RF Linewidth in Monolithic Passively Mode-Locked Semiconductor Laser

We have analyzed theoretically and experimentally the linewidth of the first harmonic of the photocurrent (radio-frequency (RF) linewidth) in monolithic passively mode-locked semiconductor lasers. Due to the absence of restoring force, the timing jitter is directly related to the RF linewidth, avoiding possible underestimations made with conventional methods of phase noise measurement. The RF linewidth is also analytically related to the pulse characteristics using Haus's model. The timing stability performance of a promising two-section quantum-dot laser is presented using RF linewidth measurements. Experimental evolution of the RF linewidth with power and pulsewidth is finally compared to the analytical expression.