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Sunday, August 7, 2016
Abstract-Cascaded parametric amplification for highly efficient terahertz generation
Cascaded parametric amplification for highly efficient terahertz generation
Koustuban Ravi, Michael Hemmer, Giovanni Cirmi, Fabian Reichert, Damian N. Schimpf, Oliver D. Mücke, and Franz X. Kärtne
A highly efficient, practical approach to high-energy multi-cycle terahertz (THz) generation based on spectrally cascaded optical parametric amplification (THz-COPA) is introduced. Feasible designs are presented that enable the THz wave, initially generated by difference frequency generation between a narrowband optical pump and optical seed (0.1–10% of pump energy), to self-start a cascaded (or repeated) energy downconversion of pump photons in a single pass through a single crystal. In cryogenically cooled, periodically poled lithium niobate, unprecedented energy conversion efficiencies >8%achievable with existing pump laser technology are predicted using realistic simulations. The calculations account for cascading effects, absorption, dispersion, and laser-induced damage. Due to the simultaneous, couplednonlinear evolution of multiple phase-matched three-wave mixing processes, THz-COPA exhibits physics distinctly different from conventional three-wave mixing parametric amplifiers. This, in turn, governs optimal phase-matching conditions, evolution of optical spectra, and limitations of the nonlinear process. Circumventing these limitations is shown to yield conversion efficiencies ≫10%.