3 research outputs found
Direct On-Chip Optical Plasmon Detection with an Atomically Thin Semiconductor
The determination to develop fast,
efficient devices has led to vast studies on photonic circuits but
it is difficult to shrink these circuits below the diffraction limit
of light. However, the coupling between surface plasmon polaritons
and nanostructures in the near-field shows promise in developing next-generation
integrated circuitry. In this work, we demonstrate the potential for
integrating nanoplasmonic-based light guides with atomically thin
materials for on-chip near-field plasmon detection. Specifically,
we show near-field electrical detection of silver nanowire plasmons
with the atomically thin semiconductor molybdenum disulfide. Unlike
graphene, atomically thin semiconductors such as molybdenum disulfide
exhibit a bandgap that lends itself for the excitation and detection
of plasmons. Our fully integrated plasmon detector exhibits plasmon
responsivities of ∼255 mA/W that corresponds to highly efficient
plasmon detection (∼0.5 electrons per plasmon)
Quantum-Confined Stark Effect of Individual Defects in a van der Waals Heterostructure
The
optical properties of atomically thin semiconductor materials have
been widely studied because of the isolation of monolayer transition
metal dichalcogenides (TMDCs). They have rich optoelectronic properties
owing to their large direct bandgap, the interplay between the spin
and the valley degree of freedom of charge carriers, and the recently
discovered localized excitonic states giving rise to single photon
emission. In this Letter, we study the quantum-confined Stark effect
of these localized emitters present near the edges of monolayer tungsten
diselenide (WSe<sub>2</sub>). By carefully designing sequences of
metallic (graphene), insulating (hexagonal boron nitride), and semiconducting
(WSe<sub>2</sub>) two-dimensional materials, we fabricate a van der
Waals heterostructure field effect device with WSe<sub>2</sub> hosting
quantum emitters that is responsive to external static electric field
applied to the device. A very efficient spectral tunability up to
21 meV is demonstrated. Further, evaluation of the spectral shift
in the photoluminescence signal as a function of the applied voltage
enables us to extract the polarizability volume (up to 2000 Ã…<sup>3</sup>) as well as information on the dipole moment of an individual
emitter. The Stark shift can be further modulated on application of
an external magnetic field, where we observe a flip in the sign of
dipole moment possibly due to rearrangement of the position of electron
and hole wave functions within the emitter
Nanoscale Fluorescence Lifetime Imaging of an Optical Antenna with a Single Diamond NV Center
Solid-state quantum emitters, such
as artificially engineered quantum
dots or naturally occurring defects in solids, are being investigated
for applications ranging from quantum information science and optoelectronics
to biomedical imaging. Recently, these same systems have also been
studied from the perspective of nanoscale metrology. In this letter,
we study the near-field optical properties of a diamond nanocrystal
hosting a single nitrogen vacancy center. We find that the nitrogen
vacancy center is a sensitive probe of the surrounding electromagnetic
mode structure. We exploit this sensitivity to demonstrate nanoscale
fluorescence lifetime imaging microscopy (FLIM) with a single nitrogen
vacancy center by imaging the local density of states of an optical
antenna