Lumerical Solutions (Canada)

We demonstrate an apodization technique by tapering the corrugations of spiral Bragg grating waveguides on the silicon-on-insulator platform, for the fundamental transverse magnetic mode. The transmission and reflection responses of uniform and apodized spiral Bragg grating waveguides are experimentally compared to show higher sidelobe suppression ratios by the proposed apodization scheme. We also present an apodized, period-chirped spiral Bragg grating waveguide, and the group delay of the proposed device has been measured; the results show an efficient suppression in the ripples of the group delay response.

Recent progress towards realizing quantum emitters (QEs) suitable for integration in quantum information networks stimulates the demand for a self-consistent numerical approach to describe scattering of radiatively limited QEs in complex dielectric environments. As the QE response has to be characterized without the use of phenomenological damping parameters, the divergent nature of the pointlike emitter's in-phase self-field has to be carefully dealt with to avoid unphysical frequency shifts. Here we provide a solution to this problem and show two ways to obtain accurate results in the weak excitation limit using finite-difference time-domain algorithms. One of these approaches lays important groundwork needed for future simulations of nonlinear QE networks. The solution for dealing with the frequency shift reveals that dynamical contributions to the resonant depolarization field of arbitrarily small dielectric objects make crucial contributions to the net dipole moment induced by an external field when radiative scattering is the only source of damping.

Graphene is different from most optical materials in that it is a thin material layer with a thickness as small as one atom. Graphene layers can be incorporated into optical simulations using either a surface conductivity material model or a volumetric permittivity material model; however, introducing graphene through a volumetric permittivity is computationally inefficient because it requires very fine discretization grids. We have recently developed a more efficient approach that enables the use of comparatively coarse grids by formulating a discretization of Maxwell’s equations (in the time or frequency domains) that combines a surface conductivity description of graphene layers with a volumetric permittivity description of other optical materials. This approach includes the full dispersion characteristics of graphene as specified by the Kubo formula. This paper demonstrates how the combined material description approach can be used to efficiently model state-of-the-art devices that take advantage of the energy confinement provided by surface plasmons. We show how to efficiently model TE and TM polarized surface plasmons, a surface plasmon waveguide switch, and an electro-optical modulator. This last example also includes electrical simulations of graphene and demonstrates how both optical and electrical simulations can be combined to produce a complete model of a graphene based device. For each example, we compare with previously published results, including experimental results.

Fiber-chip edge couplers are extensively used in integrated optics for coupling of light between planar waveguide circuits and optical fibers. In this work, we report on a new fiber-chip edge coupler concept with large mode size for silicon photonic wire waveguides. The coupler allows direct coupling with conventional cleaved optical fibers with large mode size while circumventing the need for lensed fibers. The coupler is designed for 220 nm silicon-on-insulator (SOI) platform. It exhibits an overall coupling efficiency exceeding 90%, as independently confirmed by 3D Finite-Difference Time-Domain (FDTD) and fully vectorial 3D Eigenmode Expansion (EME) calculations. We present two specific coupler designs, namely for a high numerical aperture single mode optical fiber with 6 µm mode field diameter (MFD) and a standard SMF-28 fiber with 10.4 µm MFD. An important advantage of our coupler concept is the ability to expand the mode at the chip edge without leading to high substrate leakage losses through buried oxide (BOX), which in our design is set to 3 µm. This remarkable feature is achieved by implementing in the SiO2 upper cladding thin high-index Si3N4 layers. The Si3N4 layers increase the effective refractive index of the upper cladding near the facet. The index is controlled along the taper by subwavelength refractive index engineering to facilitate adiabatic mode transformation to the silicon wire waveguide while the Si-wire waveguide is inversely tapered along the coupler. The mode overlap optimization at the chip facet is carried out with a full vectorial mode solver. The mode transformation along the coupler is studied using 3D-FDTD simulations and with fully-vectorial 3D-EME calculations. The couplers are optimized for operating with transverse electric (TE) polarization and the operating wavelength is centered at 1.55 µm.

Silicon photonics is nothing new. It has been around for decades, but in recent years, it has gained traction as electronic design challenges increase drastically with their atomic-level limitations. Silicon photonics has made significant advancements during this period, but there are many obstacles without an acceptable level of comfort as seen by the lack of semiconductor community involvement. Apart from a series of technological barriers, such as extreme fabrication sensitivity, inefficient light generation on-chip, etc., there are also certain design challenges. In this chapter, we will discuss the challenges and the opportunities in photonic integrated circuit design software tools, examine existing design flows for photonics design and how these fit different design styles, and review the activities in collaboration and standardization efforts to improve design flows.

We present a novel design methodology for silicon photonic integrated circuits (PIC) that integrates Cadence's Spectre with Lumerical's INTERCONNECT. It supports parametric analysis of bidirectional, multi-mode PICs, with electrical feedback.

We present a vision for photonic circuit simulation within sophisticated EDA-style design flows and the tool development roadmap to achieve it. Our approach aims to deliver highly-usable, predictive capabilities for a variety of use cases, that seamlessly interoperates with 3rd-party, best-in-class design tools.

We will demonstrate the simulation of photonic integrated circuits, initially using analytical models for each element of the circuit. The results of physical electromagnetic and electrical solvers will then be incorporated to simulate physically realistic photonic integrated circuits. The methodology presented is amenable for use in emerging optical circuit simulation standards.

ABSTRACT We apply a previously developed 3D Finite-Difference Time-Domain (FDTD) simulation method to model the optical phase contrast microscopic (OPCM) visualization of Gold nanoparticles (NPs) attached to the nucleus of a singe biological cell. We consider a realistic size 3D cell model at optical immersion conditions, i.e. when the refractive index values of the cytoplasm and of the extra-cellular medium are eq ual. The visual effect of the Gold NPs is studied at both resonant and non-resonant conditions. The results show that, at resonance, there are specific visual patterns that could be used for the identification of the presence of NPs at the nu cleus’ surface. The model demons trates the capability to model the specific conditions of OPCM image enhancement by optically controlling the resonant properties of the NPs. Keywords: Biological cell, finite-difference time-domain method, optical phase contrast microscope, optical clearing effect, Gold NPs 1. INTRODUCTION The application of optical software simulation and modeling tools in biomedical optics is a growing area. Biomedical optics researchers need optical simulation tools to acquire a deeper understanding of the light-cell-tissue interaction processes.

The FDTD modeling technique is applied to provide additional insight on the effect of the cell membrane thickness in optical immersion enhanced phase contrast microscope imaging. Pilot results on the application of the FDTD approach for studying the implementation of the optical immersion technique for the visualization of single and multiple gold nanoparticles in biological cells are also presented. The paper focuses on three different scenarios considering single biological cells containing i) cytoplasm and membrane, ii) cytoplasm, nucleus and membrane, and iii) cytoplasm, nucleus, gold nanoparticle(s) and membrane. To the best knowledge of authors, this is the first research study discussing the cell membrane thickness and single gold nanoparticle effects on the forward scattered light from biological cells. The potential of the FDTD approach and its applicability to new and promising biomedical optics research areas such as the study of optical immersion technique enhanced bio-imaging is demonstrated.