Development and validation of a prediction model for frailty in breast cancer patients with extended survival.

BACKGROUND: Breast cancer (BC) patients with extended survival show a higher incidence of frailty. This study aimed to develop and validate a novel model combining sociodemographic factors (SF) and disease-related factors (DRF) to identify frailty in BC patients with extended survival. METHODS: This cross-sectional study examined data from 1167 patients admitted to a large urban academic medical centre. Three types of predictive models were constructed in the training set (817 patients): the SF model, the DRF model, and the SF + DRF model (combined model). The model performance and effectiveness were assessed using receiver operating characteristic (ROC) curves, calibration plots and decision curves analysis (DCA). Then the model was subsequently validated on the validation set. RESULTS: The incidence of frailty in BC patients with extended survival was 35.8%. We identified six independent risk factors including age, health status, chemotherapy, endocrine therapy, number of comorbidities and oral medications. Ultimately, we constructed an optimal model (combined model C) for frailty. The predictive model showed significantly high discriminative accuracy in the training set AUC: 0.754, (95% CI, 0.719-0.789; sensitivity: 76.8%, specificity: 62.2%) and validation set AUC: 0.805, (95% CI, 0.76-0.85), sensitivity: 60.8%, specificity: 87.1%) respectively. A prediction nomogram was constructed for the training and validation sets. Calibration and DCA were performed, which indicated that the clinical model presented satisfactory calibration and clinical utility. Ultimately, we implemented the prediction model into a mobile-friendly web application that provides an accurate and individualized prediction for BC. CONCLUSIONS: The present study demonstrated that the prevalence of frailty in BC patients with extended survival was 35.8%. We developed a novel model for screening frailty, which may provide evidence for frailty screening and prevention.

Effect of transglutaminase on ovalbumin emulsion gels as carriers of encapsulated probiotic bacteria.

BACKGROUND: The use of emulsion gels to protect and deliver probiotics has become an important topic in the food industry. This study used transglutaminase (TGase) to regulate ovalbumin (OVA) to prepare a novel emulsion gel. The effects of OVA concentration and the addition of TGase on the microstructure, rheological properties, water-holding capacity, and stability of the emulsion gels were investigated. RESULTS: With the addition of TGase and the increasing OVA, the particle size of the emulsion gels decreased significantly (P < 0.05). The gels with TGase exhibited greater water holding, hardness, and chewiness to some extent by forming a more uniform and stable system. After simulated digestion, the survival rate of Bifidobacterium lactis embedded in OVA emulsion gels improved significantly in comparison with the oil-water mixture as a result of the protective effect of the emulsion gel encapsulation. CONCLUSION: By increasing the OVA content and adding TGase, the rheological characteristics, stability, and encapsulation capability of the OVA emulsion gel could be enhanced, providing a theoretical basis for the use of emulsion gels to construct probiotic delivery systems. © 2023 Society of Chemical Industry.

Study on the Differences of Icon Cognition of Graphical Interface for Age-Friendly Design.

Icon cognitive impairment is one of the main difficulties for older users to use smart products. This study explores the impact of icon style, icon concreteness and both together on understanding icons by comparing the cognitive differences between two groups of users, young and old. The performance of different types of icons on cognitive performance was analyzed specifically through a comprehensive cognitive load assessment method of behavioral, physiological and subjective data. The results showed that the cognitive performance of skeuomorphism concrete icons was higher and the cognitive load was lower when the user group was novice or older users with less experience in interacting with the GUI; the cognitive performance of flat concrete icons was higher and the cognitive load was lower when the user group was familiar or young users with more experience in interacting with the GUI. From the perspective of cognitive differences between young and old, the results of this study provide a reference for future icon design of interactive interfaces for older people smart terminals to help designers and developers achieve a better user experience for the aging group, which has practical significance for the age-friendly design of graphical interfaces.

Athermal echelle grating and tunable echelle grating demultiplexers using a Mach-Zehnder interferometer launch structure.

We present a comparative experimental study of three silicon photonic echelle grating demultiplexers that are integrated with a Mach-Zehnder interferometer (MZI) launch structure. By appropriate choice of the MZI configuration, the temperature induced shift of the demultiplexer channel wavelengths can be suppressed (athermal) or enhanced (super-thermal) or be controlled by an on-chip micro-heater. The latter two configurations allow the channel wavelengths to be actively tuned using lower power than possible by temperature tuning a conventional echelle demultiplexer. In the athermal configuration, the measured channel spectral shift is reduced to less than 10 pm/°C, compared to the 83 pm/°C shift for an unmodified echelle device. In super-thermal operation an enhanced channel temperature tuning rate of 170 pm/°C is achieved. Finally, by modulating the MZI phase with an on-chip heater, the demultiplexer channels can be actively tuned to correct for ambient temperature fluctuations up to 20 °C, using a drive current of less than 20 mA.

