Cherenkov Phase Matched Monochromatic Tunable Terahertz Wave Generation

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Distance Measurement of a Frequency-Shifted Sub-Terahertz Wave Source

In this paper, we report the development of a frequency-shifted (FS) terahertz (THz) wave source for the non-destructive inspection of buildings. Currently, terahertz-time domain spectroscopy (THz-TDS) is the mainstream method for non-destructive inspection using THz waves. However, THz-TDS is limited by its measurement range and difficulties encountered when there is a strong frequency dependence in the absorption characteristics and refractive index of the measurement target. To address these issues, we developed a novel non-destructive approach for inspection applications using frequency-shifted THz waves. Our system uses a frequency-shifted feedback (FSF) laser as the pump light source to generate FS-THz waves; this allowed us to obtain precise distance measurements of objects over a broad range of distances. We tested a prototype FS-THz system and confirmed successful measurement of spatial distances inside a building material

Broadband terahertz light source pumped by a 1 μm picosecond laser

We obtained a frequency tunable, low-coherence, picosecond, terahertz (THz) output with a high repetition rate from a picosecond Nd:YVO₄ bounce laser in combination with tandem periodically poled stoichiometric lithium tantalate and 4'-dimethylamino-N-methyl-4-stilbazolium tosylate crystals. The frequency of the THz output was tunable in the range 2.1-7.1 THz with a linewidth of ~3.5 THz at 2.2 THz. The THz output had a maximum peak power of ~180 mW and an average power of ~0.65 μW at 3.9 THz. This system has the potential to realize ultra-high speed, THz coherence tomography.6 page(s

Broadband frequency tunable photonic sub-terahertz wave generation for spectroscopic applications

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Active gas sensing with sub-terahertz waves reflected from a wall

We present active gas sensing with a sub-terahertz (THz) spectrometer. The transmitter and receiver of the system are composed of a photonic-base source and a Schottky barrier detector, respectively, and their arrangement is monostatic. From the intensity of the absorption peak of the received sub-THz signal, the density of the sample gas (N1