From vertical-cavities to hybrid metal/photonic-crystal nanocavities: towards high-efficiency nanolasers

Abstract

We provide a numerical study showing that a bottom reflector is indispensable to achieve unidirectional emission from a photonic-crystal (PhC) nanolaser. First, we study a PhC slab nanocavity suspended over a flat mirror formed by a dielectric or metal substrate. We find that the laser's vertical emission can be enhanced by more than a factor of 6 compared with the device in the absence of the mirror. Then, we study the situation where the PhC nanocavity is in contact with a flat metal surface. The underlying metal substrate may serve as both an electrical current pathway and a heat sink, which would help achieve continuous-wave lasing operation at room temperature. The design of the laser emitting at 1.3 μm reveals that a relatively high cavity Q of over 1000 is achievable assuming room-temperature gold as a substrate. Furthermore, linearly polarized unidirectional vertical emission with the radiation efficiency over 50% can be achieved. Finally, we discuss how this hybrid design relates to various plasmonic cavities and propose a useful quantitative measure of the degree of the "plasmonic" character in a general metallic nanocavity.

Sandwich-typed resonator cavity based on a regular photonic crystal nanobeam

“…The second component of the structure (supplementary material) can be doped with ions and, thus, be used as the basis for one (top) of the contact pads. The other (bottom) contact pad may be implemented, for example, by using the approach described in [18]. In this case, the bottom reflector may serve as both an electrical current pathway and a heat sink.…”

Engineering of metal-clad optical nanocavity to optimize coupling with integrated waveguides

“…However, because of the optical diffraction limit, further reducing the size of conventional III-V components does not generate the expected advantages [12]. To overcome this limitation, researchers have recently explored metallic III-V nanoscale optical cavities and achieved physical and modal sizes on the subwavelength scale, which is sufficiently small to open up new possibilities for implementing higher-performing Si/III-V hybrid optical systems [13][14][15][16][17][18][19][20][21][22][23][24][25]. However, with this approach, one significant problem in practical integration and use arises: Because of the extremely small output aperture of such a cavity, the radiation from the cavity diverges very rapidly, which makes optical coupling between the III-V cavity and integrated Si-waveguides very inefficient [25,26].…”

The design criteria of hybrid waveguides using semiconductor gain to compensate the metal loss towards nano-scale lasers with high plasmonicity

“…The ideal case means the operation wavelength of lasing is the same as the SP resonance, i.e., plasmonicity H ¼ x=x sp is unity. 25,26 In order to understand how plasmonicity affects the thresholds (and modal loss) in active devices, we consider a simple example of single semi-infinite Ag/GaN interface. The complex permittivity of Ag is taken from Johnson and Christy's (J&C) data 27 unless otherwise stated, and the permittivity of GaN is taken from Ref.…”