Benefits of Dietary Management in Breast Cancer Patients: A Systematic Review and Meta-Analysis.

The World Cancer Research Fund/American Institute of Cancer Research recommendations include guidance on diet, nutrition, and weight management for people with cancer. However, for women diagnosed with breast cancer there is a lack of comprehensive analyses on the effects of dietary interventions. The purpose of this study was to investigate the impact of changes in dietary behavior and body composition on breast cancer development. A comprehensive and systematic literature search of 12 electronic databases was undertaken on January 27, 2021 to identify randomized controlled trials (RCTs) of dietary interventions for breast cancer. The Cochrane risk bias assessment tool was used to evaluate the quality of the trials identified with the data analyzed by Review Manager 5.3 software. The results showed that dietary interventions probably did not modify servings of fruit (P = 0.08), fat intake (P = 0.10), total cholesterol level (P = 0.82), body weight (P = 0.08), waist circumference (P = 0.15), or waist-to-hip ratio (P = 0.32). However, a significant reduction in body mass index (P = 0.03), and hip circumference (P = 0.03), and improvement in energy intake (P = 0.02), vegetable servings (P < 0.0001), and fiber intake (P < 0.00001) were observed. Future studies should investigate the benefits of exercise in combination with dietary interventions in breast cancer patients.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1957129.

Benefits of weight loss programs for breast cancer survivors: a systematic reviews and meta-analysis of randomized controlled trials.

BACKGROUND: Obesity and weight gain have been associated with poor disease-specific and health-related outcomes in breast cancer survivors (BCS). But the benefits of weight loss in managing BCS have not been elucidated. OBJECTIVE: To evaluate the beneficial effects of weight loss programs in randomized controlled trials on BCS. METHODS: We searched English databases PubMed, the Cochrane Library, EMBASE, Scopus, Web of Science, CINAHL, and Chinese databases China National Knowledge Infrastructure (CNKI), Weipu Information Chinese Periodical Service Platform (VIP), China Biomedical Literature Service System (SinoMed), and Wanfang from the inception to January 2021 and collected randomized controlled trials (RCTs) of weight loss programs for BCS. Two reviewers independently screened the literature, extracted the data, and assessed the risk of bias in the included studies. The data synthesis was performed on RevMan (version 5.3), and the publication bias was calculated with STATA (version 15.1). RESULTS: Ten RCTs were included in the meta-analysis. The current study showed that diet and exercise interventions resulted in significant improvements in body weight (MD = - 4.43 kg, 95%CI: - 6.23 to - 2.63, P < 0.00001), waist circumference (MD = - 2.81 cm, 95%CI: - 4.37 to - 1.26, P = 0.004), hip circumference (MD = - 3.01 cm, 95%CI: - 4.24 to - 1.77, P < 0.0001), body mass index (MD = - 1.69 kg/m2, 95%CI: - 2.16 to - 1.21, P < 0.00001), systolic blood pressure (MD = - 12.12 mmHg, 95%CI: - 18.97 to - 5.27), p = 0.0005), C-reactive protein (MD = - 1.83 mg/L, 95% CI: - 2.74 to - 0.91, p < 0.0001), body fat (MD = - 1.19 kg, 95%CI: - 1.75 to - 0.63, P < 0.001), fat mass (MD = - 2.29 kg, 95%CI: - 3.12 to - 1.46, P < 0.0001), and lean body mass (MD = - 2.15 kg, 95%CI: - 3.66 to - 0.65, P = 0.005). Alternatively, compared with the effects of control interventions, weight loss programs did not affect fat-free mass, total cholesterol, low-density leptin cholesterol, glucose, insulin, and leptin (P > 0.05). CONCLUSIONS: This review summarizes the benefits of weight loss programs for BCS. The results indicated that weight loss programs could significantly improve specific anthropometric outcomes but not affect biochemical indicators. Researchers should tailor weight loss interventions to the body fat status of BCS. Evidence to support the translation of effective weight loss intervention programs into wider-scale implementation is needed to be part of routine survivorship care.

The prevalence of frailty among breast cancer patients: a systematic review and meta-analysis.

