EFFECT OF NOISE ON THE POWER SPECTRUM OF PASSIVELY ANODE-LOCKED LASERS

We analyze the effects of noise on the power spectrum of pulse trains generated by a continuously operating passively mode-locked laser. The shape of the different harmonics of the power spectrum is calculated in the presence of correlated timing fluctuations between neighboring pulses and in the presence of amplitude fluctuations. The spectra at t he different harmonics are influenced mainly by the nonstationary timi ng-jitter fluctuations; amplitude fluctuations slightly modify the spe ctral tails. Estimation of the coupling term between the longitudinal cavity modes or the effective saturable absorber coefficient is made f rom the timing-jitter correlation time. Experimental results from an e xternal cavity two-section semiconductor laser ape given. The results show timing-jitter fluctuations having a relaxation time much longer t han the repetition period. (C) 1997 Optical Society of America.