Sex differences in metabolic adaptation in infants with cyanotic congenital heart disease.

BACKGROUND: Female infants with congenital heart disease (CHD) face significantly higher postoperative mortality rates after adjusting for cardiac complexity. Sex differences in metabolic adaptation to cardiac stressors may be an early contributor to cardiac dysfunction. In adult diseases, hypoxic/ischemic cardiomyocytes undergo a cardioprotective metabolic shift from oxidative phosphorylation to glycolysis which appears to be regulated in a sexually dimorphic manner. We hypothesize sex differences in cardiac metabolism are present in cyanotic CHD and detectable as early as the infant period. METHODS: RNA sequencing was performed on blood samples (cyanotic CHD cases, n = 11; controls, n = 11) and analyzed using gene set enrichment analysis (GSEA). Global plasma metabolite profiling (UPLC-MS/MS) was performed using a larger representative cohort (cyanotic CHD, n = 27; non-cyanotic CHD, n = 11; unaffected controls, n = 12). RESULTS: Hallmark gene sets in glycolysis, fatty acid metabolism, and oxidative phosphorylation were significantly enriched in cyanotic CHD females compared to male counterparts, which was consistent with metabolomic differences between sexes. Minimal sex differences in metabolic pathways were observed in normoxic patients (both controls and non-cyanotic CHD cases). CONCLUSION: These observations suggest underlying differences in metabolic adaptation to chronic hypoxia between males and females with cyanotic CHD. IMPACT: Children with cyanotic CHD exhibit sex differences in utilization of glycolysis vs. fatty acid oxidation pathways to meet the high-energy demands of the heart in the neonatal period. Transcriptomic and metabolomic results suggest that under hypoxic conditions, males and females undergo metabolic shifts that are sexually dimorphic. These sex differences were not observed in neonates in normoxic conditions (i.e., non-cyanotic CHD and unaffected controls). The involved metabolic pathways are similar to those observed in advanced heart failure, suggesting metabolic adaptations beginning in the neonatal period may contribute to sex differences in infant survival.

Demonstration Project of Long-Acting Antiretroviral Therapy in a Diverse Population of People With HIV.

BACKGROUND: Intramuscular cabotegravir (CAB) and rilpivirine (RPV) is the only long-acting antiretroviral therapy (LA-ART) regimen approved for people with HIV (PWH). Long-acting ART holds promise for improving outcomes among populations with barriers to adherence but is only approved for PWH who have virologic suppression with use of oral ART before initiating injectables. OBJECTIVE: To examine LA-ART in a population of PWH that includes those with viremia. DESIGN: Observational cohort study. SETTING: Urban academic safety-net HIV clinic. PATIENTS: Publicly insured adults living with HIV with and without viral suppression, high rates of unstable housing, mental illness, and substance use. INTERVENTION: Demonstration project of long-acting injectable CAB-RPV. MEASUREMENTS: Descriptive statistics summarizing cohort outcomes to date, based on pharmacy team logs and electronic medical record data. RESULTS: Between June 2021 and November 2022, 133 PWH at the Ward 86 HIV Clinic were started on LA-ART, 76 of whom had virologic suppression while using oral ART and 57 of whom had viremia. The median age was 46 years (IQR, 25 to 68 years); 117 (88%) were cisgender men, 83 (62%) had non-White race, 56 (42%) were experiencing unstable housing or homelessness, and 45 (34%) had substance use. Among those with virologic suppression, 100% (95% CI, 94% to 100%) maintained suppression. Among PWH with viremia, at a median of 33 days, 54 of 57 had viral suppression, 1 showed the expected 2-log10 reduction in HIV RNA level, and 2 experienced early virologic failure. Overall, 97.5% (CI, 89.1% to 99.8%) were projected to achieve virologic suppression by a median of 33 weeks. The current virologic failure rate of 1.5% in the cohort is similar to that across registrational clinical trials at 48 weeks. LIMITATION: Single-site study. CONCLUSION: This project demonstrates the ability of LA-ART to achieve virologic suppression among PWH, including those with viremia and challenges to adherence. Further data on the ability of LA-ART to achieve viral suppression in people with barriers to adherence are needed. PRIMARY FUNDING SOURCE: National Institutes of Health, City and County of San Francisco, and Health Resources and Services Administration.