PURPOSE: Coexistence of frailty and breast cancer (BC) is related to a higher risk of hospitalization, mortality, and falls. Given the potential reversibility of frailty, investigating its epidemiology in BC is of great importance. However, estimates of the prevalence of frailty in BC patients vary considerably. We synthesized the existing body of literature on the prevalence of frailty among BC patients. METHODS: We searched English databases (Cochrane Library, PubMed, Medline, CINAHL, Embase, Scopus, and Web of Science) and Chinese databases (CNKI, WanFang, CBM, and VIP database) from the inception to April 15, 2021, and collected observational studies about the prevalence of frailty among BC patients. The robustness of the pooled estimates was validated by analysis of different subgroups, meta-regression, and sensitivity. All data were analyzed using Stata 15.1. RESULTS: In total, 4645 articles were screened and data from 24 studies involving 13,510 subjects were used in the meta-analysis. The prevalence of frailty among BC patients in individual studies varied from 5 to 71%. The pooled prevalence of frailty was 43% (95% confidence intervals (CI): 36% to 50%, I2 = 98.4%, P < 0.05). Subgroup analyses revealed that the therapeutic method, frailty scales, age, frailty stage, regions, publication years, and study quality were associated with the prevalence of frailty among BC patients. CONCLUSIONS: The prevalence of frailty among BC patients was relatively high, and the conditions of BC treatment can increase the risk of frailty. Understanding the effects of frailty on BC, especially in elderly patients, can provide the healthcare personnel with the theoretical basis for patients' management and treatment.

Correlation between serum C-peptide-releasing effects and the risk of elevated uric acid in type 2 diabetes mellitus.

Our study aimed to investigate the C-peptide-releasing effect associated with the risk of elevated serum uric acid (SUA) levels in patients with type 2 diabetes mellitus (T2DM). In the cross-sectional study, 345 patients with T2DM hospitalized at the First Affiliated Hospital of Harbin Medical University were consecutively enrolled, and their baseline data were collected. The study design used two parameters for C-peptide releasing effects: the multiplication effect of 1 h postprandial C-peptide to fasting C-peptide ratio (1hCp/FCp) and 2hCp/FCp; the incremental effect of 1hCp minus FCp (1hΔCp) and 2hΔCp. The patients with T2DM in the upper quartiles of SUA had higher FCp, 1hCp, 1hΔCp, 2hCp, and 2hΔCp. Multiple linear regression analysis revealed that after adjusting all the confounding factors, the serum C-peptide including 1hCp (ß = 5.14, p = 0.036), 1hΔCp (ß = 7.80, p = 0.010), 2hCp (ß = 4.27, p = 0.009) and 2hΔCp (ß = 5.20, p = 0.005) were still positively correlated with SUA levels in patients with T2DM. In female patients, only the 2hCp (ß = 4.78, p = 0.017) and 2hΔCp (ß = 5.28, p = 0.019) were associated with SUA level; however, in male patients, no C-peptide parameter was associated with SUA levels in T2DM (all p > 0.05). Within a certain range, the elevated SUA levels might be associated with the better C-peptide incremental effect of islet ß cell function in T2DM, especially in female patients.

LncRNA H19 via miR-29a-3p is involved in lung inflammation and pulmonary fibrosis induced by neodymium oxide.

The occupational and environmental health safety of rare earths has attracted considerable attention. In China, the rare earth neodymium oxide (Nd2O3) is extensively refined and utilized. However, the mechanisms of Nd2O3-induced lung injury are elusive. In the present study, we found that exposure of mice to Nd2O3 caused an inflammatory reaction and fibrosis in lung tissues, which was in relation to the Nd2O3-induced higher levels of the lncRNA H19 (H19), tumor necrosis factor receptor 1 (TNFRSF1A), p-p65, and p-IKKß and lower levels of miR-29a-3p. Further, in mouse monocyte macrophage leukemia cells (RAW264.7), Nd2O3 induced an inflammatory reaction, increases of H19 and TNFRSF1A levels, decreases of miR-29a-3p levels, and activation of the nuclear factor (NF)-κB signaling pathway. Further, we established that miR-29a-3p regulates TNFRSF1A expression. Up-regulation of miR-29a-3p and down-regulation of H19 blocked the Nd2O3-induced secretion of TNF-α, MIP-1α, and IL-6; the increases of TNFRSF1A levels; and activation of the NF-κB signaling pathway in RAW264.7 cells. Further, in Nd2O3-treated RAW26.4 cells, H19 inhibited the expression of miR-29a-3p, which targets TNFRSF1A, and activated the NF-κB signaling pathway to enhance the expression of TNF-α, MIP-1α, and IL-6. Moreover, for mice, up-regulation of miR-29a-3p reversed lung tissue inflammation, pulmonary fibrosis, and activation of the NF-κB signaling pathway induced by Nd2O3. In sum, the present investigation shows that H19 via miR-29a-3p is involved in lung inflammation and pulmonary fibrosis induced by Nd2O3, which is a mechanism for the Nd2O3-induced lung inflammatory response and pulmonary fibrosis. This information is useful for development of a biomarker of Nd2O3-induced lung injury.

