We report on an integrated optical trapping platform operated by simple fiber coupling. The system consists of a dielectric channel optical waveguide decorated with an array of gold micro-pads. Through a suitable engineering of the waveguide mode, we achieve light coupling to the surface plasmon resonance of the gold pads that act as individual plasmonic traps. We demonstrate parallel trapping of both micrometer size polystyrene beads and yeast cells at predetermined locations on the chip with only 20 mW total incident laser power.
We study the optical properties of quantum dipole emitters coupled to hyperbolic metamaterial nano-resonators using a semi-analytical quasinormal mode approach. We show that coupling to metamaterial nano-resonators can lead to significant Purcell enhancements that are nearly an order of magnitude larger than those of plasmonic resonators with comparable geometry. However, the associated single photon output β-factors are extremely low (around 10%), far smaller than those of comparable sized metallic resonators (70%). Using a quasinormal mode expansion of the photon Green function, we describe how the low β-factors are due to increased Ohmic quenching arising from redshifted resonances, larger quality factors, and stronger confinement of light within the metal. In contrast to current wisdom, these results suggest that hyperbolic metamaterial nano-structures make poor choices for single photon sources. arXiv:1606.06957v2 [cond-mat.mes-hall]
Tm3+ doped silicon thin film and waveguides for mid-infrared sources Appl. Phys. Lett. 101, 141107 (2012) Record-low propagation losses of 154dB/cm for substrate-type W1 photonic crystal waveguides by means of hole shape engineering Appl. Phys. Lett. 101, 131108 (2012) Electro-optic polymer/TiO2 multilayer slot waveguide modulators Appl. Phys. Lett. 101, 123509 (2012) Silicon waveguides and devices for the mid-infrared Appl.
We theoretically investigate several types of plasmonic slot waveguides for enhancing the measured signal in Raman spectroscopy, which is a consequence of electric field and Purcell factor enhancements, as well as an increase in light-matter interaction volume and the Raman signal collection efficiency. An intuitive methodology is presented for calculating the accumulated Raman enhancement factor of an ensemble of molecules in waveguide sensing, which exploits an analytical photon Green function expansion in terms of the waveguide normal modes, and we combine this with a quantum optics formalism of the molecule-waveguide interaction to model Raman scattering. We subsequently show how integrated plasmonic slot waveguides can attain significantly higher Raman enhancement factors: ∼5.3× compared to optofluidic fibers and ∼3.7× compared to planar integrated dielectric waveguides, with a device size and thus analyte volume of at least threeorders of magnitude less. We also provide a comprehensive comparison between the different types of plasmonic slot waveguides based on the important figures-of-merit, and determine the optimal approaches to maximize Raman enhancement. arXiv:1806.06109v1 [physics.optics]
Vanadium dioxide (VO 2 ) is a phase change material (PCM) that exhibits a large change in complex refractive index on the order of unity upon switching from its dielectric to its metallic phase. Although this property is key for the design of ultra-compact optical modulators of only a few-microns in footprint, the high absorption of VO 2 leads to appreciable insertion loss (IL) that limits the modulator performance. In this work, through theory and numerical modeling, we report on a new paradigm, which demonstrates how the use of a hybrid plasmonic waveguide to construct a VO 2 based modulator can improve the performance by minimizing its IL while achieving high extinction ratio (ER) in comparison to a purely dielectric waveguide. The hybrid plasmonic waveguide that contains an additional metal layer with even higher loss than VO 2 enables unique approaches to engineer the electric field (E-field) intensity distribution within the cross-section of the modulator. The resulting Figure-of-Merit FoM = ER/IL is much higher than what is possible by simply incorporating VO 2 into a silicon wire waveguide. A practical modulator design using this new approach, which also includes input and output couplers yields ER = 3.8 dB/µm and IL = 1.4 dB/µm (FoM = 2.7), with a 3-dB optical bandwidth >500 nm, in a device length = 2 µm, and crosssectional dimensions = 200 nm × 450 nm. To our knowledge, this is one of the smallest modulator designs proposed to-date that also exhibits amongst the highest ER, FoM, and optical bandwidth, in comparison to existing designs. In addition to VO 2 , we investigate two other PCMs incorporated within the waveguide structure. The improvements obtained for VO 2 modulators do not extend to other PCMs.
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