We have investigated the KRb 480 nm system by mass-resolved resonance enhanced two-photon ionization in a cold molecular beam. The 1 (3)Delta(1), 4 (1)Sigma(+), and 5 (1)Sigma(+) <-- X (1)Sigma(+) transitions have been identified. For the 1 (3)Delta(1) and 5 (1)Sigma(+) states, the electronic term values and vibrational constants are determined experimentally for the first time. Potential energy curves of the 4 (1)Sigma(+) and 5 (1)Sigma(+) states undergo multiple avoided crossings with nearby (1)Sigma(+) states in the observed spectral region. For the 4 (1)Sigma(+) state, a vibrational numbering of the experimentally observed levels is suggested. Anomalies in vibronic structures of the 4 (1)Sigma(+) and 5 (1)Sigma(+) states are understood by comparison with high-level ab initio calculations currently available. The avoided crossing energies are also experimentally estimated.

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A detail analytical formulation is presented to study the impact of cross-phase modulation (XPM) induced phase shift on the bit error rate (BER) performance of a wavelength division multiplexing (WDM) transmission system with intensity modulation and direct detection (IM/DD). The analysis is carried out to determine the influence of XPM on the pulse shape at the fiber output at the receiving end which results in inter-symbol interference (ISI). Results evaluated at a bit rate of 10 Gbit/s show that the pulse received at the output of the direct detection receiver is much distorted due to the effect of XPM when the fiber input power level is higher than 0 dBm and there is a significant amount power penalty at a BER of 1(T 9 . Also the effects of ISI due to XPM induced phase shift is proportional to bit rate and inversely proportional to walkoff parameter. It is evident that power penalty is higher for longer fiber transmission making long distance transmission severely impaired.