Clinical outcomes in critically ill children on extracorporeal membrane oxygenation with severe thrombocytopenia.

INTRODUCTION: As international guidelines suggest keeping the platelet count between 50 and 100 × 109 cells/L in children on extracorporeal membrane oxygenation (ECMO), platelet transfusions are administered to two-thirds of ECMO days, and up to 70% of these patients still bleed. We aim to describe outcomes in critically ill children who develop severe thrombocytopenia on ECMO. METHODS: Single-center retrospective study, enrolling critically ill children on ECMO admitted at Children's Memorial Hermann, TX, between 1/2018 and 12/2022, with at least one platelet count below 50 × 109 cells/L (severe thrombocytopenia). Platelet counts were measured four times a day. We report platelet transfusion, bleeding, hemolysis, and clotting events within 6 h after transfusion, as well as ECMO duration and mortality. RESULTS: We enrolled 54 patients representing 337 ECMO days and 1190 platelet counts. Median weight was 3.7 kg and 54% were male. Severe thrombocytopenia was observed in 56% of platelet counts. Severe thrombocytopenia was not associated with bleeding in the subsequent 6 h (18% vs 20%, p = .95), but was associated with more frequent platelet transfusions (18% vs 11%, p = .001). There was no correlation between time spent with severe thrombocytopenia and the duration of ECMO (R2 = 0.03). While the time spent with severe thrombocytopenia was not associated with on-ECMO mortality rate (p = .36), there was an association with in-hospital mortality rate (p = .003). CONCLUSIONS: Our results indicate a restrictive platelet transfusion strategy is not associated with higher proportions of subsequent bleeding, duration of ECMO, or on-ECMO mortality rate. Multicenter studies are needed to evaluate further the appropriateness of this strategy.

The Brief Human Immunodeficiency Virus (HIV) Index: A Rapid 3-Item Scale to Measure Engagement in HIV Care.

We created a brief version of The Index, a validated patient-reported measure that has potential to quickly identify patients at risk for poor retention. We analyzed Index scores from 2406 patients from 2016 to 2017 in a national cohort of patients in human immunodeficiency virus (HIV) care. Index scores predicted poor retention 12 months after administered.

A factorial experiment grounded in the multiphase optimization strategy to promote viral suppression among people who inject drugs on the Texas-Mexico border: a study protocol.

BACKGROUND: People who inject drugs living with HIV (PWIDLH) suffer the lowest rates of HIV viral suppression due to episodic injection drug use and poor mental health coupled with poor retention in HIV care. Approximately 44% of PWIDLH along the US-Mexico border are retained in care and only 24% are virally suppressed. This underserved region faces a potential explosion of transmission of HIV due to highly prevalent injection drug use. This protocol describes an optimization trial to promote sustained viral suppression among Spanish-speaking Latinx PWIDLH. METHODS: The multiphase optimization strategy (MOST) is an engineering-inspired framework for designing and building optimized interventions and guides this intervention. The primary aim is to conduct a 24 factorial experiment in which participants are randomized to one of 16 intervention conditions, with each condition comprising a different combination of four behavioral intervention components. The components are peer support for methadone uptake and persistence; behavioral activation therapy for depression; Life-Steps medication adherence counseling; and patient navigation for HIV care. Participants will complete a baseline survey, undergo intervention, and then return for 3-,6-,9-, and 12-month follow-up assessments. The primary outcome is sustained viral suppression, defined as viral loads of < 40 copies per mL at 6-,9-, and 12-month follow-up assessments. Results will yield effect sizes for each component and each additive and interactive combination of components. The research team and partners will make decisions about what constitutes the optimized multi-component intervention by judging the observed effect sizes, interactions, and statistical significance against real-world implementation constraints. The secondary aims are to test mediators and moderators of the component-to-outcome relationship at the 6-month follow-up assessment. DISCUSSION: We are testing well-studied and available intervention components to support PWIDLH to reduce drug use and improve their mental health and engagement in HIV care. The intervention design will allow for a better understanding of how these components work in combination and can be optimized for the setting. TRIAL REGISTRATION: This project was registered at clinicaltrials.gov (NCT05377463) on May 17th, 2022.

