235 research outputs found
Graphene microheater for phase change chalcogenides based integrated photonic components [Invited]
No full textIn order to effectively control the state of an active integrated photonic component based on chalcogenide phase change materials, an efficient microheater operating at low voltage is required. Here, we report on the design of a graphene based microheater. The proposed system contains two separate graphene layers between which the phase change material cell of Ge2Sb2Te5 is placed. Three distinct switching possibilities are explored, using only the bottom layer, only the top layer or both graphene layers. A detailed investigation of the heater parameters is performed to optimise switching performance. A self-consistent multiphysics simulation of the crystallization process in the phase change material cell is conducted demonstrating the switching capabilities of the proposed design
Slowing and stopping light using an optomechanical crystal array
Get PDFOne of the major advances needed to realize all-optical information
processing of light is the ability to delay or coherently store and retrieve optical
information in a rapidly tunable manner. In the classical domain, this optical
buffering is expected to be a key ingredient of managing the flow of information
over complex optical networks. Such a system also has profound implications for
quantum information processing, serving as a long-term memory that can store
the full quantum information contained in an optical pulse. Here, we suggest a
novel approach to light storage involving an optical waveguide coupled to an
optomechanical crystal array, where light in the waveguide can be dynamically
and coherently transferred into long-lived mechanical vibrations of the array.
Under realistic conditions, this system is capable of achieving large bandwidths
and storage/delay times in a compact, on-chip platform
Optical sculpting:shaping the future of Biophotonics
No full textWe describe the topic of beam shaping (sculpting) the phase and amplitude of light for applications in Biophotonics. Methods to create and apply 'non-diffracting' modes in cell transfection and micromanipulation will be discussed as well as a new method to correct for aberrations in situ and overcome the diffraction limit.</p
Graphene Plasmonics
Get PDFPlasmons in doped graphene provide an ideal platform for strong light‐matter interaction, perfect light absorption in an atomically thin layer, and ultra‐large field enhancement, well beyond conventional plasmonics, and tunable through electrostatic doping
FDTD Modeling of Nano- and Bio-Photonic Imaging
No full textIn this paper we focus on the discussion of two recent unique applications of the Finite-Difference Time-Domain (FDTD) simulation method to the design and modeling of advanced nano- and bio-photonic problems. The approach that is adopted here focuses on the potential of the FDTD methodology to address newly emerging problems and not so much on its mathematical formulation. We will first discuss the application of a traditional formulation of the FDTD approach to the modeling of sub-wavelength photonics structures. Next, a modified total/scattered field FDTD approach will be applied to the modeling of biophotonics applications including Optical Phase Contrast Microscope (OPCM) imaging of cells containing gold nanoparticles (NPs) as well as its potential application as a modality for in vivo flow cytometry configurations
FDTD Modeling of Nano- and Bio-Photonic Imaging
No full textIn this paper we focus on the discussion of two recent unique applications of the Finite-Difference Time-Domain (FDTD) simulation method to the design and modeling of advanced nano- and bio-photonic problems. The approach that is adopted here focuses on the potential of the FDTD methodology to address newly emerging problems and not so much on its mathematical formulation. We will first discuss the application of a traditional formulation of the FDTD approach to the modeling of sub-wavelength photonics structures. Next, a modified total/scattered field FDTD approach will be applied to the modeling of biophotonics applications including Optical Phase Contrast Microscope (OPCM) imaging of cells containing gold nanoparticles (NPs) as well as its potential application as a modality for in vivo flow cytometry configurations
Generation of ultrashort pulses via self-pulsations in coupled nonlinear microcavities
No full textThe energy exchange between coupled microcavities is shown to counteract the switching process, giving rise to self-pulsations. A nonlinear photonic crystal with two artificially placed defects is proposed as a representative example of such system. The coupled-mode equations are applied to describe its dynamical properties and to analyze the stability of solutions obtained by the transfer matrix method. Here we show how to control the parameters of the system in order to design a device that converts continuous waves into very regular and ultrashort pulses.</p
Instabilities and solitons in nonlinear excitonic waveguides
No full textThe propagation of light in a single-mode micron-size waveguide made of semiconducting excitonic material has been studied both analytically and numerically. The light pulses, spectrally centered in the vicinity of the 1s Wannier exciton resonance, interact with the medium nonlinearly. This optical cubic nonlinearity is caused by the repulsive exciton-exciton interactions in the semiconductor. We demonstrate that a very strong, unconventional modulational instability takes place, which has not been reported before. After reducing the coupled ordinary differential equation for the medium polarization and Maxwell's equations for the light pulse to a single nonlinear Schrodinger equation, we are also able to explore the formation of solitary waves both inside and outside the polaritonic gap.</p
Numerical investigation of passive optical sorting of plasmon nanoparticles
No full textFunding: UK Engineering and Physical Sciences Research Council for funding, KD is a Royal Society-Wolfson Merit Award Holder.We explore the passive optical sorting of plasmon nanoparticles and investigate the optimal wavelength and optimal beam shape of incident field. The condition for optimal wavelength is found by maximising the nanoparticle separation whilst minimising the temperature increase in the system. We then use the force optical eigenmode (FOEi) method to find the beam shape of incident electromagnetic field, maximising the force difference between plasmon nanoparticles. The maximum force difference is found with respect to the whole sorting region. The combination of wavelength and beam shape study is demonstrated for a specific case of gold nanoparticles of radius 40 nm and 50 nm respectively. The optimum wavelength for this particular situation is found to be above 700 nm. The optimum beam shape depends upon the size of sorting region and ranges from plane-wave illumination for infinite sorting region to a field maximising gradient force difference in a single point. (C) 2011 Optical Society of AmericaPeer reviewe
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