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Submitted on: 15 September 2012.
Revised on: 18 December 2012.
Accepted on: 04 January 2013.
___________________IEEE JOURNAL OF QUANTUM ELECTRONICS
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Submitted on: 15 April 2010.
Revised on: 13 May 2010.
Accepted on: 08 June 2010.
___________________IEEE JOURNAL OF QUANTUM ELECTRONICS
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