Lightsaber

With the invention of the electricity bulb in the early 20th century, the world changed from the use of candlesticks and torch fires to a much more clean light. Since then, incandescent light bulbs were seen everywhere, ubiquitous for nearly half a century before the creation of fluorescent lamps

A review on cloud based knowledge management in higher education institutions

Knowledge Management (KM) is widely discussed by researcher and attracts many enterprisers to extract, dispense and use information in a systematic way under Knowledge Management System (KMS). New technology adoption within the knowledge management system is one of the core issue, identified by researcher and underlined as future research agenda. Cloud computing becomes the most adoptable choice for enterprisers to reduce infrastructure and maintenance cost by shifting business on the cloud. Higher Education Institutions (HEIs) are more enthusiastic about knowledge management due to its primary goal of knowledge creation and sharing. Cloud based knowledge management attract higher education institutions by changing the educational method and objectives due to innovative trends in technology. This exploratory research based on literature review for cloud-based knowledge management, targeting higher education institutions. This study highlights the benefits and challenges associated with cloud-based knowledge management system and its impact on knowledge

Design and Development of a Dual-Core Erbium Doped Amplifier for Polarization-multiplexed Signals

The extensive usage of Erbium Doped Fiber Amplifier (EDFA) in fiber optic networks creates many new configurations and technologies. Conventional optical amplifiers based on EDFA can amplify multiple channels at the same time, but within a single fiber optic core. The amplifier can be made to support multiple fibers, however the channels must be at different set of wavelengths, which is impractical since optical channels are standardized at a specific set of wavelengths. Therefore, the application of optical amplifiers are limited for one fiber core only. As an alternative, a design of an EDFA is hereby proposed. With this amplifier, it will make the network management simpler. It also provides flexibility in optical network design. In this dissertation, the design and development of EDFA is detailed and discussed. The design has made it possible to support two fibers with each one carrying the same set of wavelengths. This is achieved by taking advantage the polarization multiplexing techniques which allow a combination of lights by setting them linear and orthogonally apart. The signals co-exist in a single core EDF by differentiating both of their polarity using polarization controllers. Then it will combine through in a single core using a 3dB coupler. The combined signals are then amplified by the EDFA simultaneously, doubling the amount of signals carried by the same wavelength. The amplifier has been successfully tested at the transmission speed as high as 2.5Gbps. Moderate gain and noise figure of the EDFA was achieved at an optimum pump power for the EDF at 40mW. The transmission performance also shows tolerable polarization crosstalk due to unpolarized amplified spontaneous emission with the bit error rate showing little difference compared to that of the conventional amplifier. The results were obtained mainly through experimentation while others are through software simulation

Two-photon photoluminescence induced defects on InGaN crystal and light emitting diodes

Two-photon excitation techniques used in fabricating lines defects were done on a light emitting diode chip. Simultaneous detection of a quenched wide-gap semiconductor crystal has been observed using single- and two-photon photoluminescence. It was found at the quenched area, single-photon excitation gives photoluminescence read-out compared to two-photon excitation which no photoluminescence detected at the bandgap wavelength. This is due to the excitation states which the transition of electron for two-photon excitation to occur have been demolished by the annealing of the sample which involved two-photon quenching process. The dependency of excitation power with respective photoluminescence is elaborated to confirmed the single- and two-photon excitation photoluminescence methods

Measurement of copper nanoparticle concentration using surface plasmon resonance

In this work, the concentration of copper nanoparticles in virgin coconut oil were measured using surface plasmon resonance technique, and the gold layer was modified by using Polypyrrole Multi-Walled Carbon Nanotube composite layer. The concentration of nanoparticles and angle of resonance shifted from 0.066 mg/L to 0.71 mg/L and from 64.779° to 64.96°, respectively, and the sensitivity of sensor is about 0.01 mg/L

Numerical investigation of the performance of an SPR-based optical fiber sensor in an aqueous environment using finite-difference time domain

We investigate a surface plasmon resonance (SPR)-based optical fiber sensor using 2-D finite-difference time domain (FDTD) simulations. The optical sensor is designed by polishing a single-mode optical fiber by symmetrically removing a portion of its cladding forming two sensing regions. We analyze the effects of two physical parameters of the sensor in an aqueous medium, i.e. the thickness of the metal layer and the amount of residual cladding using numerical simulations. The results show that a good transmission dip can be obtained by optimizing these parameters. Thus, the sensor structure can be deployed as an optical biosensor in aqueous environments

Linewidth characteristics of un-cooled fiber grating Fabry–Perot laser controlled by the external optical feedback

The effect of external optical feedback (OFB) on the linewidth characteristics of un-cooled laser module is theoretically investigated. This laser that consists of a Fabry–Perot (FP) laser diode and fiber Bragg grating (FBG) realizes stable operation and relatively low-cost solution. The effects of external OFB and temperature on linewidth are calculated according to their effect on threshold carrier density (Nth). The temperature dependence (TD) of linewidth characteristics is calculated according to TD of laser parameters instead of well-known Parkovin relationship. Results show that, linewidth decreases as the external OFB reflectivity (Rext) increases. A narrow linewidth which is less than 3 kHz is obtained for Rext ≥ 0.5. In addition, the linewidth is not largely affected by temperature as compared to the DFB lasers. Also, we found that the linewidth temperature coefficient is 0.04 kHz/°C, which is small enough in comparison to 18.5 kHz/°C for the DFB laser

OCDMA multi service with zero cross correlation code in free space optics

In this paper a variable weight code for Optical Code Division Multiple Access (OCDMA) is proposed to provide differentiated services in optical network. We call it multi service zero cross correlation (MS-ZCC) where it has zero-cross correlation. Using simulation, the performance of this code is compared with the conventional variable weight (VW)-ZCC code in free space optic (FSO) environment. The newly proposed code MS-ZCC shows an improvement of 300 meters link distance for weight 2 and 8, compared to VW-ZCC

Evaluation of optical code division multiple access (OCDMA) encoding techniques for free space optics (FSO)

Free space optics (FSO) was found to have numerous applications in next generation networks, whilst optical code division multiple access (OCDMA) can be used to provide many facilities and its implementation in FSO environment has attracted several researchers. The aim of this paper is to express the achievements of these studies comprising proposed techniques in mitigating the effect of turbulence on the system. Also some defects of the mentioned studies are discussed, and suggestions for potential future researches will be provided. Furthermore, spectral amplitude coding (SAC) is implemented in FSO utilizing two different sources: light-emitting diode (LED) and laser array and their performances is compared via simulation. It is shown that considering bit error rate (BER) being equal to 10-3 as a threshold, in strong turbulence the maximum achieved distance with LED is 800 m. In the same situation using laser array can improve the distance up to 1600 m

MEH-PPV film thickness influenced fluorescent quenching of tip-coated plastic optical fiber sensors

The performance of plastic optical fiber sensors in detecting nitro aromatic explosives 1,4-dinitrobenzene (DNB) have been investigated by fluorescence spectroscopy and analyzed by using fluorescence quenching technique. The plastic optical fiber utilized is 90 degrees cut tip and dip-coated with conjugated polymer MEH-PPV poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] thin films for detection conjugants. The thicknesses of the MEH-PPV coating were varied to improvise the sensitivity whilst slowly reducing the fluorescence intensity. It was shown that fluorescence intensity from thinner film decreased by (82% in 40 s) in the presence of DNB signifying an improvement of 28% reduction with time 13 s less than that of the thicker film