Abstract-Energy scaling of terahertz-wave parametric sources

Energy scaling of terahertz-wave parametric sources Guanqi Tang, Zhenhua Cong, Zengguang Qin, Xingyu Zhang, Weitao Wang, Dong Wu, Ning Li, Qiang Fu, Qingming Lu, and Shaojun Zhang  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-4-4144

Optics Express, Vol. 23, Issue 4, pp. 4144-4152 (2015)
http://dx.doi.org/10.1364/OE.23.004144

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Terahertz-wave parametric oscillators (TPOs) have advantages of room temperature operation, wide tunable range, narrow line-width, good coherence. They have also disadvantage of small pulse energy. In this paper, several factors preventing TPOs from generating high-energy THz pulses and the corresponding solutions are analyzed. A scheme to generate high-energy THz pulses by using the combination of a TPO and a Stokes-pulse-injected terahertz-wave parametric generator (spi-TPG) is proposed and demonstrated. A TPO is used as a source to generate a seed pulse for the surface-emitted spi-TPG. The time delay between the pump and Stokes pulses is adjusted to guarantee they have good temporal overlap. The pump pulses have a large pulse energy and a large beam size. The Stokes beam is enlarged to make its size be larger than the pump beam size to have a large effective interaction volume. The experimental results show that the generated THz pulse energy from the spi-TPG is 1.8 times as large as that obtained from the TPO for the same pumping pulse energy density of 0.90 J/cm² and the same pumping beam size of 3.0 mm. When the pumping beam sizes are 5.0 and 7.0 mm, the enhancement times are 3.7 and 7.5, respectively. The spi-TPG here is similar to a difference frequency generator; it can also be used as a Stokes pulse amplifier.

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