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.

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 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]

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.

We theoretically investigate the enhancement of surface enhanced Raman spectroscopy (SERS) using hyperbolic stratified nanostructures and compare to metal nanoresonators. The photon Green function of each nanostructure within its environment is first obtained from a semi-analytical modal theory, which is used in a quantum optics formalism of the molecule-nanostructure interaction to model the SERS spectrum. An intuitive methodology is presented for calculating the single molecule enhancement factor (SMEF), which is also able to predict known experimental SERS enhancement factors of an example gold nano-dimer. We elucidate the important figures-of-merit of the enhancement and explore these for different designs. We find that the use of hyperbolic stratified materials can enhance the photonic local density of states (LDOS) by close to 2 times in comparison to pure metal nanostructures, when both designed to work at the same operating wavelengths. However, the increased LDOS is accompanied by higher electric field concentration within the lossy hyperbolic material, which leads to increased quenching that serves to reduce the overall detected SERS enhancement in the far field. For nanoresonators with resonant localized surface plasmon wavelengths in the near-infrared, the SMEF for the hyperbolic stratified nanostructure is approximately an order of magnitude lower than the pure metal counterpart. Conversely, we show that by detecting the Raman signal using a near-field probe, hyperbolic materials can provide an improvement in SERS enhancement compared to using pure metal nanostructures when the probe is sufficiently close (<50 nm) to the Raman active molecule at the plasmonic hotspot.

The expansion of optical network traffic demands the implementation of all-optical signal processing functions such as switching and modulation within the network nodes to scale data speeds and curb power consumption. Toward this end, we experimentally demonstrate ultracompact all-optical modulators based on vanadium dioxide that can be operated by broadband control (800–1000 nm) and signal (1500–1600 nm) wavelengths and are simultaneously switched by pulse energies as low as 6.4 pJ. The devices are integrated on-chip and enable planar propagation of both control and signal light beams. For a 4 μm length modulator, the extinction ratio is 1.68 dB/μm and the insertion loss is 0.98 dB/μm at λ = 1550 nm. To our knowledge, these characteristics together have not been demonstrated previously in a single device. Furthermore, the extinction ratio, switching energy, and switching efficiency have been observed to depend on the modulator length in subtle ways, which is due to the finite distance required for the electromagnetic fields to reach steady-state within the modulator section.

This document provides supplementary information to Broadband, Integrated, Micron-Scale, All-Optical Si 3 N 4 /VO 2 Modulators with pJ Switching Energy, ACS Photonics volume, rst page (year). First, the optical modes of the Si 3 N 4 /VO 2 waveguide modulator and their properties are given. Next, the details of the fabrication process and characterization of the all-optical modulator are provided. The remaining sections of the document elaborates on the measurements and subsequent calculations of 1 modulator insertion loss, switching energy, and the threshold uence for the insulatorto-metal transition in vanadium dioxide, as well as a comparison of our demonstrated device to previous work.Si 3 N 4 /VO 2 Modulator Modes and PropertiesThe wavelength-dependent refractive index n of vanadium dioxide (VO 2 ) is determined from ellipsometry of the deposited polycrystalline lm on a planar substrate; at λ = 1550 nm, the dielectric state refractive index is n d = 2.861 + 0.267i, and the metallic state value is n m = 1.664 + 3.291i. In comparison to previous published values, 1,2 both Re{n d } and Re{n m } from our data are ∼0.3 lower, while Im{n d } is lower but Im{n m } is higher. Although the waveguide is multi-moded at λ = 1550 nm, only the even modes are considered, as a carefully centered Gaussian beam excites only even modes. 3 Details of the modes of the Si 3 N 4 /VO 2 waveguide at the signal wavelength of λ = 1550 nm when VO 2 is in its dielectric state are given in Fig. 1. Here, we choose to utilize the predominantly transverse magnetic (TM) mode, because both a lower IL = 0.20 dB/µm (modal loss when VO 2 is dielectric) and higher ER = 3.04 dB/µm (dierence in modal losses between when VO 2 is metallic and dielectric) are attained compared to the transverse electric (TE) mode. Dierent Si 3 N 4 waveguide dimensions (e.g., w and h) have been scanned in the optimization for the extinction ratio (ER) and insertion loss (IL) in order to come up with the current design. The wavelength