High-speed system for time-domain terahertz measurements
- Proprietary ECOPS technology: fast, all-electronic time delay
- One system drives up to two emitter-receiver pairs
- Scan frequency: more than 1000 pulse traces / sec (5000 traces / sec demonstrated)
- Fiber-coupled emitter and receiver antennas
- Terahertz dynamic range: ≥ 45 dB @ max. speed (higher with trace averages)
Time-domain terahertz (TD-THz) techniques have opened up new possibilities across a wide range of applications: from fundamental science to non-destructive testing of plastic composites and paint layers, and from security screening of mail envelopes to semiconductor inspection. Most of the TD-THz spectrometers developed thus far accommodate a mechanical delay stage for waveform sampling. System performance notwithstanding, the delay has remained a bottleneck in terms of measurement speed.
TOPTICA’s TeraFlash smart utilizes a scheme dubbed "electronically controlled optical sampling", briefly ECOPS (see Literature below). The approach employs two femtosecond lasers rather than just one, eliminating the need for a mechanical delay altogether. The terahertz transmitter and antenna are driven by a separate laser each. By means of a fast feedback loop, the repetition rate of the “slave” laser is phase-locked to that of the “master”. An additional modulation varies the phase difference between the two pulse trains, and therefore, the pulses of the “slave” are periodically accelerated or delayed. The net effect is equal to that of a conventional, mechanical delay stage, yet data acquisition is roughly 100 times faster!
The TeraFlash smart proves attractive for measurements on rapidly moving samples (conveyor belts, papermaking machines, extrusion lines), in particular if high spatial resolution is required. Another potential application includes measurements under rapidly changing environmental conditions. In a proof-of-principle measurement, researchers from TOPTICA and the University of Toulouse studied the properties of samples in pulsed magnetic fields, employing a table-top magnet with a peak field strength of 3 T. The ECOPS system achieved a measurement rate of 5 kHz, sufficiently fast to record more than 10 terahertz waveforms during the 2.5 ms halfwidth of the magnet pulse.
Availability: General market launch in 2017. OEM inquiries welcome.
- Additional Information
- R.J.B. Dietz et al., All fiber-coupled THz-TDS system with kHz measurement rate based on electronically controlled optical sampling, Opt. Lett. 39 (2014)
- M. Yahyapour et al., Non-contact thickness measurements with terahertz pulses, Proc. 19th Conference on Non-Destructive Testing (WCNDT), Munich, 2016
- M. Yahyapour et al., Terahertz time-domain magneto-spectroscopy using electronically controlled optical sampling, Proc. 41st International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz) 2016