We report combined active and passive mode locking of an external cavity semiconductor laser containing one absorbing and one gain diode. Compared with active mode locking alone this method requires less critical tuning of the rf modulation frequency and is not limited to operation close to threshold. Colliding pulse mode locking is achieved by placing the absorber diode at one end of the cavity so as to increase the effective absorber cross section. Streak camera measurements show that the pulse trains are free from background noise and that the 30‐ps pulses are bandwidth limited with sech2profiles.