On Chip Optical Modulator using Epsilon-Near-Zero Hybrid Plasmonic Platform

Abstract

In this work, we propose a micro-scale modulator architecture with compact size, low insertion loss, high extinction ratio, and low energy/bit while being compatible with the silicon-on-insulator (SOI) platform. This is achieved through the utilization of epsilon-near-zero (ENZ) effect of indium-tin-oxide (ITO) to maximize the attainable change in the effective index of the optical mode. It also exploits the ITO layer in a hybrid plasmonic ring resonator which further intensifies the effect of the changes in both the real and imaginary parts of the effective index. By electrically inducing carriers in the indium tin oxide (ITO), to reach the ENZ state, the resonance condition shifts, and the losses of the hybrid plasmonic ring resonator increases significantly. This mechanism is optimized to maximize the extinction ratio and minimize the insertion loss. The proposed structure is designed to maximize the coupling to and from standard SOI waveguide, used as access ports. In addition, the operational region is reconfigurable by changing the bias voltage.

Electrically Tunable High-Quality Factor Silicon Microring Resonator Gated by High Mobility Conductive Oxide

“…Most reported Si MRRs are driven by reversed PN junctions, which only provide a low E-O tuning efficiency below 40 pm/V. − However, the resonance wavelength of the Si MRR is easily affected by fabrication errors and fluctuations in temperature due to the high thermo-optic (T-O) coefficient of silicon (1.86 × 10 –4 K –1 ), while the reversed PN junction structure cannot sufficiently compensate the drift. Therefore, a thermal heater is widely used to control the resonance wavelength of Si MRR with the sacrifice of high power consumption (in mW/nm) and the requirement of controlling circuits. − Recently, metal-oxide-semiconductor (MOS) Si MRR with heterogeneously integrated materials such as III–V, poly-Si, and transparent conductive oxides (TCOs), have been reported with much higher E-O tuning efficiency. − Of these heterogeneous gate materials, TCOs offer a large plasma dispersion effect and can be easily integrated with silicon photonics by DC- or RF-sputtering. , For example, our group experimentally demonstrated an indium–tin-oxide (ITO)-gated Si MRR, which achieved an ultrahigh E-O tuning efficiency of 271 pm/V using a narrow microring waveguide with a hafnium oxide (HfO 2 ) insulator . However, the quality factor ( Q -factor) is limited to 1000 due to the high optical loss from the ITO gate.…”

Etiology-Discriminative Multimodal Imaging of Left Ventricular Hypertrophy and Synchrotron-Based Assessment of Microstructural Tissue Remodeling

“…X-PCI has proven as a powerful tool for visualizing cardiac microstructure in cardiac biopsies of rat models, human fetal hearts, as well as in endomyocardial biopsies of heart transplantation patients. The modality enables imaging up to the scale of an individual myocyte, demonstrating feasibility of quantification of fiber orientation, vessels and collagen from multiscale 3D datasets; enabling multiresolution, 3D, quantitative ex vivo analysis of cardiac microstructure, without the need for artifact prone slice-processing that strains histological/microscopic reconstruction ( 4 , 5 , 7 , 18 ). In our study, X-PCI and the subsequent analysis - applying machine-learning solutions to provide automated, 3D segmentations of myocardial structure - enabled a novel way to visualize and quantify the complex microstructural abnormalities that inherently influence cardiac mechanics in LVH.…”

“…The tissue was imaged using X-PCI. A multiscale protocol combining a low-resolution (LR) and a high-resolution (HR) setup (5.8 and 0.65 μm pixel size, respectively) was used0 ( 7 ). Briefly, the tissue sample was introduced in a tube with deionized degassed water in order to minimally affect the tissue structural conditions and avoid bubble formation.…”

“…Nevertheless, the relationship between deformation phenotypes and etiology-related microstructural cardiac remodeling has not been reported. While relatively novel in the field of cardiac imaging, synchrotron radiation-based X-ray phase-contrast imaging (X-PCI) can provide high resolution, three-dimensional (3D) histological information on myocardial microstructure ex vivo non-destructively ( 4 – 7 ) – providing a novel approach to visualize complex structural changes related to remodeling in different disease etiologies.…”

Comparison Study of Multi-Slot Designs in Epsilon-Near-Zero Waveguide-Based Electro-Optical Modulators

“…In addition, ITO has a slight change in carrier density and mobility in the on-chip operating temperature range, which support the modulator maintains a stable working performance [21]- [23]. Until now, a variety of ITO-based modulators have been proposed or demonstrated including hybrid modulators [24], [25] and silicon-based modulators [3], [26], [27]. Among the reported ITO-related researches, modulators featuring gigahertz-speed operation [3], ultracompact nanoscale footprint [27], and high modulation depth [28] have been verified experimentally.…”