Second-harmonic generation enhancement in high-contrast micropillar AlGaAs resonator in bound states in the continuum regime

It has been shown that the use of micropillar resonators, which comprise a cylindrical semiconductor cavity sandwiched between the Bragg mirrors can substantially increase the quality factor preserving the mode volume, and thus substantially enhance the local fields. Here, we show that these structures indeed can facilitate the significant enhancement of the SHG efficiency. We provide a specific design of the AlGaAs pillar microcavity and use the numerical modelling to directly show the resonant enhancement of the SHG efficiency. We believe that the presented results would be of high interest to the nanophotonic community, especially in nonlinear optics field.

Plasmonic nanolasers: fundamental properties and applications

Plasmonic nanolasers are a new class of coherent emitters where surface plasmons are amplified by stimulated emission in a plasmonic nanocavity. In contrast to lasers, the physical size and mode volume of plasmonic nanolasers can shrink beyond the optical diffraction limit, and can be operated with faster speed and lower power consumption. It was initially proposed by Bergman and Stockman in 2003, and first experimentally demonstrated in 2009. Here we summarize our studies on the fundamental properties and applications of plasmonic nanolasers in recent years, including dark emission characterization, scaling laws, quantum efficiency, quantum threshold, gain and loss optimization, low loss plasmonic materials, sensing, and eigenmode engineering.

Nanometer-scale photon confinement inside dielectrics

Optical nanocavities confine and store light, which is essential to increase the interaction between photons and electrons in semiconductor devices, enabling, e.g., lasers and emerging quantum technologies. While temporal confinement has improved by orders of magnitude over the past decades, spatial confinement inside dielectrics was until recently believed to be bounded at the diffraction limit. The conception of dielectric bowtie cavities (DBCs) shows a path to photon confinement inside semiconductors with mode volumes bound only by the constraints of materials and nanofabrication, but theory was so far misguided by inconsistent definitions of the mode volume and experimental progress has been impeded by steep nanofabrication requirements. Here we demonstrate nanometer-scale photon confinement inside 8 nm silicon DBCs with an aspect ratio of 30, inversely designed by fabrication-constrained topology optimization. Our cavities are defined within a compact device footprint of 4 lambda^2 and exhibit mode volumes down to V = 3E-4 lambda^3 with wavelengths in the lambda = 1550 nm telecom band. This corresponds to field localization deep below the diffraction limit in a single hotspot inside the dielectric. A crucial insight underpinning our work is the identification of the critical role of lightning-rod effects at the surface. They invalidate the common definition of the mode volume, which is prone to gauge meretricious surface effects or numerical artefacts rather than robust confinement inside the dielectric. We use near-field optical measurements to corroborate the photon confinement to a single nanometer-scale hotspot. Our work enables new CMOS-compatible device concepts ranging from few- and single-photon nonlinearities over electronics-photonics integration to biosensing.

Nanopyramid With High Purity And Their Local Plasmonic Properties

Au nanopyramid particles (Au NBPs) are highly desirable for its remarkable optical properties such as long-range tunable resonance. It has wide applications in room-temperature bioimaging probes and bioanalytical sensors. In this paper, we synthesize Au NBPs with a purity of 95%, and obtain the optical response of Au NBP in near infrared regime. We find that Au NBPs have small mode volume of electric field which can lead to the strong coupling with quantum dots at room temperature. It provides novel applications for Au NBPs in fields of materials, biomedical science, and quantum information

Breaking the diffraction limit in absorption spectroscopy using upconverting nanoparticles

We employ a single optically trapped upconverting nanoparticle (UCNP) of NaYF$_4$:Yb,Er of diameter about 100 nm as a subdiffractive source to perform absorption spectroscopy. The experimentally expected mode volume of...