High-field multicolor THz waveform synthesis with dual PPLN emitters.

Reconfigurable high-field terahertz (THz) waveform synthesis could enable resonant, phase-sensitive control of low-energy excitations. The existing shaping approaches are often either hard-wired by the emitter structure or restricted to low field levels. Here, we demonstrate a modular platform for coherent THz waveform synthesis by combining two periodically-poled lithium niobate (PPLN) emitters with different poling periods. By adjusting the crystal relative polarity, the pump-pulse delay, duration, and energy, we control the field temporal shape and the multicolor spectral output. The synthesized waveforms are well reproduced by direct field addition in the time domain, confirming coherent field-level control. Importantly, this reconfigurability is achieved at µJ-level THz energies with peak fields of the order of 100 kV/cm, placing reconfigurable THz synthesis in the strong-field regime. We further compare parallel and series arrangements of the PPLN emitters, demonstrating coherent field combination and waveform extension in time, respectively. This two-emitter source establishes a simple route toward modular N-emitter PPLN arrays for tailorable high-energy THz waveform generation.