Novel Antenna-Integrated Photodiodes With Strained Absorbers Designed for Use as Terahertz Sources

We present experimental results on the performance of antenna-integrated photodiodes intended for use as photomixers to provide a tunable broadband source of terahertz (THz) radiation. In a balanced strain-absorber structure, we show that the introduction of strain has proved effective in enhancing the performance at frequencies above 500 GHz. A comparison of strained and unstrained devices confirms this claim. These structures are integrated with a range of antennas, including log periodic and slot-horn types, designed for wideband THz emission. Using the devices as photomixers for the outputs from a DFB laser and an external cavity laser in the 1550 nm telecom window, tunable emission is demonstrated over the range from 100 GHz to 1.8 THz.