Efficacy of auricular acupressure in maintenance haemodialysis patients: A systematic review and meta-analysis.

OBJECTIVES: To systematically evaluate the efficacy of auricular acupressure on sleep disorders, depression, pruritus, xerostomia and daily net weight gain (%) in maintenance haemodialysis patients. BACKGROUND: Auricular acupressure has been used for various complications in maintenance haemodialysis patients, such as sleep disorders, depression, pruritus and xerostomia, but the efficacy has not yet been unified. DESIGN: Systematic review and meta-analysis. METHODS: Randomised controlled trials comparing auricular acupressure intervention with non-AA intervention in maintenance haemodialysis patients were included. We searched English databases (PubMed, Cochrane Library, Embase, Web of Science) and Chinese databases (CNKI, WanFang, CBM and VIP database) from the inception to 27 November 2020. The risk of bias was assessed by the Cochrane risk of bias tool. The RevMan 5.3 software was used to perform the meta-analysis. A descriptive analysis was conducted if the data were high of heterogeneity or could not be meta-analysed. The PRISMA statement was used to report systematic review and meta-analysis. RESULTS: A total of 12 RCTs with 805 MHD patients were included. Meta-analysis showed that auricular acupressure had a significant difference for improving sleep disorders (MD = -1.97 points, 95% CI: -2.62 to -1.32, p < .0001), pruritus (MD = -1.55 points, 95% CI: -2.01 to -1.08, p < .0001), and daily net weight gain (%) (MD = -0.29, 95% CI: -0.37 to -0.21, p < .0001). The efficacy of depression and xerostomia were analysed descriptively due to insufficient data. CONCLUSIONS: The meta-analysis results indicated that auricular acupressure had a positive efficacy in maintenance haemodialysis patients to improve sleep disorders, pruritus and daily net weight gain (%). But the results should be treated conservatively on account of the low quality of included studies. Future researchers need to conduct more high-quality, large sample, multi-centre randomised controlled studies to provide a solid basis to demonstrate of the efficacy of auricular acupressure in maintenance haemodialysis patients. RELEVANCE TO CLINICAL PRACTICE: Auricular acupressure has the advantages of low cost, non-invasive and easy to be accepted by patients. This review suggested that auricular acupressure could be considered a non-pharmacological intervention for maintenance haemodialysis patients. Medical staff could teach maintenance haemodialysis patients auricular acupressure to help them self-manage some complications at home.

Complex spectral filters in silicon waveguides based on cladding-modulated Bragg gratings.

Spectral filters are important building blocks for many applications in integrated photonics, including datacom and telecom, optical signal processing and astrophotonics. Sidewall-corrugated waveguide grating is typically the preferred option to implement spectral filters in integrated photonic devices. However, in the high-index contrast silicon-on-insulator (SOI) platform, designs with corrugation sizes of only a few tens of nanometers are often required, which hinders their fabrication. In this work, we propose a novel geometry to design complex Bragg filters with an arbitrary spectral response in silicon waveguides with laterally coupled Bragg loading segments. The waveguide core is designed to operate with a delocalized mode field, which helps reduce sensitivity to fabrication errors and increase accuracy on synthesized coupling coefficients and the corresponding spectral shape control. We present an efficient design strategy, based on the layer-peeling and layer-adding algorithms, that allows to readily synthesize an arbitrary target spectrum for our cladding-modulated Bragg gratings. The proposed filter concept and design methodology are validated by designing and experimentally demonstrating a complex spectral filter in an SOI platform, with 20 non-uniformly spaced spectral notches with a 3-dB linewidth as small as 210 pm.

Low-loss off-axis curved waveguide grating demultiplexer.

