[1] Institute of Microelectronics and Optoelectronics,
[2] Warsaw University of Technology,undefined
[3] 00-662 Warsaw,undefined
[4] ul. Koszykowa 75,undefined
[5] Poland,undefined
[6] National Institute of Telecommunications,undefined
[7] 04-894 Warsaw,undefined
[8] ul. Szachowa 1,undefined
[9] Poland (Fax: +48-22/628-8740,undefined
[10] E-mail: p.witonski@elka.pw.edu.pl; p.szczepanski@imio.pw.edu.pl),undefined