A True Optoelectronic Spectrum Analyzer for Millimeter Waves With Hz Resolution

Olvera, Anuar de Jesus Fernandez; Krause, Benedikt Leander; Preu, Sascha

doi:10.1109/access.2021.3105030

Cited by 9 publications

(10 citation statements)

References 16 publications

(26 reference statements)

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“…The acquisition card digitizes the time domain signal containing the mixing product of interest, and a DFT renders its spectrum. The observed drift is due to the passive nature of the stabilization employed in the femtosecond laser, as confirmed by further measurements [4]. This measurement underscores the capability of FreSOD as a tool to characterize the ultimate frequency stability limits of pulsed terahertz systems without the phase noise influence of an additional ESA, lock-in amplifier, or any other external reference oscillator.…”

Section: Figuresupporting

confidence: 65%

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An ultra-high-resolution technique for detection of terahertz pulses

Olvera

Krause

Betancur-Pérez

et al. 2022

2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)

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We present a novel technique for the detection terahertz pulses generated by femtosecond lasers. It features a Hz-level resolution and does not require a mechanical delay stage or a second femtosecond laser. It works by opto-electronically downconverting the individual frequency components composing the terahertz pulse. Unlike other techniques, it does not require an external spectrum analyzer or a lock-in amplifier for its implementation, although it can also be implemented using them. We believe this technique is a valuable tool to study the ultimate frequency stability of terahertz pulsed systems and the phase noise of the femtosecond lasers that drives them.

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Section: Figuresupporting

confidence: 65%

“…Fig. 5 shows a spectrogram of the 721 st component captured with an acquisition card connected to an anti-aliasing filter used after the TIA [4]. The acquisition card digitizes the time domain signal containing the mixing product of interest, and a DFT renders its spectrum.…”

Section: Figurementioning

confidence: 99%

An ultra-high-resolution technique for detection of terahertz pulses

Olvera

Krause

Betancur-Pérez

et al. 2022

2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)

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“…These have been confirmed independently with relative measurements. Additionally, the absolute frequency of the BWO was with our Hzlevel accurate EO comb system [9].…”

Section: B Psa Characterizationmentioning

confidence: 99%

“…The above described SAs are either Fourier-or Hilberttransformation based, which limits their resolution, or they are extensions to an ESA, which makes them expensive options. In a previous publication, we have demonstrated a true optoelectronic SA [9] without the requirement of an electronic SA, and a variant thereof [10] where a continuouswave (CW) electro-optic (EO) comb was employed as local oscillator in conjunction with a 1550 nm-compatible photoconductor [11] as mixer. The comparatively inexpensive CW comb enabled a Hz-level spectral resolution as demonstrated in [9] in the microwave range (50-90 GHz and [10] up to 340 GHz, yet with limitations on frequency coverage.…”

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confidence: 99%

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Photonic Spectrum Analyzer for Wireless Signals in the THz Range

2022

Self Cite

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We present an ultra-broadband and inexpensive photonic spectrum analyzer (PSA) for wireless signals with a frequency coverage from the microwave range till deep into the terahertz range. The difference frequency of two continuous-wave laser diodes works as the local oscillator frequency and a photoconductive antenna downconverts a signal under test with the aid of the optical local oscillator. With this approach we achieve a frequency coverage from less than 25 GHz to more than 1.25 THz, mostly limited by the tuning range of the lasers. No component of our spectrum analyzer needs to be interchanged in order to achieve the full tuning range, which makes our spectrum analyzer a fraction of the cost of an electronic spectrum analyzer that requires several extension modules for covering a similar frequency range. The system offers a minimum resolution bandwidth of 1.2 MHz at a displayed average noise level (DANL) as low as -113.8 dBm/Hz at 100 GHz or as low as -88.2 dBm/Hz at 1050 GHz.

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Parasitic mixing in photomixers as continuous wave terahertz sources

Kocybik,

Bauer,

Friederich

2024

Sci Rep

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We present observations of parasitic frequency components in the emission spectrum of typical photomixer sources for continuous wave (CW) terahertz generation. Broadband tunable photomixer systems are often used in combination with direct power detectors, e.g., for source and/or detector characterization. Here, spectral components besides the intended terahertz emission at the difference frequency of the two excitation lasers can significantly distort the measurement results. In this work, the appearance of parasitic mixing signals is observed in broadband measurements with a broadband antenna-coupled field-effect transistor as terahertz detector (TeraFET). The measurements reveal weaker spectral absorption features than expected and also a signal plateau towards higher frequencies, both strongly indicating a background in the detection signals. The photomixer emission is investigated in detail with a terahertz Fourier-transform infrared spectrometer (FTIR). We relate the observed parasitic frequency components with good quantitative agreement with the mode spectra of the semiconductor lasers. We also present one possible approach to overcome some of the issues, and we emphasize the importance of our findings to avoid distorted measurement results. To our knowledge, the essential aspect of parasitic mixing has so far been largely ignored in the literature where terahertz CW photomixer emitters are widely used for spectrally resolved measurements.

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A True Optoelectronic Spectrum Analyzer for Millimeter Waves With Hz Resolution

Cited by 9 publications

References 16 publications

An ultra-high-resolution technique for detection of terahertz pulses

An ultra-high-resolution technique for detection of terahertz pulses

Photonic Spectrum Analyzer for Wireless Signals in the THz Range

Parasitic mixing in photomixers as continuous wave terahertz sources

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