36 research outputs found
Generation and quantum control of giant plasmon pulses by transient quantum coherence
Amplified ultrashort laser pulses are useful in many fields of science and
engineering. Pushing the frontiers of ultrashort pulse generation will lead to
new applications in biomedical imaging, communications and sensing. We propose
a new, quantum approach to ultrashort pulse generation using transient quantum
coherence which predicts order of magnitude stronger pulses generated with
lower input energy than in the steady-state regime, reducing the practical
heating limitations. This femtosecond quantum-coherent analog of nanosecond
Q-switching is not limited by the pulse duration constraints of the latter,
and, in principle, may be used for a variety of lasers including x-ray and
plasmon nanolasers. We apply this approach to generation of giant plasmon
pulses and achieve quantum control of plasmon relaxation dynamics by varying
the drive pulse delay, amplitude and duration. We provide insights into the
control mechanisms, and discuss future implementations and applications of this
new source of ultrashort nanooptical fields
Quantum-Coherence-Enhanced Surface Plasmon Amplification by Stimulated Emission of Radiation
We investigate surface plasmon amplification in a silver nanoparticle coupled
to an externally driven three-level gain medium, and show that quantum
coherence significantly enhances the generation of surface plasmons. Surface
plasmon amplification by stimulated emission of radiation is achieved in the
absence of population inversion on the spasing transition, which reduces the
pump requirements. The coherent drive allows us to control the dynamics, and
holds promise for quantum control of nanoplasmonic devices.Comment: 5 pages, 4 figure
Quantum plasmonic hot-electron injection in lateral WSe2/MoSe2 heterostructures
Lateral two-dimensional (2D) transitional metal dichalcogenide (TMD)
heterostructures have recently attracted a wide attention as promising
materials for optoelectronic nanodevices. Due to the nanoscale width of lateral
heterojunctions, the study of their optical properties is challenging and
requires using subwavelength optical characterization techniques. We
investigated the photoresponse of a lateral 2D WSe2/MoSe2 heterostructure using
tip-enhanced photoluminescence (TEPL) with nanoscale spatial resolution and
with picoscale tip-sample distance dependence. We demonstrate the observation
of quantum plasmonic effects in 2D heterostructures on a non-metallic
substrate, and we report the nano-optical measurements of the lateral 2D TMD
heterojunction width of ~ 150 nm and the charge tunneling distance of ~ 20 pm.
Controlling the plasmonic tip location allows for both nano-optical imaging and
plasmon-induced hot electron injection into the heterostructure. By adjusting
the tip-sample distance, we demonstrated the controllability of the
hot-electron injection via the competition of two quantum plasmonic
photoluminescence (PL) enhancement and quenching mechanisms. The directional
charge transport in the depletion region leads to the increased hot electron
injection, enhancing the MoSe2 PL signal. The properties of the directional
hot-electron injection in the quantum plasmonic regime make the lateral 2D
MoSe2/WSe2 heterostructures promising for quantum nanodevices with tunable
photoresponse