The optical injection-locking of an FET oscillator is accomplished by injecting the beat signal between two coherently mixed slave lasers, which are locked to different harmonics of a modulated master laser, into the FET oscillator to be locked. 120 GHz injection-locking beat signals are possible using this technique.

Optical injection locking of solid-state oscillators by frequency-multiplexed injection-locked, laser diodes

A GaAs FET structure with a high electric field region, or active region, contacted by source, gate and drain electrodes is provided which can be used for high speed optical detection or for microwave oscillator optical injection locking. The device provides for efficient coupling of optical radiation into the active region through an opening in a semi-insulating substrate used to support the device. A buffer layer between the active region and the substrate prevents leakage current to the substrate, permits a larger illumination window for improved optical coupling and provides mechanical support for the FET detector. GaAs photodetectors are also provided by eliminating the gate electrode.

Gallium arsenide burrus FET structure for optical detection

In accordance with one embodiment of the invention, a microwave signal is used to modulate a laser diode and the resultant modulated light output energy from the laser diode is applied through an optical fiber waveguide to the active solid state component in a microwave oscillator circuit such that the output signal from the microwave oscillator is phase locked to the modulation carried by the light energy. The invention allows optical injection phase locking to be achieved not only at the fundamental frequency of the modulating signal, but also at various harmonics thereof; and "on-off" switching of the microwave oscillator can be controlled simultaneously with phase locking.

System for optical injection phase locking and switching of microwave oscillators

Method of fabricating gallium arsenide burris FET structure for optical detection

Near-surface discontinuities, or flaws, within a workpiece are determined by transmitting acoustic energy into the workpiece. If a discontinuity is present the acoustic energy will resonate in the section of the material between the discontinuity and the surface. Acoustic energy emerging from the section as a result of the resonating is detected and analyzed to determine this fundamental frequency, from which the half wavelength and depth of the discontinuity may be determined. The procedure is also applicable for determining the thickness of relatively thin sheets of material.

Method and apparatus for ultrasonic detection of near-surface discontinuities

Frequency modulation by varying the intensity of light impinging on a three terminal GaAs microwave oscillator.

Joseph F Dienst

Papers

Frequency modulation by light impingement on a solid state oscillator