Numerical Investigation and Design of Electrically-Pumped Self-Pulsing Fano Laser Based on III-V/Silicon Integration

A self-pulsing III-V/silicon laser is designed based on the Fano resonance between a bus-waveguide and a micro-ring resonator, partially covered by the graphene as a nonlinear saturable absorption component. The Fano reflector etched on the straight waveguide is used as one of the cavity mirrors in the coupling region to work with the graphene induced loss and nonlinearity to achieve pulsed lasing in GHz repetition frequency. The detailed lasing characteristics are studied numerically by using the rate equation and finite-difference time-domain (FDTD) simulations. The results show that the CMOS compatible hybrid laser can generate picosecond pulses with repetition rate at 1~3.12 GHz, which increases linearly with the injection current.

Long-range qubit entanglement via rolled-up zero-index waveguide

Preservation of an entangled state in a quantum system is one of the major goals in quantum technological applications. However, entanglement can be quickly lost into dissipation when the effective interaction among the qubits becomes smaller compared to the noise-injection from the environment. Thus, a medium that can sustain the entanglement of distantly spaced qubits is essential for practical implementations. This work introduces the fabrication of a rolled-up zero-index waveguide which can serve as a unique reservoir for the long-range qubit–qubit entanglement. We also present the numerical evaluation of the concurrence (entanglement measure) via Ansys Lumerical FDTD simulations using the parameters determined experimentally. The calculations demonstrate the feasibility and supremacy of the experimental method. We develop and fabricate this novel structure using cost-effective self-rolling techniques. The results of this study redefine the range of light-matter interactions and show the potential of the rolled-up zero-index waveguides for various classical and quantum applications such as quantum communication, quantum information processing, and superradiance.

Microring Zone Structure for Near-Field Probes

Recent advances in Surface Plasmon Resonance (SPR) technologies have shown the possibility of transmission enhancement of localized modes propagating through sub-diffraction wide slits and apertures, resulting in the strong near-field focusing of metallic planar nanostructures. This work presents a new approach to the fabrication of high-resolution near-field optical probes using 3D lithography in combination with numerical finite difference time domain (FDTD) simulations. A narrow 500 nm depth of field focus area was observed both by numerical analysis and near field scanning optical microscopy (NSOM) measurements. Further research and optimization are planned in order to achieve subwavelength focal regions and increased signal intensities.

The importance of Mie resonances in ultra-black dragonfish skin pigment particles

The ultra-black skin of the deep-sea dragonfish consists of small pigment particles which together provide optimal light absorption to prevent detection from bioluminescent predators or prey. The mechanism of light absorption in these pigment particles resembles the nanophotonic approaches to increase solar cell efficiency via Mie scattering and resonances. In this work, the Mie resonance responses of dragonfish pigment particles were investigated with finite-difference time-domain (FDTD) simulations to elucidate the exact mechanism responsible for the ultra-black skin of the dragonfish. Ellipsoidal pigment particles were found to have superior light absorption over spherical pigment particles. The pigment particles were also shown to exhibit forward scattering, demonstrating an important feature for repeated light absorption in pigment-containing skin layers. Although this work contributes to a deeper understanding of the ultra-back skin of the dragonfish, the nanophotonic mechanisms proposed here are likely more general, and could be applied to photovoltaic light management designs and immunometric detection based on light extinction.

10 nm SiO2 TM Slot Mode in Laterally Mismatched Asymmetric Fin-Waveguides

In this paper we demonstrate that by breaking the left/right symmetry in a bi-planar double-silicon on insulator (SOI) photonic crystal (PhC) fin-waveguide, we can couple the conventionally used transverse-electric (TE) polarized mode to the transverse-magnetic (TM) polarization slot-mode. Finite difference time domain (FDTD) simulations indicate that the TE mode couples to the robust TM mode inside the Brillouin zone. Broadband transmission data shows propagation identified with horizontal-slot TM mode within the TE bandgap for fully mismatched fabricated devices. This simultaneously demonstrates TE to TM mode conversion, and the narrowest Si photonics SiO2 slot-mode propagation reported in the literature (10 nm wide slot), which both have many potential telecommunication applications.

Improvement of Shaped Conductive Backfill Material for Grounding Systems

In this paper, some improvements have been proposed for low resistance shaped conductive backfill material (SCBM) based on finite-difference time-domain (FDTD) simulations in grounding systems. It is found SCBM can be produced by conjunction of several layers with conductivity decreasing gradually from inner layer to outer layer, and smooth conductivity reduction between layers would lead to a better grounding performance. It is also found cuboid shape is a much more efficient shape than cube and cylinder shapes for SCBM, and holes can be made on the SCBM’s main body. It suggested to bury SCBM vertically when ground soil permits, otherwise bury SCBM horizontally and deeper burying depth would result in smaller grounding resistance. Results show it is not needed to connect the SCBMs one by one tightly in series SCBM, and some distances is allowed without dramatically increasing grounding resistance.