Engineering topics

Wang, Weijia

Publications and source records attributed to Wang, Weijia.

7 records

DOE OSTI2020

Strongly Coupled Exciton–Surface Lattice Resonances Engineer Long-Range Energy Propagation

Achieving propagation lengths in hybrid plasmonic systems beyond typical values of tens of micrometers is important for quantum plasmonics applications. Iin this paper, we report long-range optical energy propagation due to excitons in semiconductor quantum dots (SQDs) being strongly coupled to surface lattice resonance (SLRs) in silver nanoparticle arrays. Photoluminescence (PL) measurements provide evidence of an exciton-SLR (ESLR) mode extending at least 600 mu m from the excitation region. We also observe additional energy propagation with range well beyond the ESLR mode and with dependency on the coupling strength, g, between SQDs and SLR. Cavity quantum electrodynamics calculations capture the nature of the PL spectra for consistent g values, while coupled dipole calculations show a SQD number-dependent electric field decay profile consistent with the experimental spatial PL profile. Our results suggest an exciting direction wherein SLRs mediate long-range interactions between SQDs, having possible applications in optoelectronics, sensing, and quantum information science.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2019

Engineering Symmetry-Breaking Nanocrescent Arrays for Nanolasing

This paper describes a symmetry-breaking plasmonic lattice structure that can support narrow resonances as optical feedback for nanolasing. A scalable technique is developed to fabricate nanocrescent arrays with low-structural symmetry unit cells to achieve in-plane quadrupolar lattice plasmon modes. These lattice plasmons with extremely narrow linewidths preserve nonzero net dipole moments under normal excitation. Ultrafast band-edge lasing can be switched on and off by changing the polarization of the incident pump light. In conclusion, the quadrupolar lattice plasmon lasing process is simulated with a semi-quantum model and the sharp tips on the nanocrescents accelerate the lasing buildup process and enhance stimulated emission.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Ultrafast Dynamics of Lattice Plasmon Lasers

Lattice plasmon cavity modes combined with optical gain can exhibit directional and tunable lasing emission at room temperature. However, the mechanistic details governing the dynamics before lasing action are not understood. Here, this paper describes how the long photon lifetimes of lattice plasmon modes can be correlated with the ultrafast dynamics of lasing action and amplified spontaneous emission. Lasing from band-edge plasmons and amplified spontaneous emission from propagating plasmons showed rise times on the order of tens of picoseconds, during which inverted population in the gain was first generated and then followed by energy transfer to the lattice plasmon cavity for enhanced light emission.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2019

Polarization-Dependent Lasing Behavior from Low-Symmetry Nanocavity Arrays

In this paper, we report how geometric effects in low-symmetry plasmonic nanoparticle arrays can produce polarization-dependent lasing responses. We developed a scalable fabrication procedure to pattern rhombohedral arrays of aluminum anisotropic nanoparticles that support lattice plasmon modes from both first-order and second-order diffraction coupling. We found that nanoparticle shape can be used to engineer the spatial overlap between electromagnetic hot spots of different lattice modes and dye gain to support plasmonic lasing. The lasing behavior revealed that plasmon–exciton energy transfer depends on polarization, with stronger coupling and faster dynamics when the transition dipole moments of the excited gain are aligned with the electric field of the plasmon modes.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Spatially defined molecular emitters coupled to plasmonic nanoparticle arrays

Significance The precise organization of molecular and functional nanoscale building blocks is a long-standing challenge in nanoscience. In particular, overlapping molecular emission with collective optical excitations at the nanoscale can result in exquisite control over the intensity, wavelength, and direction of emitted light. This work describes how positioning molecules that are components of a crystalline material called metal–organic frameworks (MOFs) around plasmonic nanoparticle arrays can result in strongly enhanced emission at wavelengths determined by the lattice, including the splitting of spectral bands by interference effects that do not require strong lattice–molecule coupling for their interpretation. This hybrid platform provides a framework for both spatially and temporally enhancing the properties of luminescent MOFs.

Liu, Jianxi↗

DOE OSTI2018

Stretchable Nanolasing from Hybrid Quadrupole Plasmons

This paper reports a robust and stretchable nanolaser platform that can preserve its high mode quality by exploiting hybrid quadrupole plasmons as an optical feedback mechanism. Increasing the size of metal nanoparticles in an array can introduce ultra-sharp lattice plasmon resonances with out-of-plane charge oscillations that are tolerant to lateral strain. By patterning these nanoparticles onto an elastomeric slab surrounded by liquid gain, we realized reversible, tunable nanolasing with high strain sensitivity and no hysteresis. Furthermore, our semi-quantum modeling demonstrates that lasing build-up occurs at the hybrid quadrupole electromagnetic hot spots, which provides a route towards mechanical modulation of light-matter interactions on the nanoscale.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2018

Roadmap on plasmonics

Explore the source record for details and available documents.

solar (photovoltaic), solid state lighting, phonon↗