Semiconductor lasers will find an increasing use in future computer interconnect circuits. This application will see large numbers (thousands) of lasers used in a single computer. Because of the large number involved it will be mandatory to develop a new generation of lasers with ultralow threshold currents, Ith smaller than 0.1 mA. Such lasers are theoretically possible by resorting to quantum confined structures such as quantum well and quantum wire configurations embedded in optimized optical structures. We review the basic physical theory and the first round of experiments which lead to Ith smaller than 0.6 mA.