Single-laser polarization-controlled optical sampling system for THz-TDS

Kolano, M.; Gräf, Benedict; Weber, Stefan; Molter, Daniel; Freymann, Georg von

doi:10.1364/ol.43.001351

Cited by 27 publications

(11 citation statements)

References 19 publications

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“…It has been shown that a smart timing management of two femtosecond lasers-known as asynchronous optical sampling (ASOPS)-could lead to pulse repetition rates in the kilohertz regime. Further improvements basing on this principle are named electronically controlled optical sampling (ECOPS) [45] and single-laser polarization-controlled optical sampling (SLAPCOPS) [46]. Both methods have the advantage to flexibly change the scanning range to match the region of interest and not to waste measurement time.…”

Section: Discussionmentioning

confidence: 99%

“…Considering a refractive index of about 1.5, this results in an upper limit of about 10 mm measurable sample thickness using standard TDS systems in reflection. Modern approaches enable the measurement of much larger delay ranges but have not been demonstrated in automotive or aviation industries tasks yet [45,46]. In some cases, the simultaneous measurement of thick and thin layers is of interest, which then can be carried out by using the TDS approach [47].…”

Section: Intermediate Devices-thick and Thin At The Same Timementioning

confidence: 99%

See 1 more Smart Citation

Terahertz Quality Inspection for Automotive and Aviation Industries

Ellrich

Bauer

Schreiner

et al. 2019

J Infrared Milli Terahz Waves

131

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Nondestructive quality inspection with terahertz waves has become an emerging technology, especially in the automotive and aviation industries. Depending on the specific application, different terahertz systems-either fully electronic or based on optical laser pulses-cover the terahertz frequency region from 0.1 THz up to nearly 10 THz and provide high-speed volume inspections on the one hand and high-resolution thickness determination on the other hand. In this paper, we present different industrial applications, which we have addressed with our terahertz systems within the last couple of years. First, we show three-dimensional imaging of glass fiber-reinforced composites and foam structures, and demonstrate thickness determination of multilayer plastic tube walls. Then, we present the characterization of known and unknown multilayer systems down to some microns and the possibility of measuring the thickness of wet paints. The challenges of system reliability in industrial environments, e.g., under the impact of vibrations, and effective solutions are discussed. This paper gives an overview of state-of-the-art terahertz technology for industrial quality inspection. The presented principles are not limited to the automotive and aviation industries but can also be adapted to many other industrial fields.

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Section: Discussionmentioning

confidence: 99%

Section: Intermediate Devices-thick and Thin At The Same Timementioning

confidence: 99%

Terahertz Quality Inspection for Automotive and Aviation Industries

Ellrich

Bauer

Schreiner

et al. 2019

J Infrared Milli Terahz Waves

131

View full text Add to dashboard Cite

show abstract

“…For example, several groups have proposed methods to eliminate the need for a mechanical ODU. These include asynchronous optical sampling (ASOPS) [6][7][8], electrically controlled optical sampling (ECOPS) [9], optical sampling by cavity tuning (OSCAT) [10,11], and single-laser polarization-controlled optical sampling (SLAPCOPS) [12].…”

Section: Introductionmentioning

confidence: 99%

Ultra-High Repetition Rate Terahertz Time-Domain Spectroscopy for Micrometer Layer Thickness Measurement

Kolpatzeck

Liu

Haring

et al. 2021

Sensors

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Terahertz time-domain spectroscopy systems driven by monolithic mode-locked laser diodes (MLLDs) exhibit bandwidths exceeding 1 THz and a peak dynamic range that can compete with other state-of-the-art systems. Their main difference compared to fiber-laser-driven systems is their ultra-high repetition rate of typically dozens of GHz. This makes them interesting for applications where the length of the terahertz path may not be precisely known and it enables the use of a very short and potentially fast optical delay unit. However, the phase accuracy of the system is limited by the accuracy with which the delay axes of subsequent measurements are synchronized. In this work, we utilize an all-fiber approach that uses the optical signal from the MLLD in a Mach–Zehnder interferometer to generate a reference signal that we use to synchronize the detected terahertz signals. We demonstrate transmission-mode thickness measurements of stacked layers of 17μm thick low-density polyethylene (LDPE) films.

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“…Moreover, the use of two femtosecond lasers makes the system less compact than the traditional THz-TDS systems. High-speed THz-TDS using a single laser was recently demonstrated through polarization-controlled optical sampling (SLAPCOPS) 16 . The system uses a unique laser consisting of two ring resonators sharing the same pump diode and gain section.…”

Section: Introductionmentioning

confidence: 99%

“…An improved timing performance can be achieved by MMLs in free-running mode since environmental effects such as vibration and temperature variations tend to affect both pump and probe repetition rates similarly. MMLs may be multiplexed in wavelength, polarization, or propagation direction 16 , 26 – 40 . In some of these systems, the difference in repetition rates is stable enough to support ASOPS-THz-TDS and dual THz comb heterodyning 30 , 37 .…”

Section: Introductionmentioning

confidence: 99%

Self-triggered Asynchronous Optical Sampling Terahertz Spectroscopy using a Bidirectional Mode-locked Fiber Laser

Baker

Yardimci

et al. 2018

Sci Rep

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We report a self-triggered asynchronous optical sampling terahertz spectroscopy system based on a single bidirectional mode-locked fiber laser and plasmonics-enhanced photoconductive nanoantennas. The fiber laser generates two optical mutually coherent pulse trains with a stable repetition rate difference, enabling time-domain terahertz spectroscopy without using any mechanical delay line, stabilization electronics, or external trigger. The resolved terahertz spectra over a 0.1–2 THz frequency range and a 30-second measurement time show more than a 70-dB dynamic range, revealing water absorption lines matching the HITRAN database, through a light-weight and compact spectroscopy setup.

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Single-laser polarization-controlled optical sampling system for THz-TDS

Cited by 27 publications

References 19 publications

Terahertz Quality Inspection for Automotive and Aviation Industries

Terahertz Quality Inspection for Automotive and Aviation Industries

Ultra-High Repetition Rate Terahertz Time-Domain Spectroscopy for Micrometer Layer Thickness Measurement

Self-triggered Asynchronous Optical Sampling Terahertz Spectroscopy using a Bidirectional Mode-locked Fiber Laser

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