-fabricate using chemical-template lithography. Themode volume of the device is~0.22({\lambda}/2n)3 (here,{\lambda} is resonantwavelength and n is the refractive index), and the experimental lasingthreshold produced is ~2.70MW/mm2. The lasing polarization and the function ofnanoantenna array are investigated in detail. Our work provides a new strategyto achieve room-temperature low-threshold plasmonic nanolasers of interest inapplications to biological sensoring and information technology.
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