A high repetition rate, high power, and widely tunable THz parametric amplifier (TPA) with a KTiOPO4 crystal has been demonstrated in this work. A peak power of 1.7 kW and an average power of 89 μW have been obtained at a frequency of 5.74 THz and a repetition rate of 10 kHz. The radiation is expected to be Fourier transform limited, with a pulse duration (full width at half maximum, FWHM) of 5.4 ps and a bandwidth (FWHM) of 81 GHz, and has an M2 parameter close to the pump laser. We have also tested the TPA at a repetition rate of 100 kHz, and the results indicate that mW-level (average power) THz radiation output is feasible with a stronger pump laser that is commercially available.
With the vigorous development of China's highway construction, more and more stability problems of loose circle occurred in tunnel project, the deformation characteristics and distribution range of rock loose circle is very complex, which is of urgent need to further study. Based on geological data and construction program of Xi Shi slope tunnel, using the combined method of elastoplastic theoretical calculations and FLAC3D numerical simulation to analyze the distribution range of highway tunnel surrounding rock loose circle, and comparing it with the results of the measurements of surrounding rock deep displacement, thus, it is on the conclusion that grade IV rock loose circle of Xi Shi slope tunnel is in the range between 2.0 to 3.0m. Verifing the reliability of the method, and providing a strong guarantee for the design of support parameters.
A high repetition rate, picosecond THz parametric amplifier (TPA) with a LiNbO3 (LN) crystal has been demonstrated in this work. At 10 kHz repetition rate, a peak power of 200 W and an average power of 12 μ have been obtained over a wide range around 2 THz; at 100 kHz repetition rate, a maximum peak power of 18 W and average power of 10.8 μ have been obtained. The parametric gain of the LN crystal was also investigated and a modified Schwarz-Maier model was introduced to interpret the experimental results.
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