All fiber-coupled THz-TDS system with kHz measurement rate based on electronically controlled optical sampling

Abstract

We demonstrate a completely fiber-coupled terahertz (THz) time-domain spectrometer (TDS) system based on electronically controlled optical sampling with two erbium-doped femtosecond fiber lasers at a central wavelength of 1560 nm. The system employs optimized InGaAs/InAlAs photoconductive antennas for THz generation and detection. With this system, we achieve measurement rates of up to 8 kHz and up to 180 ps scan range. We further achieve 2 THz spectral bandwidth and a dynamic range of 76 dB at only 500 ms measurement time.

Field Intensity Detection of Individual Terahertz Pulses at 80 MHz Repetition Rate

“…This concept usually includes a time delay, which is either realized with a mechanical stage or by synchronizing the pulse trains of two lasers. Whilst mechanical delays achieve measurement rates of 10-500 Hz (i.e., pulse traces per second) [4,5], systems based on synchronized repetition rates reach into kilohertz regimes [6][7][8]. Yet, in both cases, the velocity of the time delay remains the bottleneck in terms of attainable data rates.…”

Femtosecond terahertz time-domain spectroscopy at 36 kHz scan rate using an acousto-optic delay

“…First approaches included loudspeaker diaphragms [17] or rotating mirrors [18,19], which increased acquisition speeds to a few tens of Hz. All-optical schemes such as asynchronous optical sampling (ASOPS) [20], electrically controlled optical sampling (ECOPS) [21][22][23], or optical sampling through cavity tuning (OSCAT) [24] have greatly advanced the field and enabled scan rates of up to 8 kHz [22]. Specific challenges of these techniques include jitter and dead times when using two cavity-stabilized lasers (ASOPS), dispersion of long fiber branches (OSCAT), or complex intra-cavity elements in the laser source (ECOPS).…”

Towards Quality Control in Pharmaceutical Packaging: Screening Folded Boxes for Package Inserts

“…Mechanical delays record 10-500 pulse traces/second at most [8,9]. Novel schemes dubbed ASOPS (Basynchronous optical sampling^) [10][11][12] and ECOPS (Belectronically controlled optical sampling^) [13,14] replace the mechanical delay by two synchronized short-pulse lasers. While these concepts have proven capable of single-kilohertz data rates, they still fall short of the demands for Bultrafast^in-line screening.…”