Fabrication and Characterization of a Leaky-Lens Photoconductive Antenna on Low-Temperature Grown GaAs Membranes

Abstract

State of the art THz pulsed commercial systems operating over large bandwidth suffer from high dispersion or low radiation efficiency due to the poor coupling between the transmitter and receiver photoconductive antennas (PCAs). In this work, we present the fabrication and characterization of a leaky lens photoconductive antenna (PCA) that has the potential to solve this problem. The presented PCA is based on a low temperature grown gallium arsenide (LT-GaAs) membrane with a 1:15 bandwidth coverage (0.1 THz – 1.5 THz), where the frequency response if constant. In order to fabricate the PCA on a LT-GaAs membrane, a novel fabrication process is developed. This process is dramatically faster than previously used processes (∼1.5 hours instead of ∼20 hours). Furthermore, an experimental validation of the radiated power together with the comparison to a standard bow-tie based PCA fabricated on the same LT-GaAs wafer is shown in this paper. We show that the PCA source on the LT-GaAs membrane is more efficient due to the enhanced leaky wave radiation. The leaky lens PCA stands out as a great candidate to improve the coupling efficiency in THz pulsed commercial systems, where the maximum laser power that can be used is limited by the dispersion in the optic fiber.