Spontaneous noise effect on mode-locked external cavity lasers with chirped grating

The noise of mode-locked hybrid soliton pulse source (HSPS) is analyzed by couple-mode equations including spontaneous emission noise. Relative intensity noise (RIN) is calculated using numerical solutions of these equations. It is found that a noise peak in the RlN spectrum locates at the fundamental frequency and this peak is a little broader. In this range high noise affects the operation of device, so transform limited pulses are not obtained. It is also found that RIN of chirped gratings is low compared to unchirped gratings.