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Microarray-core based circular photonic crystal fiber for high chemical sensing capacity with low confinement loss

Asaduzzaman S., Ahmed K.

Optica Applicata

2017

Vol. 47, nr 1

41--49

In this article, a circular photonic crystal fiber based chemical sensor has been presented where core region is designed with an array of elliptical holes. The proposed structure is numerically investigated by using a full vectorial finite element method. From the numerical results, it is observed that introducing an array of elliptical holes helps to obtain the high relative sensitivity and realizes a low confinement loss. In addition, the increase in the value of the diameter of holes in the innermost ring enhances the relative sensitivity. Moreover, the increase in the value of the diameter of holes in the outermost ring reduces the confinement loss. In this work, we have considered an industrially valuable chemical ethanol. Simulation results disclose that the highest relative sensitivity of proposed photonic crystal fiber is 29.25% for ethanol and the confinement loss is 7.68 × 10–7 dB/m at the wavelength 1.5 µm.

Novel DWT Video Watermarking Schema

Ahmed K., El-Henawy I., Atwan A.

Machine Graphics and Vision

2009

Vol. 18, No. 3

363-380

In this paper a new video watermarking scheme is proposed which depends on 2-level Discrete Wavelet Transform decomposition of each component of an RGB video frame. The scheme embeds independent watermarks into different shots. A genetic algorithm is employed to match shots to watermarks. The scheme chooses between the HLi of red or green or blue components of each frame based on a key and embeds error correcting code into one of them. The scheme is blind. Experimental results show that the scheme is robust against attacks such as frame dropping, frame averaging, frame swapping, statistical analysis, and MPEG-2 and MPEG-4 compression. The proposed scheme uses a composite three-element key to increase the security.