Series analysis of Signal to Noise Ratio (SNR) in active mode-locked lasers

Analysis of active mode-locked laser under the influence of asynchronous spontaneous emission (ASE) noise by using series approach is presented in this paper. Transient evolution and steady state of the mode-locked pulse are studied in details by the use of mathematical series approximating the generated pulse. The advantage of this approach as compared to classical self-consistence method is that it can be used for studying laser model in the present of the inline optically amplified noise. Series analysis results of ideal noiseless laser models are compared with that of classical method and good agreement has been obtained. Analysis of the laser model with ASE noise reveals that the large noise figure amplifier and high cavity loss degrade the signal to noise ratio (SNR). Analytical results have been validated by simulation results.