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Radio Frequency Generator Using Four Wave Mixing in Cascaded Nonlinear Semiconductor Optical Amplifiers

100%
Memon M., Siraj M., Fathallah H., Khan M.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
832-834
EN
For the last three decades, the phenomenon of four-wave mixing is a significant technique for generation of light at new distinct wavelength. When two distinct laser beams (pump and probe) beat together in a non-linear medium, few modes are increased in the power at same distance from the probe and pump, as a result of four-wave mixing. In this paper, cascading structure of two semiconductor optical amplifiers produces very strong four-wave mixing. This technique is exploited to devise a tunable radio frequency signal generator. The wavelength distance between pump and probe laser beams determines the radio frequency of the generated signal. Using this scheme, it can be observed from the experimental results, that there is an increase of more than 3 dB in signal to noise ratio at 7 Gbits/sec data rate of the 60 GHz generated mm-wave signal. Moreover, the radio frequency can be tuned to hundreds of GHz by varying the distance between the pump and probe signals. This scheme will readily serve as future all optical radars. It is also a key technique for short-range communication systems for military applications. The above scheme can also be monolithically integrated.
2
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Video on Demand Over Optical Wireless Communication Links

100%
Siraj M., Memon M., Khan M.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
826-828
EN
Video on demand technology is a modern wireless communication application which requires a large bandwidth. Optical wireless networks, as a potential alternative to radio frequency, is an emerging technology that is easier to set up and provides a cost effective solution, where a physical network is difficult to deploy. Optical wireless networks can be used as a backbone to provide the much needed bandwidth for video on demand application. In this paper, Wavelength Division Multiplexing modulation scheme is proposed for the optical wireless networks due to its significance of transmitting distinct data channels at different wavelengths. Wavelength Division Multiplexing can be easily integrated with optical wireless networks, consequently resulting in an increased data rate. This paper presents a novel approach of integrating video on demand with the state of art Wavelength Division Multiplexing based optical wireless networks. Furthermore, the paper discusses the challenges and advantages over the convention modulation schemes.
3
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Two-Step Martensitic Transformation in an Aged Ti_{50}Ni_{15}Pd_{25}Cu_{10} High Temperature Shape Memory Alloys

88%
Rehman S., Khan M., Nusair Khan A., Ali L., Imran Jaffery S.
Acta Physica Polonica A
|
2015
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vol. 128
|
issue 2B
B-125-B-127
EN
Multi-step martensitic transformation in an aged Ni-rich binary NiTi shape memory alloy is considered as usual behavior during transformation from austenite to martensite phase; from (austenite) B2 to R-phase and then R-phase to B19' (monoclinic). However, for equi-atomic NiTi-based quaternary high temperature shape memory alloy, two-step martensitic transformation was detected for the first time. The Ti_{50}Ni_{15}Pd_{25}Cu_{10} high temperature shape memory alloys were investigated for the evolution of transformation temperatures at aging temperature of 550°C and 700°C. Aging at 550°C for 6 h resulted in significant reduction of phase transformation temperatures. During forward transformation from austenite to martensite, two-step martensitic transformation B2 → R and R → B19 (orthorhombic) was observed. By aging the alloy at 700°C for 6 h, no significant effect was found on phase transition behavior and transformation temperatures.
4
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A new scheme for power factor correction and active filtering for six-pulse converters loads

76%
Han Y., Khan M., Xu L., Yao G., Zhou L., Chen C.
Bulletin of the Polish Academy of Sciences: Technical Sciences
|
2009
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vol. 57
|
issue 2
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