Design of plasmon cavities for solid-state cavity quantum electrodynamics applications

Abstract

Research on photonic cavities with low mode volume and high quality factor garners much attention because of applications ranging from optoelectronics to cavity quantum electrodynamics (QED). We propose a cavity based on surface plasmon modes confined by metallic distributed Bragg reflectors. We analyze the structure with Finite Difference Time Domain simulations and obtain modes with quality factor 1000 (including losses from metals at low temperatures), reduced mode volume relative to photonic crystal cavities, Purcell enhancements of hundreds, and even the capability of enabling cavity QED strong coupling.The modification of the spontaneous emission (SE) rate of emitters has been a pressing topic in recent research.By enhancing or suppressing emission, we could increase the efficiencies of photon sources, reduce laser threshold, and tailor sources for cavity cavity quantum electrodynamics (QED) applications such as quantum computation and quantum communications. Some researchers have demonstrated the enhancement of emission rates (Purcell effect) in solid-state by modifying the local density of optical states with photonic crystal (PC) cavities [1]. However, such works face limitations in the mode volume of the cavity. One implementation that could produce smaller mode volumes, and hence higher Purcell factors, is the use of surface plasmon (SP) modes. Already, there have been reports of enhancement of photoluminesence by coupling emitters to regions of high SP density of states (DOS) [2]. Moreover, another group has proposed coupling emitters to metallic nanowires and nanotips to enhance Purcell factors [3]. By employing SP cavities in solid-state, we could attempt to achieve the same or even higher SE rate enhancement as with previous designs, but with simplified fabrication.Several authors have demonstrated decreased transmission by using periodic structures to manipulate SPs [4,5].These experiments confirm the existence of backscattering and a plasmonic band gap in metallic gratings. In addition, other groups have demonstrated that surface plasmons interfere as normal waves and set up standing waves under certain conditions [6]. Given such properties, it is easy to conceive of a cavity that is the marriage of the previous two devices, a cavity that contains the electromagnetic field of the plasmon mode with metallic distributed Bragg reflector (DBR) gratings on either side of the cavity. While some plasmonic DBR cavities have been proposed in previous works [6,7], the designs are often impractical to fabricate.

Exciton-plasmon coupling interactions: from principle to applications

“…The existence of the decoherent mechanism can make the energy exchange between the atoms and the magnetic field weaker until it disappears. Nowadays, researchers seek a variety of ways to reduce the influence of cavity EM such as reducing the volume [99], coating [100], and superconductivity of cavity [101] to increase the coherence interaction intensity. When this coherent mechanism is dominated rather than the decoherent mechanism, we usually called it the strong coupling.…”

Plasmonic band gap cavities on biharmonic gratings

“…[16][17][18] Theoretical approaches show that propagating SPPs can also be localized through the use of a properly designed cavity that supports these modes. 19 Very recently, progress in the theoretical analysis of such cavities has been confirmed with the demonstration of a grating based cavity using Bragg mirrors. 17 Unfortunately, this approach just allows the mapping of the electric field distribution through the cavity.…”

“…This quality factor is relatively low for plasmonic cavities as compared to photonic crystal cavities. The overall quality factor can be described as 19 1…”

“…The induced effective index contrast between the cavity and its surroundings results in the localization of propagating modes, 20 much like those that are supported by Bragg mirrors. 17,19,21,22 Additionally, our approach allows to extract extensive information on the band structure of the cavity and the dispersion of the cavity state in a very simple way for both preparation and characterization of the cavity structure.…”

Subwavelength metallic cavities with high-Qresonance modes

“…Metal absorption loss is due to electron-phonon and electron-electron scattering in metals and is suppressed at low temperature [28]. Therefore Q factors of SPP cavity modes exhibit highly temperature-dependent properties [12][13][14][15]. Optical radiation loss occurs in dielectric cavities due to optical-field extension outside cavities [29].…”