arXiv subjects

Lanyin Luo

Publications and source records attributed to Lanyin Luo.

3 recordsLinked to original sources

arXiv2026

Purcell-enhanced Bright and Dark Exciton Emission from Perovskite Quantum Dots in Micro-ring Resonators

Colloidal quantum dots (QDs) integrated with waveguide-coupled dielectric resonators are promising building blocks for compact on-chip light sources. However, deterministic placement of QDs with strong mode overlap at the desired location remains a challenge. Here, we demonstrate a simple and scalable strategy for integrating colloidal QDs with a waveguide-coupled Si3N4 micro-ring resonator platform and for controlling the radiative dynamics of both bright and dark excitons via Purcell enhancement. We use strongly quantum-confined CsPbBr3 QDs, which exhibit bright-exciton emission at room-temperature, while emission at cryogenic temperatures originates from both bright and dark excitons. The CsPbBr3 QDs are selectively retained on the Si3N4 micro-ring cavities through a spin-coating/rinsing process, enabling efficient overlap with whispering-gallery modes and routing of the emission through integrated waveguides. We confirm accelerated decay of emission from both bright and dark excitons for CsPbBr3 QDs coupled to the micro-ring cavities. These results demonstrate an effective route to integrate colloidal QDs with Si3N4 micro-ring cavities and to leverage cavity-enhanced emission in scalable integrated photonic devices.

physics.optics↗

arXiv2024

Polarized Superradiance from CsPbBr3 Quantum Dot Superlattice with Controlled Inter-dot Electronic Coupling

Cooperative emission of photons from an ensemble of quantum dots (QDs) as superradiance can arise from the electronically coupled QDs with a coherent emitting excited state. This contrasts with superfluorescence (Dicke superradiance), where the cooperative photon emission occurs via a spontaneous buildup of coherence in an ensemble of incoherently excited QDs via their coupling to a common radiation mode. While superfluorescence has been observed in perovskite QD systems, reports of superradiance from the electronically coupled ensemble of perovskite QDs are rare. Here, we demonstrate the generation of polarized superradiance with a very narrow linewidth (<5 meV) and a large redshift (~200 meV) from the electronically coupled CsPbBr3 QD superlattice achieved through a combination of strong quantum confinement and ligand engineering. In addition to photon bunching at low excitation densities, the superradiance is polarized in contrast to the uncoupled exciton emission from the same superlattice. This finding suggests the potential for obtaining polarized cooperative photon emission via anisotropic electronic coupling in QD superlattices even when the intrinsic anisotropy of exciton transition in individual QDs is weak.

cond-mat.mes-hall↗

arXiv2024

Characterization of resonator using confocal laser scanning microscopy and its application in air density sensing

We present the characterization of the photonic waveguide resonator using confocal laser scanning microscopy imaging method. Free space TEM$_{00}$ laser mode is coupled into quasi-TE$_{0}$ waveguide mode using confocal microscopy via a diffractive grating coupler and vice versa. Our work includes the design, fabrication, and experimental characterization of a silicon nitride racetrack-shaped resonator of length ~ 165 um. We illustrate clear evidence of resonance excitation from the confocal microscope image and demonstrate loaded Q-factor and finesse ~ 8.2 \pm 0.17 * 10^4 and ~ 180 \pm 3.5, respectively. We further demonstrate its one application in air density sensing by measuring the resonance wavelength shifts with variation in environment air pressure. Our work impacts spectroscopy, imaging, and sensing applications of single or ensemble atoms or molecules coupled to photonic devices. Additionally, our study highlights the potential of confocal microscopy for analyzing photonic components on large-scale integrated circuits, providing high-resolution imaging and spectral characterization.

physics.optics↗