title: Energy scaling of terahertz-wave parametric sources.
abstract: 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/cm(2) 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.
authors.forename: Guanqi
authors.initials: G
authors.lastname: Tang
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Cong
authors.forename: Zengguang
authors.initials: Z
authors.lastname: Qin
authors.forename: Xingyu
authors.initials: X
authors.lastname: Zhang
authors.forename: Weitao
authors.initials: W
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Wu
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
authors.forename: Qingming
authors.initials: Q
authors.lastname: Lu
authors.forename: Shaojun
authors.initials: S
authors.lastname: Zhang