Fiber Coupled Transceiver with 6.5 THz Bandwidth for Terahertz Time-Domain Spectroscopy in Reflection Geometry

Abstract

We present a fiber coupled transceiver head for terahertz (THz) time-domain reflection measurements. The monolithically integrated transceiver chip is based on iron (Fe) doped In0.53Ga0.47As (InGaAs:Fe) grown by molecular beam epitaxy. Due to its ultrashort electron lifetime and high mobility, InGaAs:Fe is very well suited as both THz emitter and receiver. A record THz bandwidth of 6.5 THz and a peak dynamic range of up to 75 dB are achieved. In addition, we present THz imaging in reflection geometry with a spatial resolution as good as 130 µm. Hence, this THz transceiver is a promising device for industrial THz sensing applications.

High-throughput terahertz imaging: progress and challenges

“…As a result, high-SNR and broadband operation can be maintained for each pixel, even at a low optical probe budget for a large image sensor array 235 , 236 . With the development of short-carrier-lifetime, high-mobility, photo-absorbing semiconductors at ~1550 nm wavelength 239 , 240 , the realization of telecommunication-compatible photoconductive image sensor arrays integrated with femtosecond fiber lasers is another direction that could significantly reduce the cost, size, and complexity of future THz-TDS systems. To achieve faster imaging speeds, advanced 2D readout integrated circuits as well as non-mechanical time-domain sampling methods (e.g., ASOPS and ECOPS) can be used in conjunction with the photoconductive image sensor arrays.…”

A Comparison of Continuous-Wave and Pulsed Free Space 2-Port Photonic Vector Network Analyzers for Terahertz Characterization

“…THz sources and receivers based on photonic approaches have improved immensely in recent times, which has been the basis of constructing exceptional THz characterization systems for both pulsed and continuous-wave (CW) varieties, making them excellent candidates for PVNA concepts. THz systems under pulsed operation have been reported to reach a bandwidth of 6.5 THz [2], [3], and for CW operation till 4 THz [4].…”

A Fully Optoelectronic Continuous-Wave 2-Port Vector Network Analyzer Operating From 0.1 THz to 1 THz

“…Since lasers can easily be tuned to exhibit any frequency difference between zero and several THz, the only limitation in frequency coverage is imposed by the carrier dynamics in the photomixer [2]. Still, bandwidths exceeding 6.5 THz have been demonstrated with telecom-wavelength lasers in pulsed systems and beyond 4 THz [3], [4] in continuous-wave (CW) systems [5]. The use of telecom-wavelength lasers makes the opotelectronic systems even less expensive, and allows to implement sophisticated systems with advanced capabilities, such as optical frequency combs, which enable Hz-level terahertz linewidths and resolution [6], [7].…”