Search Results (2)

A panoramic ultra-high resolution photonic integrated circuit spectrometer is under development by the authors. The architecture comprises a tunable ring resonator (RR) stage and an AWG stage. The resolution defines the bandwidth of the RR, determined by the cross-coupled power and hence the gap between the access and ring waveguides. The AWG channel frequency spacing determines the required free-spectral range (FSR) and hence the perimeter of the ring resonator. The specified <1 GHz resolution combined with an FSR of 50 GHz renders accurate simulation difficult, obstructing the design process. In this report, a simplified design rule to determine the minimum gap between straight access waveguides and a circular ring waveguide is proposed. Realistic assumptions such as the existence of local bisymmetry and adiabatic mode evolution throughout the coupling region permit a simple mode solver to determine the relationship between the cross-coupled power and the minimum gap size. A parameter extraction method is also formulated for add-drop rings equipped with two nominally identical couplers that disentangles the loss and coupling ring parameters from intensity-only transmission measurements. The proposed rule is applied to the design of ring resonators fabricated on a Si₃N₄ platform. The parameter extraction method is used to analyze the measured characterization data of the ring resonators. The results show good agreement within ~43 nm between the design rule and the gaps size determined by the parameters extracted from the measured data and provide experimental confirmation of the technological viability of the ring resonators required by the spectrometer. Full article

Due to rising consumer preference for natural remedies, the search for natural antiviral agents has accelerated considerably in recent years. Among the natural sources of compounds with potential antiviral proprieties, berries are interesting candidates, due to their association with health-promoting properties, including antioxidant, antimutagenic, anticancer, antimicrobial, anti-inflammatory, and neuroprotective properties. The past two decades have witnessed a flurry of new findings. Studies suggest promising antiviral proprieties against enveloped and non-enveloped viruses, particularly of cranberries, blueberries, blackcurrants, black raspberries, and pomegranates. The aim of this review is to assemble these findings, to list the implied mechanisms of action, and thereby point out promising subjects for research in this field, in the hope that compounds obtainable from natural sources such as berries may be used someday to treat, or even prevent, viral infections. Full article