High-resolution THz spectrometer with kHz scan rates

Abstract

Abstract:We demonstrate a rapid scanning high-resolution THz spectrometer capable of acquiring THz field transients with 1 ns duration without mechanical delay line. The THz spectrometer is based on two 1-GHz Ti:sapphire femtosecond lasers which are linked with a fixed repetition rate difference in order to perform high-speed asynchronous optical sampling. One laser drives a high-efficiency large-area GaAs based THz emitter, the other laser is used for electro-optic detection of the emitted THz-field. At a scan rate of 9 kHz a time resolution of 230 fs is accomplished. High-resolution spectra from 50 GHz up to 3 THz are obtained and water absorption lines with a width of 11 GHz are observed. The use of femtosecond lasers with 1 GHz repetition rate is essential to obtain rapid scanning and high time-resolution at the same time.

Material thickness optimization for transmission-mode terahertz time-domain spectroscopy

“…This enables estimation of optical constants, or related quantities, of the sample from the measured pulses. Recent developments for the system mainly aim for wider bandwidth [2,3] and faster scan rates [4,5,6]. Another important aspect that needs consideration is the uncertainty in the extracted optical constants.…”

Characterization of mid-infrared femtosecond pulses [Invited]

“…In contrast, high-rate sources such as oscillators make time-domain methods such as electro-optic sampling or time-domain interferometry quite practical. Furthermore, fast-scanning methods with two oscillators at different repetition rates allow especially high data-rate characterization [64][65][66]. For limited pulse availability, such as at a free-electron laser where other synchronised pulses are difficult to produce, a self-referenced method such as those discussed in Section 3 is needed.…”

Fast and Accurate Thickness Determination of Unknown Materials using Terahertz Time Domain Spectroscopy

“…1. Therefore, by including the echo pulses and the relation (2) in the data evaluation, it is in principle possible to calculate both, the geometrical thickness and the average refractive index of an unknown material from the THz measurement as long as at least one echo pulse is present in the measured signal.…”