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Creating a switchable optical cavity with controllable quantum-state mapping between two modes
摘要： We describe how an ensemble of four-level atoms in the diamond-type configuration can be applied to create a fully controllable effective coupling between two cavity modes. The diamond-type configuration allows one to use a bimodal cavity that supports modes of different frequencies or different circular polarisations, because each mode is coupled only to its own transition. This system can be used for mapping a quantum state of one cavity mode onto the other mode on demand. Additionally, it can serve as a fast opening high-Q cavity system that can be easily and coherently controlled with laser fields.
关键词： cavity modes,diamond-type configuration,high-Q cavity,laser fields,quantum state mapping
更新于2025-09-23 15:21:01
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Tuning Plasmonic Coupling from Capacitive to Conductive Regimes via Atomic Control of Dielectric Spacing
摘要： The gap length between plasmonic nanoparticles determines the strength of the optical coupling that results in electromagnetic field enhancement for spectroscopic and other applications. Although gap plasmon resonances have been the focus of increasing research interest, experimental observations have primarily been limited to the coupling of spherical nanoparticles that may not provide clear spectral contrast of the optical response as the interaction evolves from capacitive to charge transfer with the gap size decreasing to subnanometer. Here, by taking advantage of the sharp plasmon resonances of colloidal gold nanorods coupled to gold film, we present the spectral evolution of gap plasmon resonance as the particle-film spacing varies from over 30 nm to the touching limit. We find that, the capacitive gap plasmon resonance of the coupled system red shifts and narrows continuously until it vanishes at the quantum tunneling limit, in contrast to the nonlocal and Landau damping effects that are expected to result in relative blue shifting and spectral broadening. When the spacer thickness is further decreased, high order cavity modes appear, and eventually single peak broad resonances that are characteristic of tunneling and direct contact particle-film interaction emerge. The experimental observations show that nanorods are better suited for creating cavity plasmon resonances with high quality factor, and the spectral contrast at the transition provides clarity to develop improved theoretical modeling of optical coupling at subnanometer gap lengths.
关键词： atomic layer deposition,tunneling,plasmon coupling,Particle on metal film,cavity modes,charge transfer,gold nanorods
更新于2025-09-23 15:19:57
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Sn-doped CdS Nanowires with Low Temperature Lasing by CW-Laser Excitation
摘要： Sn-doped CdS nanowires, with the inside coexisting Sn(II)S, Sn2(III)S3 and Sn(IV)S2 identified by in situ Raman and XPS spectra, are grown via a simple thermal evaporation deposition technique. Its room-temperature photoluminescence (PL) spectrum shows a broad ingap emission band out of different Sn dopants which is also superposed by a series of weak modes from a microcavity due to the wire size and its structure, besides the CdS bandedge emission and a sideband emission due to SnS2. The ratio of the intensity of the ingap emission versus that of the bandedge emission is only 1/4 at room temperature, but it can be remarkably increased to about 7 at 80K. This significant enhancement of the ingap emission may be attributed to the local plasma coming from more bound carriers and enhanced microcavity effect at low temperature by analyzing the temperature-dependent PL and Raman spectra in detail. For these reasons, the bandedge and ingap emission both can realize lasing excitated by a continuous laser at 80K. The results would provide a way to get temperature tunable low threshold microscale lasers and study the plasma-polariton process within microcavity.
关键词： Sn-doped nanowires,plasma,cavity modes,lasing,coupled cavity
更新于2025-09-12 10:27:22