High-Performance Silicon-Based Multiple Wavelength Source

We demonstrate a stable CMOS-compatible on-chip multiple-wavelength source by filtering and modulating individual lines from a frequency comb generated by a microring resonator optical parametric oscillator.. We show comb operation in a low-noise state that is stable and usable for many hours. Bit-error rate measurements demonstrate negligible power penalty from six independent frequencies when compared to a tunable diode laser baseline. Open eye diagrams confirm the fidelity of the 10 Gb/s data transmitted at the comb frequencies and the suitability of this device for use as a fully integrated silicon-based WDM source.Comment: 3 pages, 3 figure

Evaluation of a dietary screener: The Mediterranean Eating Pattern for Americans tool

Background: Evidence exists for an association between accordance with a Mediterranean diet pattern and slower rates of cognitive decline. However, an ‘Americanized’ version of the Mediterranean diet screener is needed to assess accordance in the USA. Thus, the Mediterranean Eating Pattern for Americans (MEPA) tool was developed to assess accordance with a Mediterranean-like food pattern when time is limited. The present study aimed to determine whether the MEPA screener captured the key elements of the Mediterranean diet compared to the more comprehensive food frequency questionnaire (FFQ). Methods: The study comprised a cross-sectional study in which 70 women completed both the VioScreen™ FFQ (Viocare, Princeton, NJ, USA) electronically and the 16-item MEPA screener, either electronically or by telephone, aiming to evaluate the inter-method reliability of the proposed screener. The convenience sample included patients (n = 49) and healthcare providers (n = 21) recruited from a tertiary care medical center. Results: The overall score from the MEPA screener correlated with corresponding overall MEPA FFQ score (ρ = 0.365, P = 0.002). Agreement between screener items and FFQ items was moderate-to-good for berries (κ = 0.47, P \u3c 0.001), nuts (κ = 0.42, P \u3c 0.001), fish (κ = 0.62, P \u3c 0.001) and alcohol (κ = 0.64, P \u3c 0.001), whereas those for olive oil (κ = 0.33, P = 0.001) and green leafy vegetables (κ = 0.36, P = 0.0021) were fair. Usual intakes of potassium, magnesium, vitamin C, saturated fat, selected carotenoids, folate and fiber derived from the FFQ varied with MEPA screener scores in the anticipated directions. Conclusions: The MEPA screener captures several components of the Mediterranean style pattern, although further testing of the MEPA screener is indicated

Strong polarization mode coupling in microresonators

We observe strong modal coupling between the TE00 and TM00 modes in Si3N4 ring resonators revealed by avoided crossings of the corresponding resonances. Such couplings result in significant shifts of the resonance frequencies over a wide range around the crossing points. This leads to an effective dispersion that is one order of magnitude larger than the intrinsic dispersion and creates broad windows of anomalous dispersion. We also observe the changes to frequency comb spectra generated in Si3N4 microresonators due polarization mode and higher-order mode crossings and suggest approaches to avoid these effects. Alternatively, such polarization mode-crossings can be used as a novel tool for dispersion engineering in microresonators.Comment: Comments are very welcome (send to corresponding author

Second-Harmonic Generation in Silicon Nitride Ring Resonators

The emerging field of silicon photonics seeks to unify the high bandwidth of optical communications with CMOS microelectronic circuits. Many components have been demonstrated for on-chip optical communications, including those that utilize the nonlinear optical properties of silicon[1, 2], silicon dioxide[3, 4] and silicon nitride[5, 6]. Processes such as second harmonic generation, which are enabled by the second-order susceptibility, have not been developed since the bulk $\chi^{(2)}$ vanishes in these centrosymmetric CMOS materials. Generating the lowest-order nonlinearity would open the window to a new array of CMOS-compatible optical devices capable of nonlinear functionalities not achievable with the?$\chi^{(3)}$ response such as electro-optic modulation, sum frequency up-conversion, and difference frequency generation. Here we demonstrate second harmonic (SH) generation in CMOS compatible integrated silicon nitride (Si3N4) waveguides. The $\chi^{(2)}$ response is induced in the centrosymmetric material by using the nanoscale structure to break the bulk symmetry. We use a high quality factor Q ring resonator cavity to enhance the efficiency of the nonlinear optical process and detect SH output with milliwatt input powers.Comment: 4 pages, 3 figure

Disclosure of Maternal HIV Status to Children: To Tell or Not To Tell . . . That Is the Question

HIV-infected mothers face the challenging decision of whether to disclose their serostatus to their children. From the perspective of both mother and child, we explored the process of disclosure, providing descriptive information and examining the relationships among disclosure, demographic variables, and child adjustment. Participants were 23 mothers and one of their noninfected children (9 to 16 years of age). Sixty-one percent of mothers disclosed. Consistent with previous research, disclosure was not related to child functioning. However, children sworn to secrecy demonstrated lower social competence and more externalizing problems. Differential disclosure, which occurred in one-third of the families, was associated with higher levels of depressive and anxiety symptoms. Finally, knowing more than mothers had themselves disclosed was related to child maladjustment across multiple domains. Clinical implications and the need for future research are considered

A Silicon-Based Monolithic Optical Frequency Comb Source

Recently developed techniques for generating precisely equidistant optical frequencies over broad wavelength ranges are revolutionizing precision physical measurement [1-3]. These frequency "combs" are produced primarily using relatively large, ultrafast laser systems. However, recent research has shown that broad-bandwidth combs can be produced using highly-nonlinear interactions in microresonator optical parametric oscillators [4-11]. Such devices not only offer the potential for developing extremely compact optical atomic clocks but are also promising for astronomical spectroscopy [12-14], ultrashort pulse shaping [15], and ultrahigh-speed communications systems. Here we demonstrate the generation of broad-bandwidth optical frequency combs from a CMOS-compatible integrated microresonator [16,17], which is a fully-monolithic and sealed chip-scale device making it insensitive to the surrounding environment. We characterize the comb quality using a novel self-referencing method and verify that the comb line frequencies are equidistant over a bandwidth that is nearly an order of magnitude larger than previous measurements. In addition, we investigate the ultrafast temporal properties of the comb and demonstrate its potential to serve as a chip-scale source of ultrafast (sub-ps) pulses