A mode-locked external-cavity quantum-dot laser with a variable repetition rate

A mode-locked external-cavity laser emitting at 1.17-mu m wavelength using an InAs/GaAs quantum-dot gain medium and a discrete semiconductor saturable absorber mirror is demonstrated. By changing the external-cavity length, repetition rates of 854, 912, and 969 MHz are achieved respectively. The narrowest -3-dB radio-frequency linewidth obtained is 38 kHz, indicating that the laser is under stable mode-locking operation.