Social and environmental determinants influencing injection drug use and HIV risk among two sister cities on the US-Mexico border: a comparative cross-sectional study, 2016-2018.

The economic, social, cultural and political milieus that influence injection drug-related HIV risk behaviors along the US-Mexico border in the previous decade have been studied comparing cities on an East-West axis. In an effort to inform interventions targeting factors beyond the individual level, we used a cross-sectional study design comparing people who inject drugs during 2016-2018, living on a North-South axis, in two cities-Ciudad Juárez, Chihuahua, Mexico and El Paso, Texas, USA-situated at the midpoint of the 2000 US-Mexico borderland stretch. We conceptualize injection drug use and its antecedents and consequences as influenced by factors operating at various levels of influence. Results of analysis comparing samples recruited from each border city indicated significant differences in demographic, socioeconomic, micro- and macro-level factors that affect risk. Similarities emerged in individual-level risk behaviors and some dynamics of risk at the drug use site most frequented to use drugs. In addition, analyses testing associations across samples indicated that different contextual factors such as characteristics of the drug use sites influenced syringe sharing. In this article, we reflect on the potential tailored interventions needed to target the context of HIV transmission risk among people who use drugs and reside in binational environment.

A versatile platform for generating engineered extracellular vesicles with defined therapeutic properties.

Extracellular vesicles (EVs) are an important intercellular communication system facilitating the transfer of macromolecules between cells. Delivery of exogenous cargo tethered to the EV surface or packaged inside the lumen are key strategies for generating therapeutic EVs. We identified two "scaffold" proteins, PTGFRN and BASP1, that are preferentially sorted into EVs and enable high-density surface display and luminal loading of a wide range of molecules, including cytokines, antibody fragments, RNA binding proteins, vaccine antigens, Cas9, and members of the TNF superfamily. Molecules were loaded into EVs at high density and exhibited potent in vitro activity when fused to full-length or truncated forms of PTGFRN or BASP1. Furthermore, these engineered EVs retained pharmacodynamic activity in a variety of animal models. This engineering platform provides a simple approach to functionalize EVs with topologically diverse macromolecules and represents a significant advance toward unlocking the therapeutic potential of EVs.

Pre- and post-operative cardiovascular CT in Stage I single ventricle palliation.

OBJECTIVES: The aim of this study is to describe clinical utility of low dose cardiac computed tomography (CT) in the evaluation of single ventricle physiology before and after Stage I palliation. BACKGROUND: Despite the increased utilization of CT imaging and advancement of CT technology, there are limited studies describing the routine clinical use of cardiac CT and radiation dose parameters in the single ventricle Stage I palliation. METHODS: This single center, retrospective study included 57 infants with single ventricle physiology who underwent cardiac CT scans between January 1, 2016 and November 30, 2020. Patients' demographic information, diagnosis, indication, total dose length product (DLP), computed tomographic dose index volume (CTDIvol), cardiac CT findings and intraoperative or intraprocedural findings were reviewed. Estimated effective radiation dose was calculated using a previously published conversion rate. RESULTS: The studies were performed using different generations of CT scanners over the 4 years period: Somatom AS 128, Somatom definition edge, Somatom Force (Siemens Medical Solutions). The studies performed with dual source scanner with prospective gated technique have lower radiation dose exposure with median effective radiation dose of 0.32 mSv. CONCLUSION: Pre- and post-operative cardiovascular CT in Stage I single ventricle palliation using newer generation scanners with prospective gated technique can be done with minimal radiation exposure and good image quality. Cardiac CT is a powerful imaging modality for better management planning in this group of patients.

