Characterization of Plasmonic Nanolasers in Spatial, Momentum, and Frequency Spaces

Plasmonic nanolasers are a new class of laser device where surface plasmons are amplified by the stimulated emission in a plasmonic nanocavity. In contrast to conventional lasers, the physical size and the mode volume of plasmonic nanolasers can shrink beyond the optical diffraction limit. The strongly confined optical field leads to high performance of plasmonic nanolasers including ultrafast modulation speed and ultralow power consumption, while on another hand introduces challenges in characterizing their basic lasing properties. In this paper, we systematically characterize the lasing properties of plasmonic nanolasers in spatial, momentum, and frequency spaces simultaneously via leakage radiation microscopy and demonstrate a method to identify the exact lasing modes in a multimode plasmonic nanolaser. This paper advances the understanding of lasing emission behavior in plasmonic nanolasers and paves the way for intentionally manipulating their emission for various applications of on-chip nanophotonic circuits, nonlinear nanophotonics, sensing, and imaging.