Dexian Yan, Yuye Wang, Degang Xu, Pengxiang Liu, Chao Yan, Jia Shi, Hongxiang Liu, Yixin He, Longhuang Tang, Jianchen Feng, Jianqin Guo, Wei Shi, Kai Zhong, Yuen H. Tsang, Jianquan Yao. High-average-power, high-repetition-rate tunable terahertz difference frequency generation with GaSe crystal pumped by 2 μm dual-wavelength intracavity KTP optical parametric oscillator[J]. Photonics Research, 2017, 5(2): 82
- Photonics Research
- Vol. 5, Issue 2, 82 (2017)
Fig. 1. Experimental setup of the THz DFG with GaSe crystals.
Fig. 2. (a) Output power of the Nd:YAG laser and 2 μm KTP OPO versus electric input power as well as 1.06 to 2 μm dual-wavelength conversion efficiency. (b) Angle tuning characteristics of the KTP OPO. The blue circles and the red solid line represent the experimental and theoretical results, respectively. Triangles indicate the 2 μm dual-wavelength laser power with respect to related PM angles of KTP.
Fig. 3. (a) Dual-wavelength spectra of the 2 μm pump source of the DFG (the insets show the FWHM of the two wavelengths). (b) Temporal pulse profile for the combined dual wavelengths and the two independent separated wavelengths of 2118.1 and 2140.5 nm. The inset shows the pulse shape of the 1.06 μm laser.
Fig. 4. THz wavelengths versus external PM angles. Inset: THz frequency versus external PM angles. Circles and the solid curve represent the experimental and theoretical results, respectively. Squares and triangles represent the 2 μm wavelength used for DFG THz.
Fig. 5. (a) THz output voltage versus THz frequency for two GaSe crystals with different lengths under 2 μm dual-wavelength pump power of about 950 mW. (b) Calculated THz intensity (solid curve) and measured THz voltages (squares) of the DFG THz source versus the interaction length at 1.48 THz. The inset shows the absorption coefficient of our GaSe crystal measured with a THz time domain system.
Fig. 6. Dependences of THz voltages and average power on the 2 μm dual-wavelength pump power. The red line is a quadratic fit of experimental data points. The inset shows the THz signal detected by using the 4.2 K Si bolometer.
Fig. 7. THz intensity as a function of the rotation angle of the THz polarizer at 1.48 THz.
Fig. 8. Accepted PM angle of the GaSe crystal at 1.48 THz.
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