Modern advances regarding interatrial communication in congenital heart defects.

BACKGROUND: The interatrial communication, one of the most frequent congenital heart defects, represents an important intracardiac shunt between systemic and pulmonary circulations. Direction and magnitude of the interatrial shunting depends upon several features, including defect size, shape and location, pressure difference between right and left atrium, and difference in right and left ventricular compliance. METHODS: In this review article, the presence or absence of interatrial communication, and its role, have been analyzed, as they can have a critical impact on the cardiovascular physiopathology, and the interatrial communication can prove to be either clinically harmful, useful or indispensable. Accordingly, the utility and role of the interatrial communication in modern congenital, pediatric and adult, disease has evolved, with modification of the indications to close, maintain patency, or create an interatrial communication. RESULTS: The interatrial communication and shunting can be manipulated to maximize the oxygen delivery to the tissues, accordingly with the underlying congenital heart defect. While not always relevant to patients with bi-ventricular circulations, this becomes extremely important in children and adults with complex congenital heart defects. CONCLUSIONS: With improving long-term survival for the vast majority of congenital heart patients, an advanced understanding of the role and utility of the interatrial communication, and of all the possibilities of its manipulation, is essential to improve the patient outcomes.

Absorbable sutures for cardiopulmonary bypass purse strings in pediatric heart surgery.

BACKGROUND: Absorbable sutures, commonly used in general surgery, are not routinely used as purse strings for arterial and venous cannulation for cardiopulmonary bypass in pediatric heart surgery. The general concern is absorbable sutures could predispose to immediate postoperative bleeding; this safety concern has been evaluated in this retrospective study. MATERIALS AND METHODS: A single center, retrospective study, was conducted with criteria for inclusion patient <18 years of age, operation on with cardiopulmonary bypass for heart surgery from July 1, 2018 to June 30, 2020, with purse strings for cannulation performed with absorbable sutures. Data collection included demographics at the time of surgery, site of arterial and venous cannulation with absorbable purse strings, bleeding, required reoperation, related hospital mortality, and complications. RESULTS: One hundred and ninety-eight patients, mean ± standard deviation (SD) age of 1597 ± 3021 days, mean ± SD body weight of 15.9 ± 18.8 kg, were operated on using absorbable sutures for purse strings for arterial and venous cannulation: No bleeding was reported, either intraoperative or in the immediate postoperative period, related to the type of sutures used for purse strings for cannulation. No hospital deaths or complications related to the type of sutures were observed. CONCLUSIONS: Based on the results of our analysis, we can conclude that the utilization of purse strings absorbable sutures for arterial and venous cannulation for cardio-pulmonary bypass in children is safe in relationship to the intraoperative and immediate postoperative period. No complications related to the use of absorbable sutures have been observed in a large pediatric patient population.

Ebstein's Anomaly: From Fetus to Adult-Literature Review and Pathway for Patient Care.

Ebstein's anomaly, first described in 1866 by Dr William Ebstein, accounts for 0.3-0.5% of congenital heart defects and represents 40% of congenital tricuspid valve abnormalities. Ebstein's anomaly affects the development of the tricuspid valve with widely varying morphology and, therefore, clinical presentation. Associated congenital cardiac lesions tend to be found more often in younger patients and may even be the reason for presentation. Presentation can vary from the most extreme form in fetal life, to asymptomatic diagnosis late in adult life. The most symptomatic patients need intensive care support in the neonatal period. This article summarizes and analyzes the literature on Ebstein's anomaly and provides a framework for the investigation, management, and follow-up of these patients, whether they present via fetal detection or late in adult life. For each age group, the clinical presentation, required diagnostic investigations, natural history, and management are described. The surgical options available for patients with Ebstein's anomaly are detailed and analyzed, starting from the initial mono-leaflet repairs to the most recent cone repair and its modifications. The review also assesses the effects of pregnancy on the Ebstein's circulation, and vice versa, the effects of Ebstein's on pregnancy outcomes. Finally, two attached appendices are provided for a structured echocardiogram protocol and key information useful for comprehensive Multi-Disciplinary Team discussion.

