ABSTRACT
Regional ocean models require accurate weather data for atmospheric boundary conditions such as air temperature, wind speed, and direction to simulate the coastal environment. In this study, a numerical modelling framework was developed to simulate different physical, chemical, and biological processes in a semi-enclosed coastal ecosystem by integrating the Weather Research and Forecasting (WRF) model with a 3D hydrodynamic and ecosystem model (Ise Bay Simulator). The final analytic data of the global forecast system released by the National Centers for Environmental Prediction with a 0.25° horizontal resolution was used as an atmospheric boundary condition for the WRF model to dynamically downscale the weather information to a spatial and temporal fine resolution. This modelling framework proved to be an effective tool to simulate the physical and biogeochemical processes in a semi-enclosed coastal embayment. The WRF-driven ecosystem simulation and recorded Automated Meteorological Data Acquisition System (AMeDAS)-driven ecosystem simulation results were further compared with the observed data. The performance of both the recorded AMeDAS and WRF generated weather datasets were equally good, and more than 80% of the variation in bottom dissolved oxygen for shallow water and more than 90% for deep water was reproduced.
ABSTRACT
An ultracompact, bandwidth-tunable filter has been demonstrated using a silicon-on-insulator (SOI) wafer. The device is based on cascaded grating-assisted contra-directional couplers (GACDCs). It also involves the use of a subwavelength grating (SWG) structure. By heating one of the heaters on GACDCs, a bandwidth tunability of â¼6 nm is achieved. Owing to the benefit of having a large coupling coefficient between SWG and strip waveguides, the length of the coupling region is only 100 µm. Moreover, the combination of the curved SWG and the tapered strip waveguides effectively suppresses the sidelobes. The filter possesses features of simultaneous wavelength tuning with no free spectral range (FSR) limitation. A maximum bandwidth of 10 nm was experimentally measured with a high out-of-band contrast of 25 dB. Similarly, the minimum bandwidth recorded is 4 nm with an out-of-band contrast of 15 dB.
ABSTRACT
Ultra-compact mode-order converters with dielectric slots are demonstrated on a silicon-on-insulator platform. We propose a mode converter that converts the TE0 mode into the TE1 mode with an ultra-small footprint of only 0.8×1.2µm2. The measured insertion loss is less than 1.2 dB from 1520 nm to 1570 nm. To reduce the insertion loss, we further optimize the structure and design two mode converters that convert the TE0 mode into the TE1 mode and the TE2 mode with footprints of 0.88×2.3µm2 and 1.4×2.4µm2, respectively. Their measured insertion losses are both less than 0.5 dB. Additionally, the proposed devices are cascadable and scalable for high-order mode conversion.
