Direct modulation and active mode locking of ultrahigh speed GaAlAs lasers at frequencies up to 18 GHz

It is demonstrated that an ultrahigh speed window buried heterostructure GaAlAs laser fabricated on a semi-insulating substrate can be used as a narrowband signal transmitter in the Ku band frequency range (12–20 GHz). The modulation efficiency can be increased over a limited bandwidth by a weak optical feedback. A stronger optical feedback enables one to actively mode lock the laser diode at a very high repetition rate up to 17.5 GHz, producing pulses ∼12 ps long.