Essential role of cardiac computed tomography for surgical decision making in children with total anomalous pulmonary venous connection and single ventricle.

BACKGROUND: Total anomalous pulmonary venous connection (TAPVC) is a major risk factor in infants with single ventricle (SV). Exact definition of TAPVC anatomy is crucial for surgical planning. AIM: To evaluate the role of cardiac computed tomography (CT) in this setting. METHODS: Retrospective review of 13 infants who underwent TAPVC repair associated with SV from May 2016 to October 2021. Anatomy, incidence, and mechanisms of pulmonary venous obstruction (PVO) were described. Cardiac CT diagnostic yield was compared to echocardiography (echo). RESULTS: Of 13 infants, median age and weight were 24 days (range 2-303 days) and 3.2 (range 2.6-9.1) kg, 8 (62%) were male, 4 (31%) premature, and 11 (85%) had heterotaxy syndrome. All infants had pre- and postoperative echo; 13 had preoperative and 8 (62%) had postoperative cardiac CT. Type of TAPVC: six (46%) supracardiac, two (15%) intracardiac, one (8%) infracardiac, and four (31%) mixed, with pulmonary veins draining in >1 confluence in nine (69%). PVO was present in 6/13 (46%) preoperatively and 5/13 (31%) postoperatively. Mechanisms of PVO: 9/11 (82%) stenosis, 1/9 (9%) membrane formation, and 1/9 (9%) external compression. The sensitivity to diagnose PVO was 45.5% for echo and 100% for cardiac CT, the specificity was 100% for both. No discrepancy was found between cardiac CT and intraoperative findings, but echo had a complete preoperative diagnosis in 1/13 (8%) (p < .00001, Fisher exact test). CONCLUSIONS: Cardiac CT is essential to evaluate pre- and postoperative TAPVC in SV for surgical decision making and long term follow up.

The Secrets of the Frogs Heart.

The heart of the African clawed frog has a double-inlet and single-outlet ventricle supporting systemic and pulmonary circulations via a truncus, and a lifespan of 25-30 years. We sought to understand the unique cardiac anatomic and physiologic characteristics, with balanced circulation and low metabolic rate, by comparing the basic anatomy structures with focused echocardiography and cardiac magnetic resonance imaging. Twenty-four adult female African clawed frogs were randomly subjected to anatomic dissection (n = 4), echocardiography (n = 10), and cardiac magnetic resonance (n = 10). All anatomical features were confirmed and compared with echocardiography and cardiac magnetic resonance imaging. The main characteristics of the cardiovascular circulation in frogs are the following: Intact interatrial septum, with two separate atrio-ventricular valves, preventing atrial mixing of oxygenated and desaturated blood. Single spongiform ventricular cavity, non-conducive for homogeneous mixing. Single outlet with a valve-like mobile spiral structure, actively streaming into systemic and pulmonary arteries. Intact interatrial septum, spongiform ventricle, and valve-like spiral in the conus arteriosus are likely responsible for balanced systemic and pulmonary circulation in frogs, in spite of double-inlet and single-outlet ventricle.

Total anomalous pulmonary venous connection: 16 years of surgical results in a single center.

