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Article Abstract
We demonstrate a terahertz asynchronous optical sampling (THz-ASOPS) spectrometer incorporating a lock-in amplifier. The experimental setup employs a high-voltage pulse generator to drive a photoconductive antenna emitter, generating precisely modulated terahertz pulses that are subsequently detected by a photoconductive antenna detector. The detection system features a two-stage amplification process: initial signal amplification through a low-noise current preamplifier, followed by processing with a digital lock-in amplifier. Experimental characterization demonstrates significant performance enhancements, with a 3-fold improvement in the time-domain peak signal-to-noise ratio and a 5 dB increase in the spectral dynamic range. These results substantiate the effectiveness of the lock-in detection approach in enhancing THz-ASOPS spectroscopic performance.
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| http://dx.doi.org/10.1364/OE.562343 | DOI Listing |
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We demonstrate a terahertz asynchronous optical sampling (THz-ASOPS) spectrometer incorporating a lock-in amplifier. The experimental setup employs a high-voltage pulse generator to drive a photoconductive antenna emitter, generating precisely modulated terahertz pulses that are subsequently detected by a photoconductive antenna detector. The detection system features a two-stage amplification process: initial signal amplification through a low-noise current preamplifier, followed by processing with a digital lock-in amplifier.
View Article and Find Full Text PDFThis study presents the utilization of asynchronous optical sampling (ASOPS) terahertz spectroscopy with commercially available Ti:Sapphire lasers, eliminating the need to stabilize the repetition frequency. Our postprocessing algorithm, which utilizes the multiplied repetition frequency difference as a calibration signal, effectively corrected the jitter, enabling broadband (2.5 THz) spectroscopy with a high spectral resolution (82 MHz).
View Article and Find Full Text PDFArticle Synopsis
- Asynchronous optical sampling (ASOPS) is effectively used to measure terahertz (THz) bandwidth pulses in coplanar waveguides with integrated photoconductive switches for signal excitation and detection.
- The ASOPS technique shows high performance, able to capture full THz time-domain traces at up to 100 Hz, with a dynamic range that peaks at 40 dB for short measurements and increases to 88 dB for longer durations.
- This research paves the way for advancements in real-time video-rate imaging and THz sensing applications, demonstrating the capability of ASOPS to achieve sufficient dynamic range for future THz spectroscopy measurements.
THz waves are promising wireless carriers for next-generation wireless communications, where a seamless connection from wireless to optical communication is required. In this study, we demonstrate carrier conversion from THz waves to dual-wavelength NIR light injection-locking to an optical frequency comb using asynchronous nonpolarimetric electro-optic downconversion with an electro-optic polymer modulator. THz wave in the W band was detected as a stable photonic RF beat signal of 1 GHz with a signal-to-noise ratio of 20 dB via the proposed THz-to-NIR carrier conversion.
View Article and Find Full Text PDFWe demonstrate a jitter correction method for asynchronous optical sampling (ASOPS) terahertz (THz) time-domain spectroscopy using two free-running oscillators. This method simultaneously records the THz waveform and a harmonic of the laser repetition rate difference, , to monitor the jitter information for software jitter correction. By suppressing the residual jitter below 0.
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