Folded dipole antenna for power enhancement of a terahertz photomixer

Abstract

A folded dipole antenna is proposed to increase the input impedance of an antenna for power enhancement of a terahertz integrated photomixer/antenna because the impedance of a teraherz photomixer is very high compared to the impedance of an antenna. The antenna was optimized using an electromagnetic simulator, and its resistance was increased to 2750 Ω, which is about 40 times as high as the impedance of a self-complementary broadband antenna. The optimized antenna was fabricated on low-temperature-grown GaAs (LTG-GaAs) and measured using a liquidhelium-cooled silicon bolometer. Two distributed-feedback tunable diode lasers were scanned for photomixing at frequencies from 100 to 1300 GHz in steps of 1 GHz. For stable frequency scans, the two lasers were controlled by using a feedback loop system. The measured THz output power of the proposed folded dipole antenna integrated with a THz photomixer showed resonant characteristics and was larger at the resonant frequency bands.