Dielectric slotted nanodisk laser with ultralow pump threshold by anapole excitation

Developing ultralow threshold nanolasers is a challenging task despite of their great potential for a variety of applications. This work proposes to combine the advantages of low loss of dielectric materials and tight confinement of field in slotted dielectric nanodisks with gain medium embedded to them and supported by metallic substrate, which generates anapole mode with a lifetime longer than for dielectric substrate. Since the dielectric nanocavity has intrinsically low loss, one can achieve lasing with ultralow threshold down to 0.02 pJ for a spot size 1.5 μm of pump, several orders-of-magnitude lower than the preceding records. Dielectric slotted disk nanolasers proposed here can find broad applications for biosensing, near-field spectroscopy, and many other fields.