We report on experimental evidence of generation and control of low spiking events in a semiconductor laser. An experiment has been carried on a semiconductor laser with an electro-optic feedback, set in a parameter range where chaos occurs. The feedback is modulated by 1 kHz and 10 kHz, frequencies, 50mV amplitudes. The dependence of the injected current on the feedback fraction is observed.

Protecting the environment from all types of pollution is a key issue, especially air pollution in particular, because of that, the ecosystem as a whole is under threat. Sudan is one of the vast African countries, covering an area of about one million square miles, and suffering from air pollution. One of the causes of this pollution is the large number of cars and factories that use gasoline. Car exhausts and factory nozzles emit kinds of gases such as carbon monoxide, lead, sulfur and other gases that contribute to air pollution. Due to the large volume of use of gasoline in cars and factories, the low quality of purification and treatment leads to the production of gases that are extremely harmful to the environment. Therefore, it is necessary to examine and determine the components of benzene used in Sudan. The technique of Laser-Induced Breakdown Spectroscopy was used to characterize the benzene samples taken from different regions, and the results showed that they contain carbon and hydrogen that are the main component of benzene, in addition many elements harmful to the environment such as (Pb, Hg and Zn), which can cause cancer diseases, and can also cause great harms to animals, plants and soil.

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One of the difficult duties in chemical industrial units is the determination of the level of liquid for real – time monitoring. Determination of this parameter is useful in process control loop. Hence present study is devoted for this purpose by employing microbend based optical fiber sensor. In this work, in order to continuously monitor liquid level in petroleum and chemical industries, an optical fiber sensor based on microbend effect was designed and implemented. The system is consist of a sensor that is composed of a microbend modulator, sensing fiber, emitting / detecting devices, in addition to liquid container unit, and an electronic circuit that was used to control the liquid level. The results showed that the laser technique is both accurate and immediate.