Dynamically Tunable, Narrowband Terahertz Emitters Designed by Tailoring Magnon-Phonon Interaction in Multilayer Heterostructures

A dynamically tunable, narrowband terahertz (THz) source is much needed for an accurate identification and imaging of chemical and biological species, with wide-ranging applications from security screening to medical imaging and to semiconductor inspection. However, existing pulsed THz sources are mostly single-cycle, broadband, and difficult to tune dynamically. In this presentation, the speaker will first introduce an approach that permits converting a femtosecond laser pulse into a multi-cycle, narrowband THz pulse via resonant magnon-phonon interaction. The peak frequency of the emitted THz pulse can be tuned by up to 50% through a varying bias magnetic field. The speaker will then present computational demonstration of this approach in several carefully designed ferromagnet and antiferromagnet based multilayer heterostructures, which allows us to cover without gaps different frequency ranges (deep millimeter-wave, sub-THz, and >1 THz) of the THz spectrum, tune the polarization, duration, and power of the emitted THz pulse. The demonstration was performed based on an in-house dynamical phase-field model that incorporates the coupled dynamics of magnons, phonons, photons, and plasmons in multiphase systems.