Abstract

Metallic and plasmonic nano-lasers are the latest stage in the miniaturization of lasers. The use of metals to form the optical cavity gives great freedom in the form and size of the cavity. Uniquely, cavities can be made where the light is confined to regions much smaller than the diffraction limit. Alternatively, larger cavities can be made where the confinement of light is less, though still strong in comparison to dielectric cavities, but the optical losses due to the metal are much smaller. A number of experiments performed by different groups have started to demonstrate some of the different forms of metallic cavity possible and also their remarkable properties [1-8]. The progress compared to that of other small lasers such as VCSELs or photonic crystal lasers has been stunning. In particular not only have many different forms of cavity been shown, but also there has been rapid progress from first demonstrations at cryogenic temperatures, to demonstrations at room temperature with electrical pumping. This is due to the fact that the noble metals used to form the cavities are excellent conductors of both electricity and heat. Thus many of the problems in other nano laser types involving heat sinking and electrical pumping can be solved by the intrinsic nature of the cavities themselves. Furthermore, in theory the construction of good mirrors to confine the light does not require complex nano-scale structures such as in dielectric Bragg mirrors. Finally, the small size and excellent heat sinking allow semiconductor gain materials to be pushed to their limits. Experiments have shown that optical material gains in the thousands per cm are possible in real devices, even at room temperature with electrical pumping [2,4,8].

© 2011 IEEE