Terahertz waveform synthesis in integrated thin-film lithium niobate platform

• Published in: Nature communications 2023-01, Vol.14 (1), p.11-9, Article 11
• Main Authors: Herter, Alexa, Shams-Ansari, Amirhassan, Settembrini, Francesca Fabiana, Warner, Hana K., Faist, Jérôme, Lončar, Marko, Benea-Chelmus, Ileana-Cristina
• Format: Article
• Language: English
• Subjects: 639/624/1075/1079; 639/624/400/385; 639/624/400/561; 639/766/400/385; 639/766/400/561; Amplitudes; Broadband; Controllability; Crystals; Far fields; Femtosecond pulses; Humanities and Social Sciences; Lithium; Lithium niobates; multidisciplinary; Object recognition; Phase matching; Science; Science (multidisciplinary); Spectral emittance; Synthesis; Thin films; Waveforms
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-35517-6

Bridging the “terahertz gap“ relies upon synthesizing arbitrary waveforms in the terahertz domain enabling applications that require both narrow band sources for sensing and few-cycle drives for classical and quantum objects. However, realization of custom-tailored waveforms needed for these applications is currently hindered due to limited flexibility for optical rectification of femtosecond pulses in bulk crystals. Here, we experimentally demonstrate that thin-film lithium niobate circuits provide a versatile solution for such waveform synthesis by combining the merits of complex integrated architectures, low-loss distribution of pump pulses on-chip, and an efficient optical rectification. Our distributed pulse phase-matching scheme grants shaping the temporal, spectral, phase, amplitude, and farfield characteristics of the emitted terahertz field through designer on-chip components. This strictly circumvents prior limitations caused by the phase-delay mismatch in conventional systems and relaxes the requirement for cumbersome spectral pre-engineering of the pumping light. We propose a toolbox of basic blocks that produce broadband emission up to 680 GHz and far-field amplitudes of a few V m −1 with adaptable phase and coherence properties by using near-infrared pump pulse energies below 100 pJ. Miniaturized platforms are desirable for terahertz applications. Here the authors demonstrate chip-scale THz generation with controllable waveforms using thin-film lithium niobate.