In this study, U-shaped fiber optic sensors are fabricated and analyzed to measure the sensitivity of the developed sensor and optimized the detection of the refractive index (RI) of a given liquid. Identifying the authenticity of the RI is very important in food processing, chemical, liquid security and pharmacy. In this research, three types of sensors with different curvature radii (3 mm, 4 mm, and 5 mm) and different angles (30°C and 60°C) with 60 cm length of polymer fibers have been developed to characterize and analyze which type of sensor that will give optimal reading. This sensor is expected to be used for future studies such as in bioengineering, food and liquid security and chemical detection. Each sensor is tested with several types of liquids that have different densities. The development of this RI sensor is also intended to detect a suitable temperature for RI of a liquid that is between 20°C - 55°C. The research analyzed the RI sensitivity using impurity-free liquid (mineral water) and non-impurity liquid (saline water and used cooking oil). The result is measured and collected using Optical Power Meter and a 6500-input light source. The selection of this U-shaped sensor is due to the robustness of this sensor in various environments, high sensitivity, and its simple construction. This work aims to produce a low-cost and highly optimal U-shaped sensor for detecting and measuring the RI of a liquid impurity and security in any environment.
This paper demonstrates the different modelling of detection for lidar by using continuous wave and pump laser configurations as well as the signals received performance of the set test range. The configurations are developed by three main subsystems namely the transmission part that is consists of laser source, modulator, amplifier, oscillator, the target, and the receiver part that is constructed of photodetector, amplifier, filter, and signal processing. The distances tested in the simulation focuses on several ranges that is less than 1 kilometer and the wavelength used is 1550 nm. The signals obtained from both configuration modellings were analyzed and compared in terms of the tests delay, distance measurement of the target range from 20 m till 1000 m, frequency and the received signal power. Observations and analysis from the simulation results show the differences of signal pulses obtained when using continuous wave and laser pulse as well as the difference of received signal power for both configurations. Analysis shows that for lidar distance measurement, range of target also affect the received signal power where the laser pulses show detection of longer range as compared to continuous wave although for shorter distances, continuous wave displayed averaged good performance in terms of received signal power. This work will be the basis of further investigations of light detection and ranging for optimization purpose in terms of laser beam shape, fiber medium, polarization effect, optimum distance, and particle detection.
In visible optical communication over the multimode PMMA fibers, the overall cost of optical network can be reduced by deploying economical splitters for distributing the optical data signals from a point to multipoint in transmission network. The low-cost splitters shall have two main characteristics; good uniformity and high power efficiency. The most cost-effective and environmental friendly optical splitter having those characteristics have been developed. The device material is 100% purely based on the multimode step-index PMMA Polymer Optical Fiber (POF). The region which all fibers merged as single fiber is called as fused-taper POF. This ensures that all fibers are melted and fused properly. The results for uniformity and power efficiency of all splitters have been revealed by injecting red LED transmitter with 650 nm wavelength into input port while each end of output fibers measured by optical power meter. Final analysis shows our fused-taper splitter has low excess loss 0.53 dB and each of the output port has low insertion loss, which the average value is below 7 dB. In addition, the splitter has good uniformity that is 32:37:31% in which it is suitably used for demultiplexer fabrication.
The developed directional coupler using polymer optical fiber performance is studied analytically where related theories are integrated and the outcomes are analyzed. Important theories such as simplified coupled mode theory and elliptical point contacts are integrated where the parameters such as coupling length, distance between the two fibers cores and forces are varied. Using simplified coupled mode theory, coupling coefficient and coupling efficiency is obtained based on the parameters of multimode fiber coupler such as the operating wavelength, numerical apertures, coupling length and diameter of the cores. The two fibers are initially tapered at certain length at most 20 mm and attached to geometrical blocks with certain radii and the middle tapered regions of the fibers are brought closed in proximity and they are lapped to each other. Investigation of different radii of the geometrical blocks represents the effect of macro-bending when the fibers are bent when attached to the circular blocks. This concept is used to transfer the modes from first fiber to the second. Then a particular amount of load force is exerted upon one side of the blocks so that the gap is closed and leads to increment of coupling length between the two fibers. The various load force amount will give different coupling lengths and distances between the two cores, thus leading to different coupling efficiencies. Analytically the expression that represents the coupling efficiency with force is an integrated expression from simplified coupled mode theory and Hertz’s Law of elliptical point contacts. Optimized coupling efficiency obtained is as high as 70% for this study.
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