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In this work different silicon photonic devices, including straight waveguides, multi-mode interference devices and Mach-Zehnder interferometers, were fabricated and characterized on hot-wire chemical vapor deposition (HWCVD) silicon nitride (SiN) layers deposited at temperatures below 350 °C. These layers presented a hydrogen concentration of 13.1%, which is lower than that achieved with plasma enhanced chemical vapor deposition at these deposition temperatures. The lowest reported optical propagation losses of 6.1 dB/cm and 5.7 dB/cm, 1550 nm and 1310 respectively, for straight SiN waveguides prepared by HWCVD was measured. We demonstrated that silicon nitride SiN, prepared using HWCVD, is a viable material for silicon photonics fabrication.

Brunei Darussalam is largely covered by the tropical rainforest. Around 16% of Brunei total land area is Peatland. This peatland is under the protection of the Heart of Borneo initiative. This peatland forest plays a very important role in the region’s rainforest ecosystem. However, this type of forest is vulnerable to fire outbreak, and hence the forest needs to be sustained. By using an Internet of Things (IoT) -based remote monitoring system, peat swamp forest areas can be monitored for long term management and short-term natural disaster preparedness. The proposed monitoring system is a solar-powered system equipped with built-in Long Range (LoRa) network to allow the data collection via a gateway. The system is designed to measure environmental conditions such as soil and water temperature, soil moisture, water level, wind direction and atmospheric humidity and pressure. The data collected by the system is programmed to be displayed on a dashboard which can be viewed remotely by respective agencies. The proposed system has been lab-tested on various conditions of peat soils giving measurement results which are usable for data reference.

Amorphous silicon (a-Si) is considered as one of the potential materials for multi-layer photonics due its high refractive index, linear and non-linear optical properties. This makes a-Si integration compatible with the Silicon-on-Insulator (SOI) photonics by increasing circuit density at each optical device layer. However, the high absorption loss of a-Si would require hydrogenation to passivate the dangling bonds for low loss optical waveguide interconnects and coupling of light between optical layers. Without an efficient passivation process, optical loss per layer would be too high for a viable multi-layer photonic platform. Therefore, we have developed a low temperature process hydrogenated a-Si (a- Si:H) with Hot-Wire Chemical Vapour Deposition (HWCVD) method that is compatible with back-end-of-the-line (BEOL) integration with active photonic or electronic layers. This work describes the experimental control of deposition temperature to achieve low loss a-Si:H waveguiding layer and the inter-layer waveguide coupling structures. Our latest results show a-Si:H deposited at 230 oC has the lowest propagation loss of 0.7 dB/cm for a sub-micron ridge waveguide at 1550 nm wavelength and 45 dB cross-talk isolation between two waveguides separated by 1 μm of SiO2 layer.

The need for the research breakthrough in terms of the underlying electronic components have been rising due to the limitations of the current technology. Several alternative methods for digital circuits are needed, thus silicon photonics could be the answer. This paper presents the design of a digital 2 to 4 electro-optic line decoder based on the photonic micro-ring resonator as its core component. This work provides the design principle of the proposed digital decoder, together with the demonstration and simulation of the time varying operation with the speed of 5Gbps. The performance of the proposed line decoder is shown by clear output timing diagrams.

A CMOS compatible three-dimensional (3D) integrated photonics circuit for multilayer silicon photonics is reported. Slopes with angles between 10o and 15° were created in the oxide layer using single step wet etching to connect the two Si waveguide layers. Amorphous Si (a-Si) deposited using hot wire chemical vapor deposition (HWCVD) at a temperature of 230°C was used to fabricate the device. Losses of 0.5 dB/slope were measured in the slope waveguides at 1310 nm wavelength. As a demonstration, we propose a 4x4 network switch using a-Si based vertical directional coupler.

In future smart grids many converters are linked in parallel to supply the electrical demands. To distribute the load demand between different converters a control strategy is a necessity. To control such a system, the control signals need to be distributed between the units. Using conventional wiring is impractical. Communication networks could replace the wiring systems, however, the inevitable time delay leads to poor performance of the system and jeopardise the stability. The intelligent optimization approaches can be used to optimize the performance of the system. In this paper we present the implementation of the grey wolf optimizer (GWO) technique to optimize the performance of a parallel DC-DC converters with communication delay in the control signals. The effectiveness of the GWO is superior to the particle swarm optimization.