Current optical communication systems rely on the use of wavelength division multiplexing (WDM) to keep up with the increasing data rate requirements. The wavelength demultiplexer is the key component to implement WDM systems. In this Letter, we design and experimentally demonstrate a demultiplexer based on a curved grating waveguide geometry that separates eight channels with a spacing of 10 nm (1249 GHz) around the central wavelength of 1550 nm. The fabricated device shows very low insertion loss (∼1dB) and a crosstalk (XT) below -25dB. This device leverages metamaterial index engineering to implement the lateral cladding on one side of the waveguide. This makes it possible to design a waveguide grating with highly directional lateral emission by operating in a regime where diffraction into the silica upper cladding is frustrated, thus suppressing losses due to off-chip radiation.

The scalp cooling therapy for hair loss in breast cancer patients undergoing chemotherapy: a systematic review and meta-analysis.

PURPOSE: To systematically assess the efficacy and side effects of scalp cooling in patients with breast cancer. METHODS: A systematic literature search was conducted in October 2020 across Cochrane Library, PubMed, Embase, CINAHL, Web of Science, Scopus, and four Chinese databases (CNKI, Wanfang, SinoMed, and VIP database). Our review included all randomized controlled trials, cohort studies, and cross-sectional studies. Two authors independently searched databases, screened studies, extracted data, and evaluated each included study's methodological quality and risk bias. Meta-analysis was performed using Stata 15.1 software package and Revman 5.3 software, with estimates of scalp cooling effect and its side effects from pooled using a random-effects model. This study has been registered in the International Prospective Register of Systematic Reviews (PROSPERO, CRD42020216224). RESULTS: In total, 755 articles were screened and data from 27 studies involving 2202 participants were used in the meta-analysis. Studies meeting inclusion and exclusion criteria were three randomized clinical trials, 12 cohort studies, and 12 cross-sectional studies. The effectiveness rate of using a scalp cooling device to protect hair was 61% (95% CI: 55 to 67%, I2 = 88%, P = 0.000). However, scalp cooling therapy's side effects are not be ignored, such as headache, dizziness, scalp pain, neck pain, feeling cold, heaviness of the head, skin rash, nausea, and overtightened strap. CONCLUSIONS: This review shows that scalp cooling devices can significantly improve the patients with breast cancer chemotherapy-induced alopecia, but the implications of its side effects provide guide for the implementation of this technology.

Spectrum-free integrated photonic remote molecular identification and sensing.

Absorption spectroscopy is widely used in sensing and astronomy to understand remote molecular compositions. However, dispersive techniques require multichannel detection, reducing detection sensitivity while increasing instrument cost when compared to spectrophotometric methods. We present a novel non-dispersive infrared molecular detection and identification scheme that performs spectral correlation optically using a specially tailored integrated silicon ring resonator. We show experimentally that the correlation amplitude is proportional to the number of overlapping ring resonances and gas lines, and that molecular specificity can be achieved from the phase of the correlation signal. This strategy can enable on-chip detection of extremely faint remote spectral signatures.

Fractional Exhaled Nitric Oxide is Associated with the Severity of Stable COPD.

The value of fractional exhaled nitric oxide (FeNO) in patients with chronic obstructive pulmonary disease (COPD) remains unclear. We aimed to assess whether FeNO is a more valuable biomarker than blood eosinophil count for identifying clinical characteristics of COPD. Stable COPD patients (n = 390) were included and stratified by FeNO and blood eosinophil counts at recruitment. The demographic characteristics, lung functions, St George Respiratory Questionnaire (SGRQ), serum inhaled allergen-specific IgE and the exacerbations in the preceding 12 months were compared. Risk factors for moderate or severe exacerbation in the preceding 12 months were examined by binary regression analysis. The cross-sectional study showed that 167 patients had high level of FeNO (≥25 ppb) and 223 in low level (<25 ppb), while 138 patients had high blood eosinophil count (≥200 cells/µL) and 252 had low (<200 cells/µL). Compared with the high FeNO group, there were higher proportion of patients with GOLD III-IV, higher SGRQ scores, more exacerbations in the preceding 12 months, and with lower positive proportion of sIgE in the low FeNO group (p < 0.05 for all). However, these phenomena above were not associated with blood eosinophil count. Finally, high FeNO level was associated with a lower moderate or severe exacerbation in preceding 12 months (RR: 0.541 [95%CI 0.319-0.917], p = 0.023). In stable COPD patients, FeNO, but not blood eosinophil count was associated with the COPD severity and allergic airway inflammation. However, the role of FeNO in guiding personalized treatment of COPD patients need to be further investigated.

