Semiconductor lasers: past achievements and future challenges

The impressive development of semiconductor lasers started in 1962 with simple homojunction structures, exhibiting very large threshold currents, and only at low temperatures and under pulsed operation. Even the report of CW operation at 77 K generated strong, disbelief in the early days. Nobody would have anticipated the dramatic developments which followed, for instance, in the reduction of threshold currents. If one plots the threshold current in a logarithmic scale vs. the year, one gets a nearly linear relation which can be considered as “Moore´s Law of Optoelectronics”