Ultra-fast transistor-based detectors for precise timing of near infrared and THz signals

TL;DR

This paper introduces a GaAs-based field effect transistor detector capable of simultaneously resolving near-infrared and Terahertz pulses with high speed and sensitivity, suitable for high-power pulse characterization.

Contribution

The first detector capable of simultaneous, precise timing of near-infrared and THz signals using a room-temperature GaAs FET with high dynamic range.

Findings

THz detection up to 4.9 THz demonstrated

Detection time constant shorter than 30 ps for THz pulses

Dynamic range of 65 dB/√Hz achieved

Abstract

A whole class of two-color experiments involves intense, short Terahertz radiation pulses. A fast detector that is sensitive and able to resolve both near-infrared and Terahertz pulses at the same time is highly desirable. Here we present the first detector of this kind. The detector element is a GaAs-based field effect transistor operated at room temperature. THz detection is successfully demonstrated at frequencies up to 4.9 THz. The THz detection time constant is shorter than 30 ps, the optical time constant is 150 ps. This detector is ideally suited for precise, simultaneous resolution of optical and THz pulses and for pulse characterization of high-power THz pulses up to tens of kW peak power levels. The dynamic range of the detector was as large as 65 $\pm$ 3 dB/$\sqrt{Hz}$, enabling applications in a large variety of experiments and setups, also including table-top systems.