Electronically tunable distributed feedback lasers

The fabrication and performance characteristics of frequency tunable two‐section distributed feedback lasers are reported. The lasers are of the double channel planar buried heterostructure type and utilize a second order grating for frequency selective feedback. The laser emits in a single frequency with a cw linewidth of ∼50 MHz. The single frequency output can be tuned by ∼2 A by varying the current through one of the two sections. Electronically tunable sources of this type are potentially useful for coherent fiber transmission systems.