Status of distributed feedback lasers

Unlike conventional lasers, which employ discrete end reflectors, distributed feedback (DFB) lasers utilize an internal periodic structure to produce feedback. These DFB lasers have several desirable attributes, including wavelength selectivity, longitudinal mode control, temperature stability, and well collimated output beams. They are well suited as sources in integrated optical devices. Following a review of GaAs:GaAlAs DFB and distributed Bragg reflector (DBR) lasers in an historical context, a grating coupled ring laser and a buried heterostructure DFB laser are described in detail.