Relative intensity noise of mode-locked lasers utilizing sinusoidally chirped fiber bragg grating

The relative intensity noise (RIN) of a mode-locked hybrid soliton pulse source (HSPS) utilizing a sinusoidally chirped fiber Bragg grating (FBG) is investigated using the time-domain solution of coupled wave equations and rate equations which include both spontaneous and carrier density noise. The effect of some laser diode and grating parameters on the RIN of the HSPS are also described. The numerical results show that most of the parameters affect the system operation even without noise. However, noise increases with increasing linewidth enhancement factor, gain saturation parameter, spontaneous coupling factor and field coupling factor. Noise is also extremely sensitive to the RF and DC currents. RIN reduction at the fundamental frequency (2.5 GHz) is possible in a mode-locked HSPS utilizing a sinusoidally chirped Gaussian apodized FBG when compared with a HSPS with linearly chirped gratings. 9.64 dB noise reductions are obtained when the standard parameters are used. Furthermore, it is also shown that a HSPS utilizing a sinusoidally chirped FBG produces shorter pulses than linearly chirped FBG with and without noise.