Enhanced Terahertz Wave Generation via Stokes Wave Recycling in Non-Synchronously Picosecond Pulse Pumped Terahertz Source

Abstract

Enhanced terahertz wave generation via Stokes wave recycling in a nonsynchronously picosecond pulse pump configuration has been demonstrated. It is theoretically analyzed that under the condition of high pump peak power density, the oscillation of the strong 1st order Stokes wave could benefit the higher order Stokes wave emission and terahertz wave generation. In the experiment, 5.71 times enhancement of terahertz wave generation was obtained via Stokes wave recycling in the non-synchronously picosecond pulse pumped terahertz parametric generator compared with the conventional single-pass terahertz parametric generation. The maximum terahertz wave average power was 61.7 μW under the pump power of 20 W and the cavity length of 170 mm, while the maximum power conversion efficiency was 3.085 × 10 −6 .

Continuously Tunable and Energy-Enhanced Injection Pulse-Seeded Terahertz Parametric Generator Based on KTP Crystal

“…In a cascading process, more than one THz photon is generated from the depletion of a single pump photon, so it will break the limit of quantum defect according to Manley-Rowe relations and improve the photon conversion efficiency. This phenomenon has been proved in other works. , With the increase of the pulse-seed laser wavelength, the first- and second-order Stokes waves also had a red shift according to the phase-matching conditions. It can be well illustrated by the four spectral curves in the middle of Figure a, where the pulse-seed laser wavelength changed from 1075.86 to 1077.06 nm.…”

“…This phenomenon has been proved in other works. 7,31 With the increase of the pulse-seed laser wavelength, the firstand second-order Stokes waves also had a red shift according to the phase-matching conditions. It can be well illustrated by the four spectral curves in the middle of Figure 5a, where the pulse-seed laser wavelength changed from 1075.86 to 1077.06 nm.…”

Phase-Matching in Nonlinear Crystal-Based Monochromatic Terahertz-Wave Generation

“…CW-TPO was achieved by putting a Si prism-coupled MgO:LiNbO 3 crystal within an end-pumped Nd:GdVO 4 laser resonator [93]. Later, sub-nanosecond (sub-ns) or picosecond (ps) lasers were employed as the pump source, combing a tunable seed and forming an is-TPG to pursue high peak power [94][95][96][97][98][99]. A real-time spectroscopic measurement system based on a multi-frequency is-TPG was set up by inputting five seed beams simultaneously [9].…”

Enhanced picosecond terahertz wave generation based on cascade effects in a terahertz parametric generator

“…As a picosecond (ps) pulse pumped terahertz source could suppress the SBS effect and increase the conversion efficiency by about three orders of magnitude, [12] ps pulse pumped terahertz sources have been developed recently. [13][14][15][16] To obtain high-repetition-rate THz operation, Aravindan et al [14] and Takida et al [15] used a bow-tie cavity to generate THz waves at 80 MHz repetition rate, where the maximum THz average power was 5.4 µW and dozens of nano-Watts, respectively. In 2019, our group used a non-synchronous picosecond pulse pump configuration to generate high-repetition-rate THz waves at 1 kHz, where the oscillation of the strong first-order Stokes wave in the TPO structure could benefit the higher-order Stokes wave emission and THz wave generation.…”