Solid-state single photon sources: the nanowire antenna

Abstract

We design several single-photon-sources based on the emission of a quantum dot embedded in a semiconductor (GaAs) nanowire. Through various taper designs, we engineer the nanowire ends to realize efficient metallic-dielectric mirrors and to reduce the divergence of the far-field radiation diagram. Using fully-vectorial calculations and a comprehensive Fabry-Perot model, we show that various realistic nanowire geometries may act as nanoantennas (volume of approximately 0.05 lambda(3)) that assist funnelling the emitted photons into a single monomode channel. Typically, very high extraction efficiencies above 90% are predicted for a collection optics with a numerical aperture NA=0.85. In addition, since no frequency-selective effect is used in our design, this large efficiency is achieved over a remarkably broad spectral range, Deltalambda=70 nm at lambda=950 nm.

How much better are InGaN/GaN nanodisks than quantum wells—Oscillator strength enhancement and changes in optical properties

“…A similar trend in η col has been predicted for a dipole emitter embedded near the end of a semi-infinite dielectric nanowire 15,34 . It was shown that 34 , for a large nanopillar, most light is coupled into two guided HE 11 modes, one propagating upwards and the other downwards into the substrate. However, the upwards-propagating guided mode is mostly reflected back into the substrate by the top facet of the nanopillar.…”

Coherent Interaction of Light and Single Molecules in a Dielectric Nanoguide

“…This point of view invokes an alternative strategy for optimizing light-matter coupling efficiency: one can modify the spatial mode of the atomic radiation to match the profile of the incident light beam, e.g., by employing parabolic [19] or planar [20] antennas. Similarly, it has been shown that a dielectric fiber with a subwavelength diameter can also channel the emission of an atom into its fundamental guiding mode [21,22] we generally refer to such a subwavelength waveguide antenna as a "nanoguide. "…”

“…Interestingly, discussions of nanoguides have emerged somewhat in parallel to the tight focusing approach in different theoretical treatments [21][22][23][24] and experimental studies of glass nanofibers [25][26][27], plasmonic nanowires [28], photonic crystal waveguides [29,30], and even microwave transmission lines [31]. Moreover, scientists have investigated nonlinear optical effects in hollow-core fibers [32,33], although the mode in these structures is considerably less confined than in a nanoguide.…”

Nanowire Waveguides Launching Single Photons in a Gaussian Mode for Ideal Fiber Coupling

“…10 At optimum waveguide conditions, the quantum dot emission is guided along the nanowire, adiabatically transferred to the far field and the larger fraction of this light is collected at small angles. In contrast, the emission of a dipole oriented along the nanowire axis couples very poorly to the fundamental waveguide mode.…”