PURPOSE: The aim of the study was to analyze the surgical outcome of patients with total anomalous pulmonary venous connection (TAPVC) who underwent cardiac surgery. METHODS: A retrospective study was carried out. Patients with diagnosis of TAPVC undergoing cardiac surgery at the National Institute of Cardiology Ignacio Chávez, from January 1, 2003 and June 30, 2019 were included. Descriptive statistics were calculated, as well as a bivariate analysis of the variables associated with mortality. A logistic regression model was included to determine risk factors associated with the main outcome and survival was analyzed using the Kaplan-Meier method. RESULTS: A total of 5314 patients diagnosed with congenital heart disease (CHD) underwent surgery, 414 (7.8%) were patients with TAPVC, with an average age of 17.1 ± 34.6 months, 58.2% were male. It was frequent in infants (61.6%) and preschool (19.6%). Predominant type was supracardiac TAPVC (47.4%). Pulmonary venous obstruction (PVO) occurred in 32.1%. Risk factors associated with mortality were infracardiac TAPVC (odds ratio [OR]: 3.26; 95% confidence interval [CI]: 1.17-9.03; p = .02), PVO (OR: 2.56; 95% CI: 1.05-6.22; p = .03) and postoperative mechanical ventilation (OR: 1.005; 95% CI: 1.002-1.008; p = .01). Overall survival was 87.2%, with better outcomes in adolescents (100%), children (94.1%), mixed TAPVC (96%), and cardiac TAPVC (91.9%; p < .001). CONCLUSIONS: The survival of our institution after surgical correction of TAPVC is similar to that of other referral centers, where patients with infracardiac TAPVC and newborns worse outcomes. All patients must undergo a rigorous evaluation to determine an adequate repair strategy.

Surgical outcomes among children with bicuspid aortic valve: 17 years of experience in a single center. First report in Mexico.

PURPOSE: To evaluate the clinical and surgical outcomes among children with bicuspid aortic valve who underwent cardiac surgery. METHODS: This observational and retrospective study included patients with a diagnosis of bicuspid aortic valve who underwent cardiac surgery between January 1, 2003, and March 31, 2020. Demographic characteristics and perioperative conditions were described. RESULTS: One hundred and sixteen patients were included, with a mean age of 12.4 ± 4.2 years; 63.2% were male. The most frequent diagnosis was congenital aortic stenosis (23.5%), followed by connective tissue disorders (16%). Mechanical aortic prostheses were used in 87.7% of cases, with a mean size of 21 ± 2.6 mm. The main factors associated with mortality were valve prosthesis dysfunction (odds ratio [OR]: 12.44; 95% confidence interval [CI]: 1.05-147.48; p = .04) and reoperation (OR: 24.29; 95% CI: 1.03-570.08; p = .04). The overall survival was 87.9%, with better outcomes among those who did not undergo reoperation (Log Rank, p = .01). CONCLUSIONS: Outcomes after aortic valve replacement in children with bicuspid aortic valve are excellent in the short and long term, regardless of using mechanical or biological prostheses.

Design of Plasmonic Yagi-Uda Nanoantennas for Chip-Scale Optical Wireless Communications.

Optical wireless transmission has recently become a major cutting-edge alternative for on-chip/inter-chip communications with higher transmission speeds and improved power efficiency. Plasmonic nanoantennas, the building blocks of this new nanoscale communication paradigm, require precise design to have directional radiation and improved communication ranges. Particular interest has been paid to plasmonic Yagi-Uda, i.e., the optical analog of the conventional Radio Frequency (RF) Yagi-Uda design, which may allow directional radiation of plasmonic fields. However, in contrast to the RF model, an overall design strategy for the directional and optimized front-to-back ratio of the radiated far-field patterns is lacking. In this work, a guide for the optimized design of Yagi-Uda plasmonic nanoantennas is shown. In particular, five different design conditions are used to study the effects of sizes and spacing between the constituent parts (made of Au). Importantly, it is numerically demonstrated (using the scattered fields) that closely spaced nanoantenna elements are not appropriated for directional light-to-plasmon conversion/radiation. In contrast, if the elements of the nanoantenna are widely spaced, the structure behaves like a one-dimensional array of nanodipoles, producing a funnel-like radiation pattern (not suitable for on-chip wireless optical transmission). Therefore, based on the results here, it can be concluded that the constituent metallic rib lengths must be optimized to exhibit the resonance at the working wavelength, whilst their separations should follow the relation λeff/π, where λeff indicates the effective wavelength scaling for plasmonic nanostructures.

