Efficient direct locking of colliding pulse mode-locked lasers on semi-insulating substrate at 1.5 μm

Colliding pulse mode-locked (CPM) lasers operating at 1.5 μm and 36-GHz repetition frequency were fabricated on semi-insulating substrates. An RF electrical signal at a repetition rate of 36 GHz was injected into the saturable absorber and hybrid CPM was observed for RF powers as low as -9.0 dBm with a phase noise level of < -70 dBc/Hz at 5-kHz offset. Linewidth narrowing and pedestal suppression became pronounced for RF powers as low as 0 dBm. With an injected RF power of +8 dBm, the worst-case timing jitter was reduced from 4.8 to 0.69 ps ( 100 Hz to 10 MHz).