Next generation 15 µm terahertz antennas: 
mesa-structuring of 
InGaAs/InAlAs photoconductive layers

Abstract

Mesa-structuring of InGaAs/InAlAs photoconductive layers is performed employing a chemical assisted ion beam etching (CAIBE) process. Terahertz photoconductive antennas for 1.5 microm operation are fabricated and evaluated in a time domain spectrometer. Order-of-magnitude improvements versus planar antennas are demonstrated in terms of emitter power, dark current and receiver sensitivity.

Terahertz-time domain spectrometer with 90 dB peak dynamic range

“…A strip-line antenna geometry with a 100 μm photoconductive gap was chosen for the emitter, and a dipole geometry with 10 μm gap for the receiver. Both transmitter and receiver feature a mesastructured gap region as detailed in [13].…”

“…In the past, terahertz pulses were mainly generated with GaAs photoconductive switches, which required laser excitation below 870 nm and often involved complex Ti:Sapphire lasers. With the advent of 1.5 μm fiber lasers and recent InGaAs/InAlAs-based terahertz emitters [13], a trend towards telecom-based technology has become evident. Terahertz spectrometers operating at 1.5 μm take full advantage of mature and costefficient telecom components and are thus well suited for real-world applications [14].…”

Continuous Wave Terahertz Systems Based on 1.5 μm Telecom Technologies

“…Significant further improvements have been achieved by mesa-structured antennae [19] with electrical side contacts (Fig. 6, right).…”

All fiber THz spectrometer for plastics industry

“…Femtosecond fiber lasers are more efficient and typically less-expensive than Ti:Sapphire based lasers with emission wavelength around 800 nm. Recently developed LT-InGaAs material [5] with subps carrier life time and sensitivity around 1.55 µm have sped up the development of all-fiber THz spectrometer. Up-to-date such fiber coupled THz spectrometers for industrial applications include external mechanical delay lines.…”