Optimization of Magnetoplasmonic ε-Near-Zero Nanostructures Using a Genetic Algorithm.

Magnetoplasmonic permittivity-near-zero (ε-near-zero) nanostructures hold promise for novel highly integrated (bio)sensing devices. These platforms merge the high-resolution sensing from the magnetoplasmonic approach with the ε-near-zero-based light-to-plasmon coupling (instead of conventional gratings or bulky prism couplers), providing a way for sensing devices with higher miniaturization levels. However, the applications are mostly hindered by tedious and time-consuming numerical analyses, due to the lack of an analytical relation for the phase-matching condition. There is, therefore, a need to develop mechanisms that enable the exploitation of magnetoplasmonic ε-near-zero nanostructures' capabilities. In this work, we developed a genetic algorithm (GA) for the rapid design (in a few minutes) of magnetoplasmonic nanostructures with optimized TMOKE (transverse magneto-optical Kerr effect) signals and magnetoplasmonic sensing. Importantly, to illustrate the power and simplicity of our approach, we designed a magnetoplasmonic ε-near-zero sensing platform with a sensitivity higher than 56∘/RIU and a figure of merit in the order of 102. These last results, higher than any previous magnetoplasmonic ε-near-zero sensing approach, were obtained by the GA intelligent program in times ranging from 2 to 5 min (using a simple inexpensive dual-core CPU computer).

Magnetically Tunable Micro-Ring Resonators for Massive Magneto-Optical Modulation in Dense Wavelength Division Multiplexing Systems.

We demonstrate, numerically, a new concept for on-chip magneto-optical (MO) modulation in dense wavelength division multiplexing (DWDM) applications. Our idea uses materials and mechanisms that are compatible with current silicon-on-insulator fabrication and CMOS technologies for monolithic integration. The physics behind our idea stems in the exploitation of the enhanced MO activity of a micro-ring, made of cerium substituted yttrium iron garnet (Ce:YIG) material, to actively manipulate the resonance wavelengths of an adjacent micro-ring resonator (MRR) of silicon (Si). This active manipulation of the latter MO-MRR structure is used to modulate the optical signal traveling through a side-coupled Si bus waveguide. Moreover, by proper tailoring multiple MO-MRRs (side-coupled to the single Si bus waveguide) to match wavelength channels in DWDM across the entire C-band optical communications spectrum, we extend our proposal to massive and dynamic MO modulation in DWDM applications. Significantly, we noticed that the active MO shifting of the resonant wavelength (used for MO modulation here) can be used for improvements in the spectrum utilization efficiency in future elastic optical networks (EONs).

Bulk Plasmon Polariton Modes in Hyperbolic Metamaterials for Giant Enhancement of the Transverse Magneto-Optical Kerr Effect.

We demonstrate a concept for the giant enhancement of the transverse magneto-optical Kerr effect (TMOKE) using bulk plasmon polariton (BPP) modes in non-magnetic multilayer hyperbolic metamaterials (HMMs). Since the BPP modes are excited through the attenuated total reflection (ATR) mechanism, using a Si-based prism-coupler, we considered a single dielectric magneto-optical (MO) spacer between the prism and the HMM. The working wavelength was estimated, using the effective medium approach for a semi-infinite dielectric-plasmonic multilayer, considering the region where the system exhibits type II HMM dispersion relations. Analytical results, by means of the scattering matrix method (SMM), were used to explain the physical principle behind our concept. Numerical results for giant TMOKE values (close to their maximum theoretical values, ±1) were obtained using the finite element method (FEM), applying the commercial software COMSOL Multiphysics. Our proposal comprises a simple and experimentally feasible structure that enables the study of MO phenomena in HMMs, which may find application in future nanostructured magnetoplasmonic metamaterials for active nanophotonic devices.