Terahertz frequency multipliers

The goal of this research is to explore the use of frequency multipliers to produce a practical source for frequencies near 1 THz. For this research frequency triplers to 300GHz using heterostructure barrier varactors (HBV) have been designed, fabricated and tested. Because of the symmetric C-V characteristics of HBV, only odd harmonic frequency radiations are produced and no DC bias is needed. This makes HBV tripler design inherently easier than for a Schottky diode tripler. Also, due to the stackable barrier structure of HBV diodes, large power handling ability can be achieved by just stacking more barrier layers vertically instead of putting more diodes in series like Schottky diode frequency multipliers. To date we have fabricated several batches of whisker contacted, discrete planar and integrated HBV diodes for tripling to 300 GHz (WR-3 band). These have allowed us to study the design trade-offs and perfect the fabrication processes. The resulting integrated triplers have yielded tripling efficiency to 300 GHz that is on par with the best reported in the literature. At the output frequency of 300 GHz, output power of 3.9 mW with 4.5% conversion efficiency was measured with an Erickson power meter (output power of 5.8 mW with 6.7% conversion efficiency was measured with an Anritsu WR-3 power meter).; In addition, frequency quintuplers to 210 GHz using discrete HBV diodes were also designed and tested, and the state of the art performance was obtained.; Although HBV diodes have several advantages over Schottky diodes, our research has also revealed some of their weaknesses. We decided to develop the first InGaAs Schottky triplers to WR-1.2 band using this new circuit design. An integrated anti-parallel InGaAs low barrier Schottky diode circuit on GaAs was successfully fabricated and the state of art performance was obtained. At the output frequency of 769 GHz, output power of 245 μW with at least 1% conversion efficiency was measured with an Erickson power meter. (Abstract shortened by UMI.)...