Influence of delay stage positioning error on signal-to-noise ratio, dynamic range, and bandwidth of terahertz time-domain spectroscopy

2020 ◽  
Vol 59 (3) ◽  
pp. 841
Author(s):  
Shun Takagi ◽  
Shogo Takahashi ◽  
Kei Takeya ◽  
Saroj R. Tripathi
Keyword(s):  
Time Domain ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Positioning Error ◽  
Terahertz Time Domain Spectroscopy ◽  
Signal To Noise ◽  
Time Domain Spectroscopy ◽  
Noise Ratio

scholarly journals Фотопроводящий THz-детектор на основе сверхрешеточной гетероструктуры с плазмонным усилением

2020 ◽  
Vol 46 (22) ◽  
pp. 10
Author(s):  
А.В. Горбатова ◽  
Д.И. Хусяинов ◽  
А.Э. Ячменев ◽  
Р.А. Хабибуллин ◽  
Д.С. Пономарев ◽  
...  
Keyword(s):  
Time Domain ◽  
Laser Excitation ◽  
Signal To Noise Ratio ◽  
Photoconductive Antenna ◽  
Signal To Noise ◽  
Time Domain Spectroscopy ◽  
Noticeable Increase ◽  
Noise Ratio

We report on a high-sensitive THz plasmonic-enhanced photoconductive antenna (PCA)-detector based on an InGaAs/InAlAs superlattice heterostructure. A noticeable increase in the sensitivity and signal-to-noise ratio of the proposed PCA-detector is shown compared to a similar detector without plasmonic electrodes. The efficiency of plasmonic electrodes has been experimentally confirmed via pulsed THz time-domain spectroscopy by measuring the dependence of the THz amplitude of the detector’s signal on the polarization of laser excitation.

An Over 120dB Dynamic Range Linear Response Single Exposure CMOS Image Sensor with Two-stage Lateral Overflow Integration Trench Capacitors

2020 ◽  
Vol 2020 (7) ◽  
pp. 143-1-143-6 ◽  
Author(s):  
Yasuyuki Fujihara ◽  
Maasa Murata ◽  
Shota Nakayama ◽  
Rihito Kuroda ◽  
Shigetoshi Sugawa
Keyword(s):  
Linear Response ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Signal To Noise ◽  
Single Exposure ◽  
Two Stage ◽  
Noise Ratio ◽  
Maximum Signal

This paper presents a prototype linear response single exposure CMOS image sensor with two-stage lateral overflow integration trench capacitors (LOFITreCs) exhibiting over 120dB dynamic range with 11.4Me- full well capacity (FWC) and maximum signal-to-noise ratio (SNR) of 70dB. The measured SNR at all switching points were over 35dB thanks to the proposed two-stage LOFITreCs.

scholarly journals Terahertz Time-Domain Spectroscopy Based on Commercially Available 1550 nm Fabry–Perot Laser Diode and ErAs:In(Al)GaAs Photoconductors

2019 ◽  
Vol 9 (13) ◽  
pp. 2704 ◽  
Author(s):  
Kai-Henning Tybussek ◽  
Kevin Kolpatzeck ◽  
Fahd Faridi ◽  
Sascha Preu ◽  
Jan C. Balzer
Keyword(s):  
Laser Diode ◽  
Time Domain ◽  
Dynamic Range ◽  
Laser System ◽  
Industrial Applications ◽  
Thz Radiation ◽  
Full Potential ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Fabry Perot

THz time-domain spectroscopy (TDS) is a promising tool for quality control purposes in industrial applications, but the high cost and the relatively large laser sources still make it difficult to use the full potential of the technology for a decent price. In this work, a THz TDS system, which uses a commercially available Fabry–Perot laser diode emitting at 1550 nm, is presented. By dispersion compensation, pulses with a duration of 544 fs were generated, resulting in THz radiation with a bandwidth of 1.4 THz and a peak dynamic range of 56 dB with state-of-the-art ErAs:In(Al)GaAs photoconducting antennas. These results are compared with those of a conventional and expensive fiber laser system with a 90 fs pulse duration.

scholarly journals Estimation and Correction of Sampling Time Offsets in Tiadcs using Optimization Algorithm

2020 ◽  
Vol 9 (4) ◽  
pp. 1217-1222
Keyword(s):  
Optimization Algorithm ◽  
High Frequency ◽  
Performance Metrics ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Sampling Time ◽  
Signal To Noise ◽  
High Sampling ◽  
Noise Ratio ◽  
Estimation And Correction

In recent communication technologies, very high sampling rates are required for rf signals particularly for signals coming under ultra high frequency (UHF), super high frequency (SHF) and extremely high frequency (EHF) ranges. The applications include global positioning system (GPS), satellite communication, radar, radio astronomy, 5G mobile phones etc. Such high sampling rates can be accomplished with time-interleaved analog to digital converters (TIADCs). However, sampling time offsets existing in TIADCs produce non-uniform samples. This poses a drawback in the reconstruction of the signal. The current paper addresses this drawback and offers a solution for improved signal reconstruction by estimation and correction of the offsets. A modified differential evolution (MDE) algorithm, which is an optimization algorithm, is used for estimating the sampling time offsets and the estimated offsets are used for correction. The estimation algorithm is implemented on an FPGA board and correction is implemented using MATLAB. The power consumption of FPGA for implementation is 57mW. IO utilization is 27% for 4-channel TIADCs and 13% for 2-channel TIADCs. The algorithm estimated the sampling time offsets precisely. For estimation the algorithm uses a sinusoidal signal as a test signal. Correction is performed with sinusoidal and speech signals as inputs for TIADCs. Performance metrics used for evaluating the algorithm are SNR (signal to noise ratio), SNDR (signal to noise and distortion ratio), SFDR (spurious-free dynamic range) and PSNR (peak signal to noise ratio). A noteworthy improvement is observed in the above mentioned parameters. Results are compared with the existing state of the art algorithms and superiority of the proposed algorithm is verified.

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

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5389
Author(s):  
Kevin Kolpatzeck ◽  
Xuan Liu ◽  
Lars Häring ◽  
Jan C. Balzer ◽  
Andreas Czylwik
Keyword(s):  
Time Domain ◽  
Repetition Rate ◽  
Dynamic Range ◽  
Reference Signal ◽  
Thickness Measurement ◽  
Optical Signal ◽  
High Repetition Rate ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
High Repetition

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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