19 research outputs found
Emergence Of Directional Rotation In Optothermally Activated Colloidal System
We experimentally demonstrate the emergence of directional rotation in
thermally active-passive colloidal structures under optical confinement. The
observed handedness of rotation of the structure can be controlled by changing
the relative position of the constituent colloids. We show that the angular
velocity of rotation is sensitive to the intensity of the incident optical
fields and the size of the constituent colloidal entities. The emergence of
rotational dynamics can be understood in the context of asymmetric temperature
distribution in the system and the relative location of the active colloid,
which creates a local imbalance of optothermal torques to the confined system.
Our work demonstrates how localized optothermal fields lead to directional
rotational dynamics without explicitly utilizing spin or orbital angular
momentum of light. We envisage that our results will have implications in
realizing Brownian engines, and can directly relate to rotational dynamics in
biological and ecological systems
Directional emission from WS2 monolayer coupled to plasmonic Nanowire-on-Mirror Cavity
Influencing spectral and directional features of exciton emission
characteristics from 2D transition metal dichalcogenides by coupling it to
plasmonic nano-cavities has emerged as an important prospect in nanophotonics
of 2D materials. In this paper we experimentally study the directional
photoluminescence emission from Tungsten disulfide (WS2) monolayer sandwiched
between a single-crystalline plasmonic silver nanowire (AgNW) waveguide and a
gold (Au) mirror, thus forming an AgNW-WS2-Au cavity. By employing
polarization-resolved Fourier plane optical microscopy, we quantify the
directional emission characteristics from the distal end of the AgNW-WS2-Au
cavity. Given that our geometry simultaneously facilitates local field
enhancement and waveguiding capability, we envisage its utility in 2D
material-based, on-chip nanophotonic signal processing, including nonlinear and
quantum optical regimes.Comment: To appear in Advanced Photonics Research (2021
Mirror-Coupled Microsphere can narrow the Angular distribution of Photoluminescence from WS2 Monolayers
Engineering optical emission from two dimensional, transition metal
dichalcogenides (TMDs) materials such as Tungsten disulphide (WS2) has
implications in creating and understanding nanophotonic sources. One of the
challenges in controlling the optical emission from 2D materials is to achieve
narrow angular spread using a simple photonic geometry. In this paper, we study
how the photoluminescence of a monolayer WS2 can be controlled when coupled to
film coupled microsphere dielectric antenna. Specifically, by employing Fourier
plane microscopy and spectroscopic techniques, we quantify the wavevector
distribution in the momentum space. As a result, we show beaming of the WS2
photoluminescence with angular divergence of {\theta}1/2 = 4.6{\deg}.
Furthermore, the experimental measurements have been supported by
three-dimensional numerical simulations. We envisage that the discussed results
can be generalized to a variety of nanophotonic 2D materials, and can be
harnessed in nonlinear and quantum technology
Optothermal Evolution of Active Colloidal Matter in a Defocused Laser Trap
Optothermal interaction of active colloidal matter can
facilitate
environmental cues, which can influence the dynamics of active soft
matter systems. The optically induced thermal effect can be harnessed
to study non-equilibrium thermodynamics as well as applied to self-propel
colloids and form assemblies. In this work, we employ a defocused
laser trap to form self-evolving colloidal active matter. The optothermal
interaction of the active colloids in both focused and defocused optical
traps has been investigated to ascertain their thermophoretic behavior,
which shows a long-range attraction and a short-range repulsion between
the colloids. The optical gradient field-enabled attraction and the
short-range repulsion between the active colloids have been harnessed
to form a re-configurable dynamic assembly. Additionally, the assembly
undergoes self-evolution as a new colloid joins the structure. Further,
we show that the incident polarization state of the optical field
can be employed as a parameter to modulate the structural orientation
of the active colloids. The simple defocused optical field-enabled
assembly can serve as a model to understand the collective dynamics
of active matter systems and can be harnessed as a re-configurable
microscopic engine
Optothermal Evolution of Active Colloidal Matter in a Defocused Laser Trap
Optothermal interaction of active colloidal matter can
facilitate
environmental cues, which can influence the dynamics of active soft
matter systems. The optically induced thermal effect can be harnessed
to study non-equilibrium thermodynamics as well as applied to self-propel
colloids and form assemblies. In this work, we employ a defocused
laser trap to form self-evolving colloidal active matter. The optothermal
interaction of the active colloids in both focused and defocused optical
traps has been investigated to ascertain their thermophoretic behavior,
which shows a long-range attraction and a short-range repulsion between
the colloids. The optical gradient field-enabled attraction and the
short-range repulsion between the active colloids have been harnessed
to form a re-configurable dynamic assembly. Additionally, the assembly
undergoes self-evolution as a new colloid joins the structure. Further,
we show that the incident polarization state of the optical field
can be employed as a parameter to modulate the structural orientation
of the active colloids. The simple defocused optical field-enabled
assembly can serve as a model to understand the collective dynamics
of active matter systems and can be harnessed as a re-configurable
microscopic engine
Optothermal Evolution of Active Colloidal Matter in a Defocused Laser Trap
Optothermal interaction of active colloidal matter can
facilitate
environmental cues, which can influence the dynamics of active soft
matter systems. The optically induced thermal effect can be harnessed
to study non-equilibrium thermodynamics as well as applied to self-propel
colloids and form assemblies. In this work, we employ a defocused
laser trap to form self-evolving colloidal active matter. The optothermal
interaction of the active colloids in both focused and defocused optical
traps has been investigated to ascertain their thermophoretic behavior,
which shows a long-range attraction and a short-range repulsion between
the colloids. The optical gradient field-enabled attraction and the
short-range repulsion between the active colloids have been harnessed
to form a re-configurable dynamic assembly. Additionally, the assembly
undergoes self-evolution as a new colloid joins the structure. Further,
we show that the incident polarization state of the optical field
can be employed as a parameter to modulate the structural orientation
of the active colloids. The simple defocused optical field-enabled
assembly can serve as a model to understand the collective dynamics
of active matter systems and can be harnessed as a re-configurable
microscopic engine
Optothermal Evolution of Active Colloidal Matter in a Defocused Laser Trap
Optothermal interaction of active colloidal matter can
facilitate
environmental cues, which can influence the dynamics of active soft
matter systems. The optically induced thermal effect can be harnessed
to study non-equilibrium thermodynamics as well as applied to self-propel
colloids and form assemblies. In this work, we employ a defocused
laser trap to form self-evolving colloidal active matter. The optothermal
interaction of the active colloids in both focused and defocused optical
traps has been investigated to ascertain their thermophoretic behavior,
which shows a long-range attraction and a short-range repulsion between
the colloids. The optical gradient field-enabled attraction and the
short-range repulsion between the active colloids have been harnessed
to form a re-configurable dynamic assembly. Additionally, the assembly
undergoes self-evolution as a new colloid joins the structure. Further,
we show that the incident polarization state of the optical field
can be employed as a parameter to modulate the structural orientation
of the active colloids. The simple defocused optical field-enabled
assembly can serve as a model to understand the collective dynamics
of active matter systems and can be harnessed as a re-configurable
microscopic engine