A theory of oscillations in the output of GaAs junction lasers

A theoretical analysis is given of the time-dependent laser rate equations in the form they assume for low temperatures when it is likely that all the carriers are in the band ‘tails’, assumed to have exponential densities of states. In analogy with equations previously studied in connection with other types of laser, the solution of these equations yields damped oscillations with period and damping time in the 1 ns region. When the equations are modified by the presence of even a small concentration (compared with that of the shallow impurities responsible for band-tailing effects) of relatively deep-lying impurity levels acting as a saturable absorber, it is shown that the solutions can give the continuous oscillations observed experimentally in the output of some GaAs lasers.