Empirical model for the temperature dependence of silicon refractive index from O to C band based on waveguide measurements.

An accurate model for the silicon refractive index including its temperature and wavelength dependence is critically important for many disciplines of science and technology. Currently, such a model for temperatures above 22°C in the optical communication bands is not available. The temperature dependence in the spectral response of integrated echelle grating filters made in silicon-on-insulator is solely determined by the optical properties of the slab waveguide, making it largely immune to dimensional uncertainties. This feature renders the echelle filters a reliable tool to evaluate the thermo-optic properties of silicon. Here we investigate the temperature dependence of silicon echelle filters for the wavelength range of both O and C bands, measured between 22°C to 80°C. We show that if a constant thermo-optic coefficient of silicon is assumed for each band, as is common in the literature, the predictions show an underestimate of up to 10% in the temperature-induced channel wavelength shift. We propose and assess a model of silicon refractive index that encompasses both the wavelength and temperature dependence of its thermo-optic coefficients. We start from literature data for bulk silicon and further refine the model using the echelle filter measurement results. This model is validated through accurate predictions of device channel wavelengths and their temperature dependence, including the quadratic term, over a wide wavelength and temperature range. This work also demonstrates a new high-precision method for characterizing the optical properties of a variety of materials.

Bragg filter bandwidth engineering in subwavelength grating metamaterial waveguides.

Bragg gratings are fundamental building blocks for integrated photonic circuits. In the high-index contrast silicon-on-insulator material platform, it is challenging to accurately control the grating strength and achieve narrow spectral bandwidths. Here we demonstrate a novel Bragg grating geometry utilizing a silicon subwavelength grating (SWG) waveguide with evanescently coupled periodic Bragg loading segments placed outside the SWG core. We report experimental 3 dB filter bandwidths in a range from 8 nm to 150 pm by adjusting the distance of the Bragg loading segments from the core and the relative phase shift of the segments on the two sides of the waveguide, with a structure that has a minimum feature size of 100 nm.

Tilted subwavelength gratings: controlling anisotropy in metamaterial nanophotonic waveguides.

Subwavelength grating (SWG) structures are an essential tool in silicon photonics, enabling the synthesis of metamaterials with a controllable refractive index. Here we propose, for the first time to the best of our knowledge, tilting the grating elements to gain control over the anisotropy of the metamaterial. Rigorous finite difference time domain simulations demonstrate that a 45° tilt results in an effective index variation on the fundamental TE mode of 0.23 refractive index units, whereas the change in the TM mode is 20 times smaller. Our simulation predictions are corroborated by experimental results. We furthermore propose an accurate theoretical model for designing tilted SWG structures based on rotated uniaxial crystals that is functional over a wide wavelength range and for both the fundamental and higher order modes. The proposed control over anisotropy opens promising venues in polarization management devices and transformation optics in silicon photonics.

An ultrasensitive photoelectrochemical bioanalysis strategy for tumor markers based on the significantly enhanced signal of a bismuth oxyiodine microsphere/graphitic carbon nitride composite.

An innovative and ultrasensitive photoelectrochemical bioanalysis strategy was designed, which provided a promising method for the assay of tumor markers. The BiOI/g-C3N4 composite acted as photoelectrochemical biosensing substrate for significant signal enhancement, and CuS NPs were introduced to label signal antibodies to amplify the signal variation.

Disorder effects in subwavelength grating metamaterial waveguides.

Subwavelength grating (SWG) waveguides are integrated photonic structures with a pitch substantially smaller than wavelength for which they are designed, so that diffraction effects are suppressed. SWG operates as an artificial metamaterial with an equivalent refractive index which depends on the geometry of the structure and the polarization of the propagating wave. SWG waveguides have been advantageously used in silicon photonics, resulting in significant performance improvements for many practical devices, including highly efficient fiber-chip couplers, waveguide crossings, broadband multimode interference (MMI) couplers, evanescent field sensors and polarization beam splitters, to name a few. Here we present a theoretical and experimental study of the influence of disorder effects in SWG waveguides. We demonstrate via electromagnetic simulations and experimental measurements that even a comparatively small jitter (~5 nm) in the position and size of the SWG segments may cause a dramatic reduction in the transmittance for wide (multimode) SWG waveguides, while for narrow (single mode) waveguides this effect is negligible. Our study shows that the impact of the jitter on SWG waveguide performance is directly related to the modal confinement.