Behavior and dynamics of optically controlled TRAPATT oscillators

The experimental behavior of optically controlled TRAPATT oscillators is described and results of a detailed numerical analysis of the dynamics of this optical control are presented. Wide ranges in illumination level and circuit tuning conditions are considered in order to investigate the extent of the optical control and to bring out various features of this control. It is shown that illumination of the TRAPATT diode results in increased electrical activity and serves to produce substantial shifts in oscillation frequency and power. A salient feature of this optical control is that the variations in frequency and power are dependent on the frequency to which the oscillator circuit is tuned, making it possible to adjust the characteristics of the frequency and power control. The observed behavior is shown to be the result of an optical enhancement of the carrier avalanche process which acts to control the dynamics of plasma formation and, in turn, the final density of the trapped plasma. Results of the calculations are found to be in good agreement with experiment and to indicate that further improvement in the degree of control can be obtained with optimized device structures.