Frequency modulation of three-terminal Gunn devices by optical means

The three-terminal Gunn device first reported by Petzinger et al. has been frequency modulated by shining light either on the n-type gallium arsenide or the p-n junction of the device. Different sensitivities are achieved in those two modes of operation. While the device was oscillating in the bias-circuit mode at about 500 MHz, frequency variations linearly dependent on the intensity of the light have been observed in both modes of operation. The maximum shifts about 2 percent of the oscillating frequency, has been measured at a light intensity of 25 mW/cm
²
and when light was directed only on the n-type gallium arsenide. Higher-frequency shifts have been observed in the nonlinear region. The device has demonstrated capability of detecting very short light pulses, ∼ 50 ns, generated by GaAs laser.