Advanced Techniques and Technologies of Transmission Androuting for Ultra-long Haul Ultra-broadbandtelecommunications Networks

Recent advanced techniques and associate technologies of transmission, wavelength multiplexing and channel routing for Tera-b/s photonic transport networks and their impacts on optical networking are discussed including (i) optical modulation formats and associate coding for optimising dispersion tolerance in linear and nonlinear operating regimes (ii) dispersion management and compensation techniques (iii) equalisation of gain by lumped and distributed amplification and demultiplexing sub-systems; and (iv) optical routing technology including potential applications of photonic signal processing. MULTI-Tb/s AGGREGATE OPTICAL TRANSMISSION CAPACITY Optical networking has progressed tremendously over the last few years [1]. The transmission bit rate has matured at 40 Gbps, 80 Gbps and reaching 160 Gbps. Simultaneously several optical carriers of equally spaced wavelengths across S-, Cand Lbands, are multiplexed carrying signals over several thousand kilometres leading to an aggregate capacity of multi-Tb/s in a single optical fibre. With a frequency spacing of 50 GHz or slightly wider higher number of channels could be achieved depending on the spectral efficiency of different modulation formats [2,3]. The multiplexing of several optical carriers lead to high average optical power and thus the fibre would suffer nonlinear effects, particularly the self phase modulation (SPM), four wave mixing (FWM) and cross phase modulation (XPM). Optical amplifiers, both distributed and lumped types, must also be used to compensate and equalise the optical gain over the ultra-wide band. This would result in modulation instability. Thus recently efficient line coding and efficient modulation formats attract much attention. Furthermore forward error coding techniques have been used to improve the transmission system bit-error-rate [5]. This paper describes recent novel techniques and technologies for ultra-broadband (UBB), in tera-b/s and ultra-long haul (ULH, longer than 1000 kms) transmission systems and routing of these systems for photonic transport networking. Modulation formats and photonic transmitters are discussed. In addition dispersion (chromatic and polarisation mode) management and compensation techniques in conjunction with distributed and lumped optical amplification and equalisation are described.