Ultrahigh Speed Optical Transmission Technology Ultrahigh speed optical transmission technology is a key technology for increasing the communication capacity. In optical fibre networks the number of wavelength channels and the bit rate per wavelength channel i.e. the TDM (Time Division Multiplexing) bit rate determine the transmission capacity. Currently TDM bit rates of more than 40 Gbit s require optical signal processing (Optical Time Division Multiplexing OTDM). OTDM bit rates of up to 1.2 Tbit s have already been reported. The devices developed for ultrahigh speed optical transmission are not limited to communication applications only. They are key devices for high speed optical signal processing i.e. monitoring measurement and control and will thus give a wide technological basis for innovative science and technology. All these aspects of ultrahigh speed optical transmission technology are described in detail in this book.