optical communication network based on the wdm system the photonic cross connector system includes an optical coupler branching an input optical signal into a plurality of paths a wavelength selective switch extracting at least one wavelength signal from the input optical signal and outputting the extracted wavelength signal to at least one port a wdm multi casting apparatus simultaneously copying and reproducing the input optical signal into different wavelengths and changing modulation methods of the input optical signal into different types of modulation methods an optical transmitter and or receiver branching and coupling the input optical signal and a control system controlling the optical coupler the wss the wdm multicasting apparatus and the optical transmitter and or receiver application_number US 74556507 A description the present invention will now be described more fully with reference to the accompanying drawings in which exemplary embodiments of the invention are shown the invention may however be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein rather these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art in the drawings the thicknesses of layers and regions are exaggerated for clarity fig2 a and 2b and fig3 a through 3d are block diagrams and a graph illustrating basic functions of photonic cross connector systems according to embodiments of the present invention fig2 a.