Narrow microwave pulse generation by optical enhancement of TRAPATT oscillations

The generation of narrow, high-power microwave pulses has been achieved by illuminating a TRAPATT diode with narrow optical pulses from a GaAlAs DH laser. Tuning the oscillator circuit to a frequency substantially above the usual operation frequency of the diode was found to result in low-level oscillation during the unilluminated portions of the TRAPATT bias pulse and a strong enhancement (up to 20 dB) of the oscillation during the optical pulse. Experimental results on the generation of 35 W pulses as narrow as 25 ns (25 RF cycles) at 1 GHz, with a rise- and fall-time of 2 ns (2 RF cycles) and excellent pulse-to-pulse stability are presented. The physical mechanism of optical enhancement is explained with results from detailed TRAPATT numerical calculations.