Diamond-Based Sub Millimeter Backward Wave Oscillator

Making use of fabrication technology commonly used in the manufacture of liquid crystals and semiconductors, but not previously applied to vacuum devices, the diamond-based backward wave oscillator (BWO) will provide a miniature, energy efficient, electronically tunable and mass producible signal source in the sub mm wavelength regime. Fabricated within a shell of chemically vapor deposited (CVD) diamond, the BWO will employ a novel biplanar interdigital slow wave circuit. The dimensions of the BWO are estimated to be 0.600 inches long and 0.130 inches in diameter at 300 GHz, and a power output of 10 mW is predicted with a total power input of 198 mW for an overall efficiency of 5%. The electron source for the BWO will be a field emission cathode. The offerors have previously demonstrated a diamond field emitter that makes use of the negative electron affinity of diamond to obtain a threshold of emission for a gate voltage as low as 0.25 volts[1, 2]. Widely available, cost effective silicon fabrication technology will be used to integrate the BWO components into a single chip, avoiding conventional assembly techniques. The BWO would replace the present generation of bulky, power consuming signal sources that are unsuitable for space applications.