Transform-limited pulses with time-bandwidth product as low as 0.34 ar
e obtained from a microwave modulated low-chirp MQW-DFB laser diode co
upled to a long, external cavity. Pulsewidths from 20 to 30 ps are mea
sured for repetition frequencies tunable from 2.5 to 5 GHz in steps of
approximately 100 MHz.