Pulse Sequences for Efficient Multi-Cycle Terahertz Generation in Periodically Poled Lithium Niobate

Abstract

The use of laser pulse sequences to drive the cascaded difference frequency generation of high energy, high peak-power and multi-cycle terahertz pulses in cryogenically cooled periodically poled lithium niobate is proposed. Detailed simulations considering the coupled nonlinear interaction of terahertz and optical waves show that unprecedented optical-to-terahertz energy conversion efficiencies > 5%, peak electric fields of hundred(s) of Mega volts/meter at terahertz pulse durations of hundred(s) of picoseconds can be achieved. The proposed methods are shown to circumvent laser-induced damage at Joule-level pumping by 1$\mu$m lasers to enable multi-cycle terahertz sources with pulse energies >> 10 milli-joules. Various pulse sequence formats are proposed and analyzed. Numerical calculations for periodically poled structures accounting for cascaded difference frequency generation, self-phase-modulation, cascaded second harmonic generation and laser induced damage are introduced. Unprecedented studies of the physics governing terahertz generation in this high conversion efficiency regime, limitations and practical considerations are discussed. Varying the poling period along the crystal length and further reduction of absorption is shown to lead to even higher energy conversion efficiencies >>10%. An analytic formulation valid for arbitrary pulse formats and closed-form expressions for important cases are presented. Parameters optimizing conversion efficiency in the 0.1-1 THz range, the corresponding peak electric fields, crystal lengths and terahertz pulse properties are furnished.

arXiv comment24 pages, 11 figures

References in corpus (6)

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• Terahertz-driven linear electron acceleration
• Limitations to THz generation by optical rectification using tilted pulse fronts
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Cited by in corpus (8)

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• Raman Shifting induced by Cascaded Quadratic Nonlinearities for Terahertz Generation
• Full 3D+1 modelling of the tilted-pulse-front setups for single-cycle terahertz generation
• Generating compressed broadband terahertz pulses using aperiodically poled electro-optic crystals
• Terahertz-induced cascaded interactions between spectra offset by large frequencies
• Simulations on a potential hybrid and compact attosecond X-ray source based on RF and THz technologies