Robotics and artificial intelligence are the basic building blocks for industry revolution 4.0. The intelligent optimization techniques have been recently used to solve complex engineering problems. The robotics is one of the fields that intelligent optimization techniques can be applied in both controller design and motion planning. In this paper, we introduce the application of artificial bee colony for tuning the PID controllers for a teleported 2 Degree-of-Freedom robot manipulator. The presence of the time delay degrades the performance of the system or at worst leads to system instability. The performance of the 2DOF manipulator has been optimized using the nonlinear model with artificial bee colony algorithm (ABCA). The performance of the 2DOF robot using ABCA optimization has been compared with the performance of the robot using particle swarm optimization algorithms and the ABCA showed better performance.

The recent developments in computing and communication networks paved the way to the Industry Revolution 4.0. In this paradigm different devices are communicating using cheap communication networks to form a networked control system. Networked control systems have two problems, which are data loss and time delay. Not considering these imperfections result in a poor performance or losing the system's stability. Determining the delay margin for the networked control system is a vital step in the controller design. In this paper, we present an accurate method for determining the time delay for a networked control of a DC motor. The transcendental characteristics equation is converted to a frequency-dependent polynomial. Then the the binary iteration algorithm and sweeping test are used to determine the crossing frequencies and hence the delay margin is accurately computed. The results are compared with the results of the latest papers and the sweeping test and the binary iteration prove to give exact values for the delay margin with less computation.

We present interlayer slope waveguides, designed to guide light from one level to another in a multi-layer silicon photonics platform. The waveguide is fabricated from hydrogenated amorphous silicon (a-Si:H) film, deposited using hot-wire chemical vapor deposition (HWCVD) at a temperature of 230°C. The interlayer slope waveguide is comprises of a lower level input waveguide and an upper level output waveguide, connected by a waveguide on a slope, with vertical separation to isolate other crossing waveguides. Measured loss of 0.17 dB/slope was obtained for waveguide dimensions of 600 nm waveguide width (w) and 400 nm core thickness (h) at a wavelength of 1550 nm and for transverse electric (TE) mode polarization.

We demonstrate low-loss hydrogenated amorphous silicon (a-Si:H) waveguides by hot-wire chemical vapor deposition (HWCVD). The effect of hydrogenation in a-Si at different deposition temperatures has been investigated and analyzed by Raman spectroscopy. We obtained an optical quality a-Si:H waveguide deposited at 230°C that has a strong Raman peak shift at 480 cm−1, peak width (full width at half-maximum) of 68.9 cm−1, and bond angle deviation of 8.98°. Optical transmission measurement shows a low propagation loss of 0.8 dB/cm at the 1550 nm wavelength, which is the first, to our knowledge, report for a HWCVD a-Si:H waveguide.

We demonstrate low temperature hot-wire chemical vapor deposition of low loss a-Si:H wire waveguides. We achieved propagation loss of 0.65 dB/cm at TE polarized $1.55 \ \mu \mathrm{m}$ wavelength for waveguides deposited at 230°C.

We present an interlayer slope waveguide, designed to guide light from one level to another level in a multilayer silicon photonics platform. The waveguide is fabricated using HWCVD a-Si:H at 350oC. Measured loss of 0.5 dB/slope was obtained at a wavelength of 1550 nm and for TE mode polarization.

We present the design, simulation and measurements of broadband gratings couplers with a variable grating pitch. The measured 3 dB bandwidth was over 110 nm. The gratings employ diamond-shaped sub-wavelength grating (SWG) structures for dispersion control and a varying pitch along the transmission axis.

Simple fabrication of low-loss Si/SiO2 waveguides with a flat side wall is proposed. Waveguides oriented to the direction on the Si (110) plane are fabricated by anisotropic wet etching and the lowest propagation loss is 1.4 dB/cm.