Mark Floyd, president and CEO of Siemens Information and Communications Networks US, will step down, effective today. Thomas Ganswindt, chairman of the US unit and president of the worldwide Siemens ICN Group, will oversee US operations until a permanent replacement for Floyd is chosen.   . . .   Cambridge Display Technology(CDT), developer of light-emitting polymer (LEP) technology, announced the completion of its new 1750-square-meter facility for LEP technology development. The $25 million facility includes a 600-square-meter cleanroom comprising class 1000 and class 100 areas and has already fabricated first displays on 350 x 350 mm glass substrates using spin-coating polymer deposition techniques.    . . .   JML Optical recently added two new 60" box coaters to its thin-film coating department.    . . .   Jon Herringer will manage INRAD Inc.'s new Thin Film Services business, announced at Photonics West 2002.